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Consumer contacts

The acceptability of drinking water is ranked by consumers as their top priority, and can be affected by several factors including its appearance for example, discolouration or aerated, or the taste and/or odour. Most acceptability complaints are caused by a black, brown, or orange discoloration of water which are caused by elevated concentrations of manganese, iron, and aluminium.  

Whilst these metals are rarely at a concentration which is harmful to health, they can and do cause widespread rejection of water based upon appearance. The expectation and priority of a consumer is for their water to be clean and safe, and therefore, events which cause discolouration are highly disruptive to consumers with the inevitable drop in confidence which follows. The Inspectorate takes these events very seriously and many companies have notices in place to focus on the root causes of discolouration. 

In February 2024 the Inspectorate issued information letter 01-2024 ‘Annual Provision of Information on Consumer Contacts’ which set out new requirements for companies to report a greater level of detail on their consumer contacts which included the following additional requirements: 

  • A unique reference for each contact
  • Details of the district metered area the contact is located in
  • The date and time of the contact
  • The location of the contact
  • The mode of contact
  • Whether the contact is a repeat within a 12-month rolling period (that is a new occurrence or ‘case’ of a similar issue from the same consumer)
  • If the contact is associated with a notifiable event, and the associated event reference number

Information regarding multiple contacts, for example if a consumer reports more than one drinking water quality concern during a contact, is also recorded.

The data submitted from companies in 2025, covering 2024 is the first submission to include this additional data. To maintain continuation of a comparable data set and monitor industry performance and progress, the new data return allows companies to continue reporting multiple descriptors as either primary or secondary contacts as they have before, with only primary contacts used to monitor ongoing performance.

In England in 2024 there were 70,507 consumer contacts regarding acceptability of drinking water, reported to companies wholly or mainly in England. This is a rate of 1.21 per 1,000 population. The table below shows the number of contacts received for each type of complaint for English companies, with contacts relating to discoloured water (brown, orange, black) being the most common reason.

CategoryContacts
Appearance – Brown black orange28,974
DWQ Concern – Lead and analysis7,486
Appearance – White Air8,386
Taste Odour Other8,606
Taste Odour Chlorine6,768
Appearance – Particles6,427
Illness – Gastroenteritis5,330
Appearance – General Conditions5,516
Taste Odour Earthy Musty3,736
Illness – Skin1,527
Appearance – Blue Green1,074
DWQ Concern – Lifestyle769
Appearance – White Chalk491
Taste Odour Petrol Diesel447
Illness – Oral443
Illness – Medical Opinion303
Appearance – Animalcules252
DWQ Concern – Campaign197
DWQ Concern – Pets Animals242
Table 20 – Number of consumer contacts in 2024

Discoloured water 

Discoloured water usually occurs following flow changes in the drinking water network which re-suspends existing sediment in the mains pipework. Occasionally, due to planned work such as valving, or following bursts or periods of high demand, flow changes can occur. Flow changes, which can result in resuspension of sediment, should be managed by companies. In 2024 around 40 events in England were reported where brown, black or orange discolouration was experienced by more than one consumer at the same time.

The Inspectorate reviews consumer contact data for discoloured water contacts on an annual basis. Companies whose performance is poorer than the industry average are investigated, and enforcement action taken where necessary. Companies with legal instruments in place have a higher risk of discolouration and are:  

Companywide discolouration performance is considered when serving notices, in addition to individual water supply zone performance. When completed, these legal instruments will improve water quality to consumers supplied by these companies. 

The number of contacts reporting discoloured water (brown, orange or black) across the industry (England and Wales) over recent years has been decreasing, however 2024 has seen a slight deterioration on the previous year’s performance. In England, the rate follows a similar trend and has also seen a slight deterioration in 2024, from 0.4 contacts per 1000 population in 2023 to 0.42 contacts per 1,000 population in 2024.  

The England company ranking can be seen below. Of note is the position of South East Water, who have seen a deterioration from 9th worst performing company in 2019, to now being 3rd worst performing. 

Whilst other poorly performing companies are improving, the performance of South East Water has not, resulting in them moving up in the ranking over time. 

Following the industry trend, most companies under discolouration notices have reported a slight deterioration in contact rate in 2024 compared to that in 2023. However, Southern Water, United Utilities and Wessex Water have improved their contact rate in 2024, with United Utilities and Wessex Water showing a continuing downward trend.   

South West and Bournemouth are on a deteriorating trend since 2022, now at a higher contact rate than five years ago. South West and Bournemouth remain the worst performing company in England. 

Events related to consumer acceptability 

South West & Bournemouth discolouration event

In July 2024, South West and Bournemouth Water reported a discolouration event following a burst on a 20 inch section of the Cornwall spine main located near Summercourt in Cornwall.  The spine main is part of a strategic dual main system which feeds large parts of Cornwall. The spine main at this point supplies approximately 84,700 properties in the areas of Padstow, Truro, St. Columb, Perranporth, St. Agnes, Redruth, Carbis Bay. Following the burst the company undertook network changes to minimise the impact of the burst and isolated the section of burst main to complete repairs. The repairs were completed the same day and the company began to recharge the main with flushing completed and turbidity being monitored in the network as part of the company’s risk assessment. The main was fully back in supply in just under 24 hours of the burst occurring, with the network returned to its normal operating configuration shortly after. The impact of the burst caused both loss of supply and discolouration, with around 800 consumers contacting the water company to report discoloured water and around 500 to report no water. The burst occurred during a time when a service reservoir was out of service for planned repairs, which also caused a loss of supply, low pressure and media interest event in the downstream network. Following these events, the company undertook a root cause analysis which identified the need for the service reservoir to be in service during high demand periods such as the summer. The Inspectorate made recommendations to the company surrounding its resilience plans in the areas and consideration of the need for the service reservoir to sustain demand when undertaking planned work and on the triggering and provision of alternative water supplies as stipulated in the Emergency Planning Guidance.

These events demonstrate the scale and impact that a strategic mains burst can have on the downstream network, compounded during a period when an asset is out of service for planned maintenance. The function of strategic mains and how these support downstream assets and supply systems should be fully understood and companies should have appropriate risk assessments, resilience and contingency plans in place to minimise impacts to consumers for water quality and supply, should an event occur.

United Utilities Cumwhinton discolouration

Also in July 2024, a burst main on a cast iron trunk main near United Utilities’ Cumwhinton treatment works resulted in over 300 consumers contacting the company to report discoloured water. 

A technical post-incident review identified discrete pockets of consumer contacts, each with individual root causes that led to the resuspension of historic mains sediment within the network. Continuity of supply to customers was maintained through the use of reservoir storage, alternative supply vehicles injecting into the network, and multiple network interventions. Targeted flushing activities were also undertaken in response to discolouration contacts. As part of the learning from this event, suggestions were given to the company around the internal cleaning and inspection of compartment 1 of Cumwhinton (Combined) reservoir, and to review and add the affected DMAs to the company’s flushing programme for 2025/26.

Companies should strengthen their approach to managing discolouration risk by applying the lessons from this event, specifically targeting mains sediment control, network interventions, and proactive reservoir maintenance. With the aim to reduce the future risk of discolouration and improve resilience against similar incidents in the future.

Similar to discoloured water contacts, the rate for total taste and odour contacts for the industry has gradually reduced year on year, although in 2024 this rate has deteriorated to 0.25 per 1,000 population from 0.22 in 2022 . In England, this rate is slightly lower in 2024, at 0.23 per 1,000 population, however this is still an increase from 0.21 in 2022.

United Utilities – Cheshire and Merseyside customer contacts taste and odour event

United Utilities received a total of 968 contacts, of which 786 were for taste and odour, between 5 August and 31 August 2024, from consumers in water supply zones (WSZs) supplied by Huntington and Sutton Hall water treatment works. Huntington and Sutton Hall works abstract from the River Dee and supplies a combined population of 1,904,568 across Merseyside and Cheshire. Following investigations, the company concluded that the likely root cause of the taste and odour to be point source pollution of the River Dee with 2-isopropyl-3-methoxypyrazine (IPMP). The company identified that a dispensing system, which had an automatic wash system was discharging to surface drainage. Although the system was installed in November 2023, it was moved and connected to the surface drainage on 27 May 2024. On finding the source of the IPMP, the company worked to rectify the drainage arrangements on 23 August 2024. 

There are no previous examples of contamination caused by this compound within the industry. The DWI concluded that the company breached the limits set out in Schedule 1 of the regulations which requires that there must be no abnormal change in taste and odour.

The company were also quick to implement the scientific investigations in August 2024 that lead to the identification of IPMP and the tracing of the source.

The Inspectorate would expect all water companies to implement learning from this event across all their catchment risk assessments.

Following the conclusion of the event the Inspectorate audited United Utilities’ Huntington and Sutton Hall works in November 2024. The Inspectorate requested a process controller to be present during the two-day audit, however, contrary to expectations, this did not occur. The Inspectorate reminds companies that it is always beneficial to have competent, trained and informed site operators present during a works audit to answer any questions regarding the day-to-day operation of the site. 

Seven recommendations were given in total, with several under regulation 27, including to update the site risk assessments with site specific control measures; to develop a procedure and process to regularly verify the powdered activated carbon (PAC) dose at both Huntington and Sutton Hall works; to implement regular cleaning of all clarifiers and clarifier inlet channels at Huntington works due to the significant build-up of floc and sludge; to implement better control measures, to prevent contamination from buffers and reagents; and for regular maintenance and cleaning to be undertaken on the Actiflo streams at Sutton Hall works.

Enforcement was initiated under regulation 28(4) at both sites for shortcomings in the PAC dosing, filtration maintenance and management, and contact tank inspection philosophy at Huntington works and for deficiencies in the PAC dosing system and filtration management at Sutton Hall works.

Severn Trent Water – Chester customer contacts taste and odour 

The River Dee also supplies water to Severn Trent Water’s Boughton works, which supplies Chester and the same compound that caused the issues outlined above also occurred here. On 6 August, United Utilities advised Severn Trent Water of a significant increase in musty taste and odour complaints received from consumers supplied by United Utilities’ Huntington works, located upstream.

In response, Severn Trent Water merely reviewed the number of consumer complaints in its own supplies, which was low and initially took no further action. United Utilities subsequently advised that the compound detected was IPMP and Severn Trent Water supported a catchment investigation sampling on 24 August. United Utilities advised Severn Trent Water on 29 August 2024 that the likely source of pollution was a dairy farm upstream of Huntington works.

Severn Trent Water subsequently implemented hourly odour checks at the River Dee intake and the final treated water point at Boughton works, alongside further sampling for a suite of ‘musty causing’ chemical compounds, including IPMP. However, the limitations of the IPMP method meant that it was over 30 times less sensitive than required to detect odour breaches at the threshold level.

Sample results between 20 August 2024 and 10 September 2024 reported:

  • Indicative concentrations of IPMP up to 1.486 ng/L from samples collected throughout Boughton works and the Chester supply system between 21 August and 28 August 2024.
  • Concentrations remained significantly below the compound’s 24-hour health-based limit of 135 µg/L (equivalent to 135,000 ng/L) and 7-day health-based limit of 54 µg/L (equivalent to 54,000 ng/L).
  • Sample results indicated that the concentration of IPMP decreased in the raw water (<0.34 ng/L) from 23 August 2024 onwards and levels were higher in the downstream network, suggesting the potential peak of the pollution had passed through the works to the downstream network.
  • Earthy or musty taste and odour detections for samples collected from Boughton works final and the Chester supply system between 22 and 29 August 2024.
  • All the other sample results were satisfactory, apart from a microbiological detection caused by a dirty tap.

The main treatment control for IPMP at Boughton works is granular activated carbon (GAC) filters. Although Severn Trent Water considered the GAC treatment stage was meeting all site performance targets this did not effectively address the treatment issue. The company could identify no other treatment optimisation options to increase the removal of IPMP at Boughton works.

The company removed some musty water by flushing targeted areas to reduce taste and odour impact based on consumer contacts from 22 August 2024 to 30 August 2024 when the flushing ceased after a low level of consumer contacts for three consecutive days.

The Inspectorate audited Boughton works in November 2024 and identified the following relevant issues.

  • The company’s GAC replacement/ regeneration plan is risk based considering pesticide removal. The effectiveness of taste and odour removal is not considered.
  • Severn Trent Water’s policy to regenerate the GAC media on a five yearly basis was not always achieved. The regeneration dates are clustered and therefore there is a risk of exhaustion across the whole works at similar times. Two of the six beds exceeded the five year threshold.
  • The design assumptions for iodine number and empty bed contact time do not appear to be in line with good industry practice.
GAC regenerationPrevious regeneration date Most recent regeneration date
GAC 1 July 2015 January 2021 
GAC 2 August 2018 January 2020 
GAC 3 July 2015 March 2020 
GAC 4 September 2015 February 2020 
GAC 5 December 2015 February 2022 
GAC 6 January 2016 November 2020 
Table 21 – GAC regeneration at Boughton works at the time of the event. 5 yearly intervals exceeded on GAC1 and GAC5 

73 consumers complained to the company and the Inspectorate sent questionnaires to the affected households. A majority of respondents reported that they had stopped drinking the water and five had not restarted using it. Consumers were critical of Severn Trent Water for poor communication during the event with many unable to find information on the company’s website and having to rely on social media or call the company directly for updates. Consumers also reported their frustration in a lack of feedback on the cause of the musty taste with speculation falling on farmers spreading chemicals on the land or a demolished restaurant on the River Dee, neither of which was the cause. Consumers acknowledged text messages sent to close the event but would have appreciated more information on the root cause, the pollutant, and the potential health impacts. The Inspectorate is considering further enforcement of the company for this event.

Companies should learn lessons from this event, in particular the need to keep consumers appropriately informed and the need for prompt and appropriate actions to address water quality risks as soon as possible.

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