This report provides a comprehensive overview of enforcement actions, compliance issues, and regulatory developments in the drinking water industry during Q3 and Q4 of 2024, with a forward look into AMP8 obligations.
The Inspectorate issued a range of legal instruments to address potential risks to drinking water quality and security. In total, 26 regulation 28(4) notices were served to mitigate potential risks identified in water safety plans, alongside five final enforcement orders under section 18 of the Water Industry Act 1991 (the Act), and five undertakings under section 19(1) of the Act. Notably, Southern Water now holds seven live final enforcement orders which is a first for any water company and reflecting its systemic delivery challenges. Thames Water also received two final enforcement orders for failing to formalise supported schemes under the Security and Emergency Measures Direction 2022. Additional notices targeted issues such as elevated lead levels, iron failures, Cryptosporidium risks, and structural integrity concerns at service reservoirs, with completion dates extending into AMP9 for some schemes.
Late PR24 submissions were accepted by exception, resulting in new regulation 28(4) notices for emerging risks. AMP8 priorities include PFAS mitigation strategies across multiple companies, nitrate risk management, and catchment-based approaches. For example, Anglian Water and United Utilities will install granular activated carbon treatment to address emerging PFAS contamination, while Wessex Water is implementing a hydrogeological modelling program to inform PFAS catchment management. Completion timelines for these schemes range from 2030 to 2036, reflecting the complexity and scale of interventions.
AMP8 introduces stringent targets: a maximum of 0.94 contacts per 1,000 population per water quality zone and an industry average of 0.3 by 2030. Outlier companies such as Dŵr Cymru Welsh Water and South West Water have been assigned stretching targets, while Wessex Water has aligned with industry expectations. These measures aim to drive sustained improvements and reduce variability between water company areas.
In collaboration with Ofwat, the Inspectorate formalised “Acknowledged Actions” for schemes outside its regulatory remit but deemed beneficial for public health. These include catchment investigations, disinfection resilience upgrades, and emerging contaminant studies. While not legally binding, these actions are monitored closely and may escalate to formalised delivery in response to findings or if risks change.
Technical audits revealed recurring deficiencies in filter performance, maintenance, and risk assessment practices across multiple companies. Specific issues included inadequate Powder Activated Carbon (PAC) dosing, delayed refurbishment of critical assets, and poor sampling arrangements. Enforcement was initiated where necessary to secure compliance with regulation 4. Events such as the ‘Lightshaw source change’ and ‘Oughtershaw service reservoir contamination’ highlighted gaps in risk assessment, consumer communication, and operational response, underscoring the need for timely investigations and robust asset management.
Key updates include the publication of PFAS guidance, mandating risk reduction strategies and enhanced monitoring requirements by January 2025. The Inspectorate also advanced work on Drinking Water Safety Plan guidance, emphasizing World Health Organization (WHO)-aligned approaches and improved reporting consistency under regulation 28.
Compliance, events and audits
Treatment works
Lartington works
Northumbrian Water had a turbidity breach at Lartington works in July. A regulatory sample taken from the works’ final sample point returned a turbidity of 1.1 NTU. The company attributed the turbidity result to deposits in the regulatory sample line which may have been dislodged at the time of sampling, as the sample tap upstand was found to be loose during the investigation into the detection. This was later rectified, and the sample tap upstand was fixed to a concrete pillar. The sample line from the outlet main was also rerouted. A turbidity exceedance of 1.3 NTU was previously reported in January 2024, which the company also attributed to sediment in the sample line. The sample line connection to the outlet main was replaced following the January exceedance. The Inspectorate gave two recommendations around the company’s auditing process which did not identify all the deficiencies with the sample point and to revisit the conclusions from the other audits, that the company had carried out at other treatment works, to ensure they were carried out appropriately. A suggestion was also given to review the weekly sample line flushing frequency.
Oswestry works
United Utilities had a coliform breach of 38 per100 ml in a sample from Oswestry works in August. On the days preceding the breach, significant valving operations were undertaken at Oswestry works to allow the installation of outlet pipework on the new second stage Rapid Gravity Filters (RGFs). In addition to valving, the work also necessitated diverting the entire works’ flow via stream 1, which involved closing the outlets on the stream 2 slow sand filters (SSF) and bringing them back online via stream 1. A defect was later identified with slow sand filter 12. The filter was removed from supply and an investigation revealed that a tile on the filter floor had moved out of place. This was subsequently rectified and returned to supply.
The company concluded that this could not be ruled out as the cause of the coliform detection. Further trends were provided in the exception report to demonstrate that the water had been adequately disinfected prior to and on the day of the exceedance. While the company were able demonstrate Ct was satisfactory on the day of the infringement, trends from the stream 1 UV reactors showed outages on the system. Follow-up information from the company confirmed that between May and October 2024 there were UV outages on 22 occasions at Oswestry works and Oswestry (at Hindford) works. It was concluded that the company had not complied with the requirements in the notice UUT-2022-00003 Oswestry, to complete the installation and commissioning of validated UV disinfection treatment capable of treating full works flow (180 ML/d) and to optimise existing treatment processes to ensure continuous compliance with regulation 26. An ‘intention to vary notice’ was served to the company.
The company have acknowledged the new requirement to report any outages of the UV system to the Inspectorate and are continuing to identify additional control measures that can be introduced to reduce the number or duration of outages of the system as well as reviewing the feasibility of installing auto changeover on UV1 and UV2 at Oswestry works (Hindford).
Whilst the company conducted a thorough investigation, it was unable to prove a root cause. The SSF defect may have been the cause, and thus highlighting the importance of multibarrier treatment. Whilst Ct was met, the UV barrier was demonstrated to be unreliable and therefore may not have provided its intended mitigation when it was needed.
Service Reservoirs
South East Water detected a single coliform in a sample collected from Chillies service reservoir number one in August. The service reservoir had recently been returned to service, having been removed from supply in September 2022 for internal remediation work and for work on local distribution pumps. During the investigation of this breach, it was established that the company did not sample the reservoir immediately before its return to service, instead a sample was collected two weeks prior however, in the meantime, the service reservoir had been drained and refilled. The Inspectorate recommended that the company collects service reservoir pre-commissioning samples from the actual volume of water that is going to be valved into supply, to confirm wholesomeness and that the company ensure lessons learnt from this breach were briefed to relevant teams.
Anglian Water detected coliforms in a sample collected from Etton service reservoir in July. Whilst the route cause was identified to be from ingress that was found on all nine technocover hatches, which was later rectified prior to returning the asset to supply, additional deficiencies were identified, as well as issues with other assets on the connected supply system. It was noted that the borehole CCTV surveys for the Etton and Northborough boreholes should have been conducted every AMP period and were overdue, with the previous inspections having been conducted between 1997 and 2008 for the four boreholes. It was also noted that there was no sampling tap on the incoming supply from Wing works, which made up approximately 50% of the supply at Etton service reservoir.
Recommendations were given for the company to prioritise CCTV surveys on the boreholes and as well as to install a sampling tap on the incoming treated water supply from Wing works, in order that future investigations can include appropriate sampling to rule out the quality of water from each incoming supply.
Zones
Following a taste and odour detection in Wessex Water’s Fovant zone in July, the company completed an investigation into the failure which included resampling from the original property and nearby properties. All follow up samples were clear and a review of consumer contacts from the area did not identify an increase in contact numbers. A water fittings inspection at the original property identified that there were rubber flexible hoses supplying the kitchen mixer tap and that the body of the tap remained warm. The company advised the consumer to replace both the tap and the flexible hoses.
The company investigation identified intermittent slight musty tastes from the upstream Fir Hill number 1 and 2 service reservoirs, so the Inspectorate recommended the company fully investigates these detections to ensure that there is not a wider issue with the water quality being supplied from these sites. The company had previously identified a risk with taste and odour due to inadequate turnover from these service reservoirs with the risk being under investigation in its regulatory risk assessments.
In August, Wessex Water had a breach of the taste parameter with the descriptor of ‘musty’ in a sample collected from a consumer property in the Danesborough zone. In the month prior to the breach, the company received above average numbers of taste and odour contacts from consumers in this water supply zone and had initiated an investigation. The company eventually identified the compound 2,4,6-trichloroanisole (TCA), which can cause a musty taste / odour, in post-contact tank samples taken from Durleigh works. The works was taken out of service in September and the Flexcrete Cementitious coating 851 lining in the contact tank, which had been applied in 2020, was found to be thin, eroding and peeling above the water line.
The company had previously experienced a similar issue at its Alton Pancras works in 2022, where the same coating had been used in the balance tank and TCA had subsequently formed. At Alton Pancras, the company removed the failed lining and applied a different liner. The company conducted a review identified that the product had also been used at a different site and initiated a sampling survey. Wessex Water is carrying out ongoing discussions with the manufacturer of the coating, the contractor and industry experts to establish the reason for the liner breaking down.
In September, United Utilities had a coliform failure in the Chorley zone. It was concluded that the company had conducted a satisfactory investigation, however, were unable to determine the cause of the exceedance. However, upon reviewing the trends that were provided by the company for the upstream works, an issue with the contact tank outlet and final chlorine monitors was noted from Hodder works where the company could not verify the effectiveness of disinfection. Two recommendations were given for the company to review guidance and training associated with its standard operating procedure and to review processes and training to ensure that the start-up to waste checklists are used and followed during a site start up.
Events
Lightshaw customer contacts
This event involved a planned change to the source water supplied to United Utilities consumers in areas of St Helens and Wigan in July 2023. Lightshaw works is located in Golborne, near Warrington. It treats ground water and is routinely brought into and out of service to balance supply and demand across the company’s supply system. When Lightshaw works is out of supply, the downstream water supply zones (WSZs) are supplied via water from the Rivington large diameter trunk main, a relatively softer water source. Lightshaw works supplies district metered areas (DMAs) within WSZs 120 (Lightshaw), 121 (Ashton) and 125 (Haydock).
Lightshaw works was returned to supply on 21 July 2023. One DMA that received a supply from Lightshaw works during this period was DMA 120-25, a relatively new DMA that was created between 2022 and 2023. DMA 120-25 was previously within WSZ 118 and had not recently received a harder water supply from Lightshaw works.
Between the 24 July and 6 September 2023, the company received 120 consumer contacts from WSZs 120 and 125, 49 of which were from DMA 120-25, expressing concern for water quality. The company also received a total of 366 written complaint letters from consumers also located in DMA 120-25. One consumer from DMA 120-25 contacted the Inspectorate to complain their water supply was discoloured and had made them ill. Due to complaints regarding water quality from consumers in DMA 120-25, the company rezoned the network in September 2023 to supply DMA 120-25 from WSZ 118 via the Manchester Ring Main.
Although the company carried out a risk assessment before returning Lightshaw works to supply, the risk assessment failed to adequately consider the effect of source water change on consumers, especially those who had not previously received a supply from Lightshaw works. The company did send proactive communications to consumers to inform them of a planned change to the water supply, however, the information provided failed to offer reassurance, and furthermore, several consumers did not receive any proactive communication from the company. The Inspectorate considers that the company failed to fully implement learning from the Copeland area event in 2017.
Sampling data provided by the company demonstrated that the water supplied to consumers during the event complied with the standards specified in schedule 1 of the Water Supply (Water Quality) Regulations 2016 (as amended). However, the Inspectorate concludes the company supplied unwholesome water when consumers were provided with water from Lightshaw works because it imparted a noticeable change to the appearance, taste and odour of the water supply, which consumers did not find acceptable. This is also evidence from the consumer questionnaires and statements that consumers rejected the water for drinking, cooking, and washing.
The company was issued a warning letter on 4 July 2024. The event highlights the importance of comprehensive risk assessments and effective consumer communication when altering source water supplies. Companies are reminded of their duty under section 68(1)(b) of the Water Industry Act 1991 where, so far as reasonably practical, there is no deterioration in the quality of the water which is supplied from time to time from a source or combination of sources. This also underscores the need for better anticipation of consumer acceptability issues, targeted communications, and more robust implementation of lessons learned from past incidents.
Following the event, the company commissioned independent research to review the contact data in the hotspot areas, previous communications and identify control locations for the research to understand the drivers for consumer contacts and to test behavioural science levers to determine effectiveness. As a result, the company communications were amended based on customer feedback and focus groups were reconvened to capture feedback following the redesign. The company found that the communication needed to set expectations effectively, neurodiversity and those with medical conditions should be considered and the revised communication provided more reassurance and covered customers key questions.
Yorkshire Water Oughtershaw service reservoir
A compliance sample taken from Oughtershaw service reservoir 24 September 2024 was found to contain 122 coliforms per 100 ml. On 25 September 2024, a restriction of use boil water advice was provided to one property downstream of the asset in the K848 Oughtershaw DMA and on 26 September 2024 boil water advice was provided to the remaining eight properties. An operational sample taken 26 September 2024 from Oughtershaw reservoir outlet, contain E. coli >1000 per 100ml.
A compliance sample from Oughtershaw service reservoir taken on 30 September 2024 contained 48 coliforms and 23 E. coli per 100ml. Compliance samples collected between October and November breached the standard for coliforms a further four times (see table 1 below).
Oughtershaw service reservoir
Number of Coliforms / 100 ml
16/10/2024
74
24/10/2024
3
01/11/2024
8
20/11/2024
43
Table 1 Oughtershaw sample results
Oughtershaw service reservoir was not fully bypassed and taken out of service until 4 March 2025. Microbiological water quality improved significantly thereafter, and the health protection advice was lifted at all properties on 13 March 2025. Restriction of use advice remained in place for consumers for 201 days.
The company carried out Cryptosporidium tests of 46 samples in total with no oocysts detected during the event. The Inspectorate noted a significant delay in the company’s investigation to the breach in September and the failure of the company to carry out a walk over of the main until 9 December 2024 where an unmapped air valve was discovered. In addition, there were still unanswered questions regarding potential cross connections with the old, decommissioned works onsite. A recommendation was given for the company to review its procedures to ensure that investigations are carried out in a timely manner to mitigate against further breaches.
The company state it is also in the process of creating a new continuous improvement team within the Water Quality department that will run root cause analysis reviews for all water quality events in future to prevent a recurrence.
The key learnings from this water quality event are critical and wide-ranging, particularly for improving operational response. Timely, thorough investigations and up-to-date asset records are essential for effective incident management.
Audits
Throughout the second half of the year, the Inspectorate carried out technical audits across the industry to evaluate works’ performance.
In October, the Inspectorate visited Southern Water’s Brede works and made several recommendations. Brede works is a surface water site treating water from Powdermill and Darwell surface water reservoirs and four interconnected wells. These were for the company to investigate and implement methods to ensure coagulant dose and DAF performance is optimised; to rectify the shortfall in media replacement which had not been corrected for six years; to investigate the settlement time following filter backwash which was recorded by the company to be 10 minutes long; to investigate the cause of the recurrent Clostridium perfringens detections and to develop robust short and long-term solutions to reduce the risk of further detections. Further recommendations were made against filter performance, operation, inspections, primary filter roof repair and planned maintenance to clean the filter lauders. In the long term, the Inspectorate recommended replacement of the filters with a more appropriate and robust solution.
The Inspectorate found the works’ final water turbidity alarm allowed water to enter the final stage of disinfection for 30 seconds at a turbidity greater than 1 NTU before allowing the works to shut down. A recommendation was made to the company to introduce an appropriate alarm to allow works shutdown before the requirements of regulation 26 are breached at this site. The Inspectorate reminds all companies that water with a turbidity of greater than 1 NTU entering the final point of disinfection is in breach of the Regulations and all precautions must be taken to prevent this scenario. Brede works is currently subject to an improvement notice, however the Inspectorate was minded to initiate further enforcement action following the audit.
In October, the Inspectorate also visited South East Water’s Green works. The works is a surface water Hazards Green works in East Sussex. Water is abstracted from the Wallers Haven River, Darwell Reservoir (which is managed by Southern Water) and an onsite well. South East Water list ‘media depth checks’ for filters as a control measure on the company regulatory risk assessment however at Hazards Green it was apparent these checks were not taking place. The Inspectorate recommended the company review all sites to ensure that media depth checks are being completed at the required frequency and that the company update its Drinking Water Safety Plans to reflect the work it has identified to improve the control monitoring systems at the site.
In November, the Inspectorate carried out an audit at Anglian Water’s Pitsford works, which is a large surface water site located in Northampton, supplied by the River Nene, Pitsford Reservoir and Holcot, Walgrave and Scaldwell Brooks. The most significant challenge at the works is from pesticides, for which there is Granular Activated Carbon (GAC) treatment in place.
During the audit, Rapid Gravity Filter (RGF) 1 and 8, were found to be drained down and out of service for filter nozzle replacement. A subsequent data request following the audit found that RGF1 had been out of supply since April 2021 and RGF8 since May 2022 as the company had not been able to procure approved nozzles. The Inspectorate was critical that the status of the remaining six filters was being impacted by the company’s passivity in addressing the refurbishment issue and it was recommended that the company remediate the filter issues on site as a priority, so that the requirements of regulation 4 are not impacted in future.
A further recommendation was made to review how the company’s maintenance systems highlighted instrument calibration dates in response to a turbidity instrument not receiving a timely two-year full loop calibration over a four year period between 2020 and 2024.
The Inspectorate also audited Affinity Water’s Kingsdown works and found the company has not reported any compliance data for the pesticides aldrin, dieldrin, heptachlor and heptachlor epoxide in recent years. A recommendation was provided for the company to ensure compliance with regulation 6 in regard to the four aforementioned pesticides at this works and across the company’s estate. Another recommendation was made to ensure samples from Kingsdown works are always representative of water leaving the works as required by regulation 16, since the final water sampling tap had the possibility of being supplied by the network rather than the works, if the works is not pumping in to supply.
Many further recommendations were made including to consider sewer pumping stations within the catchment risk assessment; to review the regulation 27 records for risks associated with generators and transformers to be considered and updates to the regulation 28 report made; to ensure risks associated with chlorate are controlled; and to hygienically seal an observation borehole located in close proximity to the site operational borehole.
The Inspectorate’s risk-based audit programme at works has found many recurrent themes across the industry, particularly with regards to inadequate filter performance and maintenance, site-wide risk assessments and general site maintenance. Optimal filter performance and filtration are critical components of the production of a safe and high-quality water into supply. However, at the majority of the sites audited, filter performance was found to be sub-optimal, with deficiencies observed in routine maintenance, inspection, cleaning and timely remedial interventions. Continuous risk assessment of treatment works should inform timely updates to regulation 27 risk assessments and 28 reports with appropriate short-, medium- and long-term mitigation and control measures in place. However, this was also found to be inadequate at some of the works that had been audited. Site maintenance was also overlooked at almost all the works audited, in some cases for years, leaving assets to deteriorate. The Inspectorate will always recommend or initiate enforcement to ensure compliance against regulation 4 in order to maintain wholesome water supplies to the public.
Wales
Compliance
HDC – Penrhos
In July 2024, Hafren Dyfrdwy reported a coliform failure in a sample taken at Penrhos service reservoir. The asset was taken out of supply and ingress was observed through the hatch seals during a flood test as the sealant had deteriorated, the company therefore attributed the failure to this ingress point. An external inspection conducted in August 2024 noted an additional potential contamination route due to an absent flap valve on the environmental discharge point. This had not been noted during the external inspection, which was conducted immediately following the failure, therefore an earlier opportunity to identify a route of contamination into the asset was missed. The company subsequently replaced the hatch seals and fitted appropriate backflow protection on the discharge pipe.
HDC – Bongoch
Taste and odour failures (“musty”) occurred in the Bontgoch water quality zone in April and July 2024. This is a continuation of a pattern of such failures since 2020 and a definitive root cause has not been identified. Contributing factors featuring in investigations include property fittings infringements, low turn-over of the local network, elevations in local chlorine residuals and the occurrence of low concentrations of 2,3,4-trichloroanisole in sample results. The company have employed an independent body to investigate the root cause(s) of these breaches, and the results of this investigation are due in July 2025.
DWR – Plas Talgarth
Dŵr Cymru Welsh Water reported a coliform failure associated with a routine sample taken at Plas Talgarth service reservoir in September 2024. The subsequent company investigation included an internal inspection. During this inspection, a flood test was conducted which identified ingress into the asset through the single-skinned glass reinforced plastic (GRP) hatches. These were not compliant with the company security specification for hatches; bespoke replacement covers were subsequently installed at this site in January 2025.
The single-skinned GRP hatches were noted in the most recent external inspection of the service reservoir conducted prior to the coliform detection. However, they were not raised for replacement or remediation at that time. Instead, at the time of the failure, the relevant risk assessment line was assigned a DWI category of A ‘Target risk mitigation achieved, verified and maintained’ with ‘Technocovers’ listed as a control measure, even though they were not in place at this site.
The company proactively conducted a review into the presence of non-standard hatches at their service reservoirs; 15 sites were identified with non-standard hatches. The company has concluded that capital investment is required at all sites to rectify the identified security issues and work is ongoing. The Inspectorate recommended that the company review the risk assessment categorisation for the relevant risk assessment lines at sites with non-standard hatches and puts in place appropriate mitigation actions.
Events
DWR – Grosmont
In July 2024, a contractor reported to Dŵr Cymru Welsh Water an oily residue in the communications pipe excavation between two consumer properties. The company visited the area on the same day and sampled a single downstream property. The following day one of the properties beside the excavation was sampled, an odour was detected on the pre-flush sample, however no restriction of use was issued. Two days later the company returned to take additional investigatory samples. Six days after the initial report of hydrocarbon contamination, ‘do not drink’ advice was issued to the two properties adjacent to the contaminated excavation.
Following the event the company made changes to their customer contacts procedure to ensure that delays in taking appropriate samples would not result in a delay to the issuance of precautionary restriction of use advice. The procedure was updated to include boundary box sampling where access to the consumer property was not immediately possible, and to consider the presence of on-site hydrocarbon soil contamination as a trigger for issuing restriction of use. Companies are encouraged to widely consider information and data inputs into dynamic risk assessments, particularly when feeding into decisions regarding precautionary restrictions of use.
DWR – Neath – shared supply lead.
Dŵr Cymru Welsh Water reported an event in July 2024 following the failure of a lead sample taken at a consumer property. A subsequent sampling survey did not highlight any elevated concentrations of lead in neighbouring properties. The company found that its communications pipe was polyethylene, however, the consumer’s supply pipe was found to be lead. The company responded promptly, replacing the supply pipe and resampling at the property to confirm that lead concentrations were below the limit of detection as a result. The Inspectorate issued a recommendation regarding the issuance of restriction of use advice in the case of properties on a shared supply pipe. A ‘do not drink’ notice was issued to the original property following the initial lead failure, however, a second property on the shared lead supply was not issued with a restriction of use at the same time. The sample taken at this property showed lead less than the limit of detection at the time of sampling. The company has since updated its lead response procedure to require ‘do not drink’ advice to be extended to all properties that share a supply pipe, where such advice has been issued to one of the properties.
HDC – Newtown do not drink
In July 2024 Hafren Dyfrdwy reported a suspected ingress event to the Inspectorate. The company was alerted to a burst on a three-inch main in the Newtown zone. Whilst the company were repairing the initial burst a secondary burst occurred which drained a tanker which was infusing into the network, the subsequent depressurization allowed ingress into the main. A single property on the affected section was issued with ‘do not drink’ advice and the company elected to install a temporary overland main to maintain a “sanitary supply” to this property. The company acted quickly to repair, disinfect, and flush the main. The ‘do not drink’ advice to the single property was lifted following two sets of satisfactory sample results. However, the company did not follow its own procedure, as taste analysis was not included in these sampling suites. Whilst the company does not carry out taste analysis following the issuing of ‘do not drink’ advice, once the remedial works are complete and chemical analysis suggests it is safe to do so, taste analysis should be completed on the appropriate samples before a restriction of use notice is rescinded.
HDC – Newtown T&O
In September 2024 a consumer from a community centre in Llanidloes contacted Hafren Dyfrdwy to report a chemical/chlorine odour. After some delay and following confirmation of “solvent” and “river” odours by the laboratory taste and odour panel, do not drink advice was issued to the consumer and the heating system cross contamination source was identified during a reactive fittings inspection. There were initial delays in reactive sampling associated with deficiencies in contact classification and escalation processes during the investigation. An opportunity to issue the do not drink advice at an earlier juncture when a quality technician (sampler) also detected a chemical odour at the time of sampling was also missed. Companies are reminded of the importance of clear, unambiguous classification of water quality descriptors during initial contacts and of opportunities to protect consumers when sufficient evidence presents itself prior to the receipt of reactive sample results.
Audits
HDC – tanks and reservoirs
In August 2024, the Inspectorate audited four of Hafren Dyfrdwy’s service reservoir sites in the Wrexham area.
Secondary chlorination using sodium hypochlorite is in use at two of the sites, Sugn Y Pwll and Bronwylfa. At both sites, the sodium hypochlorite is stored in a single bulk tank which is replenished using stock from other company sites, with new product added onto existing. However, there was no provision or procedure for draining and cleaning the bulk tanks. The dosing equipment and bulk tanks are situated in outbuildings at each site, there was no temperature monitoring of these buildings or the product itself, and there was no robust method of temperature control or cooling. Sodium hypochlorite solution gradually decomposes over time and this decomposition is greatly affected by heat, a by-product of this decomposition is sodium chlorate. The Inspectorate made a recommendation for the company to revise the sodium hypochlorite management at the two sites audited to meet the requirements of the relevant standard (BS EN 901:2013), with particular reference to the risk of chlorate formation. Chlorate monitoring was scheduled to take place four times per year, which meant that only a single sample was likely to be taken during the summer and was therefore unlikely to capture any spikes in chlorate concentration. In response, the company increased the chlorate monitoring at service reservoirs with secondary chlorination to eight samples per year from January 2025.
The sampling facilities at each site were inspected during the audit. At two of the sites, Gronwen and Higher Berse, the tapping points for the regulatory sampling points are located on the inlet/outlet main which is used for both filling and discharging the respective reservoirs, it is therefore not possible to ascertain whether samples representative of the reservoirs are being taken at any given time. A recommendation was made to review the sampling arrangements at all company ebb/flow reservoirs to ensure that representative regulatory samples could be taken; the company review is ongoing.
At Gronwen service reservoir, a further recommendation was made regarding the sampling facilities, which were found to be in poor condition with inadequate drainage and a redundant line in the cabinet. Critical facilities such as this should not be found in poor condition and not meeting company asset standards. The Inspectorate understands that programmes to deliver improvements to small but common infrastructure will be spread over time and prioritised according to risk, however deficiencies such as these found at Gronwen service reservoir, should have been resolved in response to historic inspections.
Enforcement
The Inspectorate publishes the drinking water quality Legal Instruments on the website under company improvement programmes. Security (SEMD and NIS) legal instruments are considered sensitive and therefore are not published in the public domain. A summary of the Legal Instruments issued in this quarter is below.
Type of legal instrument
Number
Companies
Regulation 28(4) Notice relating to risks identified in water safety plans
14
Northumbrian Water (3) Severn Trent (3) South West Water (3) Thames Water (2) United Utilities (2) Wessex Water (1)
Enforcement Order under section 18 of the Water Industry Act 1991.
4
Severn Trent Water (1) Southern Water (1) Thames Water (2)
Regulation 15 Notice for information under the Network and Information Systems Regulations 2018.
1
Affinity Water
Table 2: Routine Enforcement Legal instruments issued in Q3 2024
The Inspectorate served a notice under regulation 28(4) on Southern Water for their Yew Hill Service Reservoir on 15 August 2022. It required that specified measures be carried out in order to prevent the deterioration in the quality of drinking water supplied. The company submitted a change application in early 2024, requesting date changes (delays). The Inspectorate concluded that the delays were as a result of inadequate management of the project and therefore should have been within the company’s control. Given the company’s track record in delivery delays and the ongoing public health risk presented by this reservoir, the Inspectorate proceeded to consult on and then make an enforcement order under section 18 of the Act. The population potentially impacted by this reservoir is 116,588 and the company must seek all opportunities to expedite this work to safeguard wholesome supplies of drinking water to them.
Southern Water now have seven live final enforcement orders, an unprecedented situation in the time that the Inspectorate has existed. The company must take steps to ensure that it delivers on all of its legal instrument commitments, in order to halt the progression through the enforcement escalation process we have seen over recent years that has resulted in these enforcement orders.
Thames Water submitted two PR24 schemes for the Inspectorate to consider for support, for improvements in meeting the requirements of the Security and Emergency Measures Direction (the Direction). The requested support was subsequently given. However, the company failed to submit section 19 undertakings to formalise the supported schemes. Audits undertaken by the Inspectorate confirmed the need for the improvements to be delivered in order to comply with the Direction and the company were given a further opportunity to offer undertakings. The company declined to do so, therefore the Inspectorate initiated enforcement under section 18 in the form of two final enforcement orders. These Orders have now been made and require the company to implement the required improvements.
In late September, Inspectors attended a former reservoir site, now used as storage for emergency, alternative supplies (pallets of bottled water). The bottles were found to be stored in wholly inadequate conditions, open to wildlife and vermin, and with detritus covering many of them. In order to protect public health, the Inspectorate immediately served a provisional enforcement order under section 18 of the Act. The order prohibited the use of this water for consumption by the public. It also required a thorough investigation into the circumstances of the storage conditions arising, the destruction of all bottled water stored at the site, an internal audit of storage conditions at all other company bottled water stores, including addressing any issues observed and a review of relevant procedures and training. The dates given in the Order require the work to be completed before the end of the calendar year.
A regulation 28(4) notice was served on Thames Water, at the company’s request, for Bowsey Service Reservoir. This reservoir was previously included within the wider Tank Inspection and Cleaning notice, however the company identified that this reservoir required further enabling work, so requested that it was put into its own discrete improvement programme. The Inspectorate agreed with this approach, and as such a new notice was served to address bacteriological risks associated with contamination from ingress into the reservoir. The scheme has a completion date of 31 December 2032 and will benefit a population of 36,927.
Following a serious event in September 2023, involving the detection of Cryptosporidium oocysts at Thames Water’s Sheeplands water treatment works, the Inspectorate concluded that the likelihood of recurrence was high and therefore enforcement action was initiated. A regulation 28(4) notice was served on Thames Water, requiring the company to take steps to address unmitigated water quality risks relating to Cryptosporidium and turbidity. The notice has a completion date of 31 August 2027, and will benefit a population of 36,927 people.
Beginning in March 2023, there was a serious water quality event in Wallasey, Merseyside, an area supplied by United Utilities. A cross-connection of a potable main with a non-potable main led to consumers being supplied with green, discoloured water. The Inspectorate was critical of United Utilities’ approach to network investigations and the use of water fittings inspections to aid its investigations. The company already had a regulation 28(4) notice in place, which contained measures to address deficiencies in water fittings and investigations, however these measures had already been completed. The Inspectorate did not consider that the company were in breach of this notice but considered that learning from the Wallasey event could be used to enhance the outcomes of the existing notice, strengthen the company’s procedures and carry out further training of its staff. The Inspectorate therefore decided to vary this notice under regulation 28(6), and reopen some of the steps, with the addition of other measures, to ensure the company took steps to incorporate learning into its management systems and prevent a recurrence. This notice will now be completed on 30 June 2025.
A notice under regulation 28(4) was served upon United Utilities, at the request of the company, for Winwick service reservoir. This reservoir was included in a wider improvement scheme for treated water storage tank cleaning and inspection; however, this wider notice was largely complete (see below), with Winwick Service Reservoir the only reservoir outstanding, and with some further work required. The Inspectorate agreed that this reservoir could be placed into its own improvement scheme, to address bacteriological risks associated with the integrity of the reservoir structure. This notice will be completed on 31 January 2026 and will benefit a population of 65,733.
In December 2023, Wessex Water reported a compliance breach of the total coliform parameter, at Chitterne works. The company was unable to determine a root cause for the exceedance, and there is only marginal chlorination at the works. Due to the known catchment risks, the observed raw water quality and the site currently using marginal disinfection with an undefined chlorine contact time, the Inspectorate concluded that there was a risk of further microbiological detections at this treatment works. Enforcement action was therefore initiated, and the Inspectorate served a notice under regulation 28(4) to ensure the company upgrades the disinfection to an appropriately designed and verified system. The notice is due to be completed on 30 April 2029, to the benefit of 878,894 people served by the treatment works.
Three notices under regulation 28(4) were served upon Northumbrian Water, following discussion with the company, for Whittle Dene Service Reservoir, Gunnerton contact tank and Horsley contact tank. They were originally included in a companywide notice for tanks and service reservoirs which is largely complete, however, these three projects, which require substantial engineering solutions would still be outstanding, with construction work yet to start. The Inspectorate agreed that the three schemes should be given their own notices to address disinfection risks and consistent with our tanks strategy and actions taken with other companies in similar scenarios. The completion date for Gunnerton is to be confirmed to the Inspectorate by 28 February 2025 to the benefit of 30,634 people served by the treatment works. Whittle Dene will be completed by 31 July 2028 to the benefit of 650,295 people served by the treatment works. Horsley will be completed by 30 June 2028 to the benefit of 847,536 people served by the treatment works.
Two events occurred at Frankley WTW which led to elevated iron entering into supply. The cause was due to components of the coagulation/clarification process not operating as expected. The Inspectorate is unable to conclude that further events will not occur. Therefore, a notice under regulation 28(4) was served on Severn Trent Water, to improve the operation of the treatment process, to the benefit of 2,079,618 consumers by June 2028.
Two notices under regulation 28(4) were served on Severn Trent Water for Trimpley and Melbourne water treatment works, to address the treatment of Cryptosporidium. Treatment and sampling processes are to be reviewed by 30 November 2025 to the benefit of 475,699 consumers in the Trimpley supply area and 1,614,139 in the Melbourne supply area.
Three notices under regulation 28(4) were served on South West Water following the annual return and submission of a change application for the existing “Review and revise water quality monitoring, control and investigations” company-wide notice. The aim of the existing notice is to improve onsite and portable monitoring, enhancing scientific investigation and will conclude in May 2025. Separate notices for Dousland, Prewley and Lowermoor Water Treatment Works were required, as access into the assets affected to carry out the required remediation could not be facilitated until enabling works are completed within the next investment period.
The Inspectorate’s NIS team conducted an audit of Affinity Water’s Cyber Assessment Framework. Despite advanced notice of the audit, the company were unprepared and were unable to produce the majority of the information requested. Therefore, a notice under regulation 15 of the Network and Information Systems Regulations 2018 was served on the company. This notice formally requires the company to provide all information required by the Inspectorate and which would ordinarily have been collected during the audit.
AMP8 Legal Instruments
Some companies submitted late PR24 submissions to the Inspectorate for consideration of support, immediately prior to Ofwat publishing its draft determinations on 11 July 2024. Whilst the Inspectorate’s deadlines were clear (for submissions to be completed during 2023), a small number of schemes were allowed to be submitted, by exception, where new risks to drinking water quality were emerging. The late submitted schemes that were supported, were formalised into regulation 28(4) notices during the third quarter.
Company
Scheme
Details
Affinity Water
AMP8 PFAS Strategy
AFW-2023-00013 the company submitted a section 19. Undertaking in line with industry to mitigate risks associated with PFAS.
Anglian Water
Barrow PFAS
The company were observing consistent Tier 2 PFAS levels in the final water from Warren Hill Reservoir, which is linked to PFAS in Southfields borehole 3. Borehole 4 is at Tier 1, but the company would like to mitigate due to its proximity to borehole 3 and the anticipated risk posed. The preferred solution is the installation of Granular Activated Carbon (GAC) on the two at risk borehole sources. The scheme will conclude in April 2031 and will benefit 44,881 customers.
Southfields PFAS
The company observed consistent tier 2 detections in raw and final water at Barrow water treatment works, with one tier 3 detection at a borehole in May 2024. Blending is not a sustainable option and treatment for PFAS is not in place. The company propose GAC as its preferred solution. The scheme will conclude in April 2031 and will benefit 108,225 customers.
South East Water
Cookham Nitrate
The company predict that nitrate will risk breaching PCV before the end of the next investment period. It will design and install a solution for addressing the nitrate risks at Cookham water treatment works. This scheme will be completed by 30 June 2030 and will benefit 142,667 consumers.
Cow Wish Bottom Nitrate
In response to rising nitrate concentrations, the company will design and install a solution for addressing the nitrate risks at Cow Wish Bottom water treatment works. This scheme will be completed by 31 December 2030 and will benefit 24,631 consumers.
United Utilities
Royal Oak PFAS
The company have identified PFAS in tier 2 in the raw water source and will be designing and installing a process solution to address the risk of PFAS entering supply. This will be completed by 2032 to the benefit of 235,677 consumers.
Wickenhall PFAS
As with Royal Oak, above, the company have identified PFAS in tier 2 in the raw water source. It will design and install a process solution to address the risk of PFAS entering supply. This will be completed by 2031 to the benefit of 62,991 consumers.
Wessex Water
PFAS Catchment Management
In an enhancement to its overall PFAS strategy, Wessex Water will develop a hydrogeological model for all of its catchments. The company will then use this model to inform, develop and implement a risk-based PFAS catchment monitoring strategy. The scheme will be completed by 31 December 2030.
Charlton PFAS
The company will complete the planning and design of a new treatment facility at Charlton works, to address risks of PFAS in the catchment. This will involve procuring land and gaining the planning permissions required, creating a detailed plan with timescales and then completing the installation and commissioning of the chosen treatment solution. The scheme will be completed by April 2036 and will benefit 6,735 people.
Tucking Mill PFAS
The company will complete the planning, design and procurement arrangements to upgrade the existing Granular Activated Carbon (GAC) treatment at Tucking Mill treatment works, to address the risk of PFAS in the upstream catchment. The company will implement the upgrades to the GAC treatment and complete trials to ascertain the most effective treatment option for PFAS. The company will then implement the most effective treatment solution identified. The scheme will be completed by January 2032 and will benefit 199,598 people.
Upton Scudamore PFAS
The company will complete the planning and design for a treatment solution for PFAS risks at Upton Scudamore treatment works. The company will develop a detailed plan with suitable timescales, followed by completing the installation and commissioning of the chosen treatment solution. The scheme will be completed by April 2036 and will benefit 149,594 people.
Table 3: AMP8 Legal instruments issued in Q3 2024
Acknowledged Actions
In an example of better regulation in practice, the Inspectorate has been working closely with Ofwat on the enhancement schemes. The result is that Ofwat have not placed separate Price Control Deliverables (PCDs) on the Inspectorate supported schemes and have instead set the success criteria as successful completion of the relevant Inspectorate legal instruments. The Inspectorate will monitor the delivery of legal instruments through our routine work and will provide additional feedback to Ofwat in respect of progress.
As part of this arrangement, Ofwat asked the Inspectorate to also manage those schemes which had been funded but were commended for support by the Inspectorate rather than receiving full support in the form of a legal instrument. Schemes are usually commended for support because the Inspectorate supports the need to complete them, but because the case for an imminent risk had not been demonstrated, or the scheme falls outside of the scope of our regulatory remit, we cannot give full support in the form of a legal instrument. The Inspectorate therefore adopted the same approach as used to monitor the Green Economic Recovery schemes, which is put into Acknowledged Actions.
Acknowledged actions are not legal instruments and as such, have no legal status. They are a set of actions that companies commit to deliver and which the regulator (the Inspectorate, in this case) formally acknowledges. Acknowledged actions are assigned a reference number, similar to a legal instrument reference number and are tracked using the legal instrument tracking processes by the Inspectorate’s enforcement team. They do not preclude formal enforcement action, should risks change in the future.
Companies were requested to provide a single, annual report on progress against these actions, timed to coincide with the annual reporting to Ofwat and an additional completion report at the end of each scheme to demonstrate its success and thereby benefit and value for consumers.
The following acknowledged actions were formally put into place during the third quarter of 2024.
Company
Scheme
Details
Dwr Cymru – Welsh Water
Catchment investigations
Improvement of catchment activities, including; improving understanding of risk, catchment knowledge, smart catchments with a digital twin to predict changes in raw water quality, research, collaboration with stakeholders to improve safeguarding of water supplies. This scheme will continue to 2030 and beyond as part of Dwr Cymru (Welsh Water’s) 2050 strategic ambition.
Severn Trent Water
Westwood / Dunhampton Cryptosporidium
Installation of Ultra Violet (UV) disinfection to mitigate Cryptosporidium and microbiological risks at Dunhampton source. This scheme will be complete by 30 April 2030 and will benefit 176,769 customers.
Far Baulker / Rufford Cryptosporidium
Installation of Ultra Filtration disinfection to mitigate Cryptosporidium and microbiological risks in the source water for the benefit of 236,040 consumers.
Wildmoor Cryptosporidium
Installation of UV disinfection to mitigate Cryptosporidium and microbiological risks in the source water for the benefit of 225,174 consumers
Rednal Cryptosporidium
Installation of UV disinfection to mitigate Cryptosporidium and microbiological risks in the source water to benefit 14,236 consumers.
Edgmond Bridge Cryptosporidium
Installation of UV disinfection to mitigate Cryptosporidium and microbiological risks in the source water, benefitting 149,509 consumers.
Laboratory Expansion
Expansion of laboratory for increased PFAS analytical capability.
Southern Water
Emerging contaminants
The company are designing and implementing an emerging contaminants study, to improve their understanding of where emerging contaminants are present and their concentrations. This will result in detailed plans for further monitoring and interventions in future asset management periods.
South Staffordshire Water
Disinfection resilience upgrades
The company are implementing disinfection upgrades at various sites inclusive of a proactive movement to UV treatment in order to mitigate the potential risk of raw water quality deterioration, as well as improving resilience. In total, the upgrades of the treatment woks covered by this programme will benefit 1,391,555 consumers.
South West Water
PFAS and other emerging contaminants
The company are designing and completing several workstreams to gain insight into quantifying and validating the risk of PFAS and other emerging contaminants. This will result in detailed plans for further monitoring and proactive interventions in future asset management periods.
Table 4: AMP8 Acknowledged actions in Q3 2024
Significant legal instrument revocations
In October 2016, United Utilities were served with a notice that formed part of the original transformation programme for the company. This notice encompassed all of its treated water storage tanks. The notice required the isolation, inspection and cleaning of all of these tanks, due to the high number that were, at the time, unable to be taken out of supply. As would be expected with such a large scope of a notice, it was altered several times along the way to account for difficulties encountered and additional works identified as needing to be done. The company was finally able to submit a completion report to the Inspectorate during the summer of 2024, and having been satisfied after assessment, the Inspectorate revoked the notice.
Completion of this notice represents a huge amount of work from the company, that has required consistent focus and investment of time and money for the last eight years. The Inspectorate was pleased at the continued effort put into this objective by the company. The result is a significant reduction in the risk being carried by the company in respect of its treated water storage assets. As well as reducing the risk of microbiological detections occurring in the future, it also ensures that when such detections do occur, the company will not be faced with some of the hard decisions companies have to take when faced with a public health risk from an asset in poor condition, but which cannot be taken out of supply.
Since this notice was served, similar notices have been served on several companies in order to achieve the same level of risk reduction (as reported in this series of reports).
In September 2018, Thames Water was served a notice, that formed a part of the company’s transformation programme. This large notice covered 95 treatment works, split into four sections, for risks associated with Cryptosporidium contamination. The first section of the notice required the company to review the type of monitoring in place at its treatment works, to understand appropriateness. The review concluded that large volume filtration using Idexx’s Filta-Max xpress system was an appropriate method for raw and treated groundwaters, as well as treated surface waters. The review was unclear, however, as to the value of moving away from calcium carbonate flocculation to large volume filtration for raw surface waters. This may be of interest to other companies, with similar water matrices and laboratory practices.
The second part of the notice required the company to complete a Hazard Review of the risk of Cryptosporidium entering the final water at all sites on a risk prioritisation basis. The hazard review was required to include compliance with the Expert Group on Cryptosporidium “Badenoch and Bouchier,” catchment surveys, a review of treatment processes for removal or inactivation of Cryptosporidium and a review of abstraction and reservoir management, amongst other items. The Hazard Reviews were submitted to the Inspectorate on a quarterly basis, beginning in July 2018 and continuing to September 2023. All were completed on time.
The third part of the notice required the company to use the outputs from the Hazard Reviews and reassess the requirements for continuous monitoring of Cryptosporidium for raw, in-process and treated water at all water treatment works. This began in March 2021 and was completed in November 2023, again on time. Findings from these reviews fed into the company’s Drinking Water Safety Plans, and informed sampling frequencies and requirements.
The fourth and final part of the notice required the company to use the findings from the Hazard Reviews, and identify any additional risk mitigation, or enhancement of current mitigation, to secure the long-term protection of public health. Some of the risk-mitigation implemented by the company was able to be done quickly, such as adding alarms or re-installing sampling cartridges. Other actions required long-term planning and investment, to mitigate the risks of Cryptosporidium, such as installing a second membrane plant at Datchet treatment works, or completing a slow-sand recirculation project at Kempton treatment works. Some risk-mitigation measures are being delivered under separate legal instruments, owing to the large amount of investment required, but all other mitigation work has now been completed. Ordinarily (as has been the case in other similar notices) the Inspectorate would expect to use the actions generated from the Hazard Reviews and serve a new legal instrument to ensure actions are captured and completed. This, however, was not needed in this instance, an indication of the commitment shown by the company. The notice remained the same version as when it was served, without the need to be changed. This is noteworthy, given its size and complexity, and again demonstrates the company’s commitment to mitigating the risks that this notice covered.
Risk assessment
There were personnel changes within the risk assessment team; one inspector moved to the private water supply team, one inspector left to join the water industry, and a new inspector was welcomed into the team in August.
The Water Industry (Suppliers’ Information) Direction (the Information Direction) was published in July which incorporates regulation 28 reporting specifications. This enables better tracking of the reporting requirements for the industry and separates DWSP guidance from the requirements for provision of information.
Guidance on the Water Supply (Water Quality) Regulations 2016 (as amended) for England and Water Supply (Water Quality) Regulations 2018 for Wales specific to PFAS (per- and polyfluoroalkyl substances) in drinking water was published August. This guidance consolidates and supersedes previous PFOS/PFOA guidance (2021) and subsequent information letters regarding PFAS monitoring, risk assessment and reporting requirements, and expectations for AMP8 and beyond PFAS strategies.
Key changes to the PFAS guidance included a requirement to implement a risk reduction strategy to progressively reduce PFAS concentrations at tier 2 as well as tier 3 sites, the application of tiers to final water and raw water where there is no treatment in place, monitoring and reporting of the compound 6:2 FTAB added to the list of PFAS parameters and reporting of the ‘Sum of PFAS’. The latter two requirements must be implemented by 1 January 2025. The expectations of the PFAS Guidance extend to New Appointments and Variations (NAVs), these companies should exchange information and data and must also have a forward-looking PFAS strategy.
All PFAS chemicals of interest were listed in Annex C of the Information Direction. It is incumbent on companies to notify the Inspectorate should PFAS chemicals not listed be identified at concentrations above tier 1.
The risk assessment team attended the industry forum in September. The continuous collaboration with the industry that the forum enables is valuable and the Inspectorate is appreciative of water industry representatives’ time in attendance and the contributions to progress in DWSP.
Information was provided describing the above changes in the PFAS guidance and the ongoing work to provide the industry with new DWSP guidance. The DWSP guidance was produced in draft for Inspectorate review prior to being shared with the forum. At the forum meeting, companies were given an insight into details being included in the new guidance such as reiteration of the endorsement of the WHO water safety planning approach and expectations regarding it.
Clarification was given regarding hazards requiring assessment including the nitrate/nitrite formula (regulation 4(2)(d), Cryptosporidium, PFAS chemicals of interest and chlorate, all subject to regulation 4(2)(b). Other changes being written into the new DWSP guidance such as inclusion of delivery dates for additional control measures within regulation 28 data, timescales for submitting reactive DWSP updates to the Inspectorate should not exceed two months from the date of the event, compliance breach or other trigger were also discussed.
Based on the feedback from the industry, a small working group was set up with representatives from large, small companies and NAVs to address the comments received. This resulted in some amendments and updates to the guidance which should provide companies with additional support to meet their responsibilities under the Regulations.
There have been ongoing inconsistencies in the data submitted to the Inspectorate under regulation 28. Not all companies have reported hazardous events historically. The forum discussed how hazardous events could be reported to better enable the Inspectorate to understand the causes of risks and appropriateness of control measures. The visibility and reporting of risks carried forward from upstream assets was also discussed as an outstanding issue with relevance to reporting consistency. A working group was proposed to identify a common approach to these inconsistencies.
Feedback about response to recommendations was provided to the industry forum to clarify Inspectorate scoring of company responses to recommendations and demonstrate regulatory transparency. The response scoring and definition criteria were tabulated as part of the Inspectorate’s presentation to the forum. Other key points about this information were that the provision of information should satisfy Inspectors that companies’ actions are sufficient to prevent recurrence of an event or infringement and the importance of evidence from companies demonstrating actions taken was also highlighted.
The team will continue with a program of DWSP audits throughout the year with safety plans being audited against the Regulations.
Polycyclic aromatic hydrocarbons (total by calculation)
1
1
Radon
3
3
Sodium (total)
1
1
Taste (quantitative)
23
23
Total coliforms (confirmed)
58
30
88
Turbidity
1
1
Turbidity – indicator
5
5
Total
61
13
35
316
425
Table 5 – Compliance failures taken from treatment works, reservoirs, supply points and consumers
Events
Company
0 (not an event)
1 (not significant)
2 (minor)
4 (significant)
4 (serious)
Total
AFW
5
2
2
9
ANH
1
8
5
3
17
BRL
2
1
3
6
CAM
1
1
DWR
3
4
5
12
HDC
1
1
1
3
ICW
1
1
IWN
5
2
7
LNW
1
1
NES
5
2
8
15
PRT
3
3
SES
2
2
SEW
2
2
SRN
5
5
SST
2
1
6
9
SVT
8
7
6
21
SWB
4
3
6
13
TMS
3
5
9
17
UUT
3
4
11
18
WSX
4
3
7
YKS
3
7
4
1
15
Total
1
62
44
76
1
184
Table 6 – Water quality events affecting treatment works, reservoirs, supply points and consumers
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