Drinking water 2024 Private water supplies in Wales
Published 11:24:37 BST 9 May 2025
Key headlines
A private water supply is any water supply which supplies one or more properties, that is not provided by a water company. Around 2% of the population in Wales use a private supply, which can originate from a range of sources including boreholes, natural springs, and water courses.
Private water supplies are found across most regions of Wales. Higher numbers are found in rural areas where connection to the public mains network may be difficult.
Figure 1.1 shows the density of the supplies across Wales:
In 2024, local authority records reported a total of 14,904 private supplies in Wales (14,786 in 2023). This only represents the supplies that are known to local authorities, and it is estimated that there are a further 41,764 supplies (Welsh Government, 2021) which are not registered with local authorities. Reporting on the quality of private water supplies is therefore potentially only representative of a quarter of private water supplies in Wales.
A private supply is one which is not connected to the public mains of Dŵr Cymru Welsh Water or Hafren Dyfrdwy in Wales. Typically, these provide water to approximately 2% of the population covering not just domestic supplies to households but also those to commercial premises such as farms, bed and breakfast accommodation, holiday lets, hotels, sporting clubs, manufacturers and other businesses. The contribution to the economy as well as the health and welfare of a small but notable population of over 67,000 is significant.
The standards and principles of regulation are the same for both public and private supplies, in order to protect public health equitably, regardless of the source of the water supply. The expectation is that the level of quality should be the same as public supplies, however, small private or community supplies are often of a poorer quality, as evidenced by the relative numbers of indicators of faecal pollution. E. coli was found in 8.97% of tests, compared with approximately 0.01% of tests of public mains supplies.
The reasons for this are complex but their small scale is one of the main challenges. The cost and resources required can be disproportionate when maintaining a small supply. For instance, technical knowledge covering geology and catchment science, borehole construction, treatment, and distribution engineering as well as water quality and risk assessment are highly specialist skills which are often inaccessible to private supply users, but are essential for the appropriate design, maintenance and operation of a private supply. These challenges can be exacerbated by property and ownership arrangements where a source may not be in the control of the user, and it may not be known with whom responsibility for the running and maintenance of the supply lies. Sometimes no-one accepts responsibility for a supply, leading to its neglect. In these instances, necessary safeguards to protect water quality, such as a lack of adequate maintenance and poor management practices, can be absent.
The principle of water supply regulation is one of self-regulation by owners/users/controllers, and independent scrutiny by the regulator, which for private supplies is the local authority.
Environmental health staff of local authorities are essential to regulating private supplies. They have a legal duty to keep a record of those supplies that are known and to conduct water quality and sufficiency risk assessments. Risk assessments are fundamental to identifying risks, and how these might be observed, managed, and controlled though a plan to protect public health and sufficiency. This helps users become better informed to manage supplies safely and, where necessary, carry out improvements to mitigate any risks identified to water quality and supply. It is becoming ever clearer how vulnerable some private water supplies are as the climate changes, and this is evident by the increasing numbers that run dry in periods of drought and those being affected more acutely by environmental pollution. Risk assessment should identify these supplies, and contingency plans should be established. This vulnerability extends to include supply interruptions which may be caused by infrastructure failures such as pipe bursts. The lack of resources to quickly react to these failures by completing fixes and replacements, or to provide suitable alternative supplies utilising existing pipework or via other means such as tankers and bottles, means that general resilience of these supplies is poor.
In 2024, due to software incompatibility that caused a problem with the reporting process, the Inspectorate is unable to include test results for the indicator parameter colony counts (number per 100 mL at 22 degrees centigrade). In 2024, 4.15% (1017) of 24,512 tests by the local authorities in Wales were found not to be meeting one or more of the standards for wholesomeness. Figure 1.2 shows that overall, there has been a reduction in tests failing the regulatory standards, however, there has been a slight increase in 2024. These figures must be caveated because the overall number of tests carried out is below that which would be expected for the number of private supplies recorded in Wales. Due to the data error, the Inspectorate has removed all data associated with colony counts across all years in all charts within this report. This allows the data to be comparable over time for this year’s report, however, this means that a comparison should not be made between this year and previous years’ reports.
Figure 1.2 Percentage of tests failing to meet the standards for wholesomeness and the number of tests
At least 7.39% of tests in Wales during 2024 showed faecal contamination, with 8.97% (210 of 2,342) of samples tested found to contain E. coli and 7.39% (153 of 2,071) containing Enterococci. These organisms are almost exclusively found in faeces, indicating a potential danger to the health of those drinking this water.
The percentage of samples collected from supplies found to be contaminated by E. coli and Enterococci, in the period 2014-2024 is shown in figure 1.3.
Figure 1.3 Percentage of supplies samples in 2014-2024 found to contain E. coli or Enterococci
Figure 1.3 shows an increase in the number of tests in 2024 found to contain E. coli and a decrease found to contain Enterococci. The number of tests finding faecal contamination in private water supplies had plateaued and now appears to be worsening. An investigation into supplies found to be containing E. coli would need to be conducted to understand possible reasons why. For the last two years, the number of E. coli tests resulting in a positive detection has risen. There are a number of plausible explanations for this, such as local authorities entering a phase of increased activity, or supplies not previously being sampled, being tested for the first time. An investigation would need to be conducted to determine the reason, however there is no overseeing body within the Government to carry out this function. It must be noted that the testing regime is not uniform year on year, therefore it is expected and can be seen that there is a backdrop of fluctuating sample numbers and a similarly fluctuating number of failures which may be influenced by sample numbers and the sites from which they were taken. Looking at Enterococci alone, 117 supplies had one or more positive tests. Summing up the number of consumers at private supplies where E. coli and/or Enterococci have been found equates to 177 supplies where faecal contamination was found in the supply, with 1,884 people drinking this water.
One of the key principles of the Private Water Supplies (Wales) Regulations 2017 (the Regulations) is to carry out a risk assessment to establish whether there is a potential risk of supplying water that may be unwholesome or would constitute a potential danger to human health. The Regulations have advanced from the compliance-based methodology of end point monitoring, to minimise the dependency on a sample which may be as infrequent as once in five years providing less assurance of a safe and secure supply. Risk assessments are a proactive approach to identify the risks, which are often visible to the trained and competent assessor, resulting in simple action to put a method of control in place.
The importance of risk assessment will become more apparent as supplies are now reaching the point where there are more than three years’ worth of sample results allowing some to qualify for a potential sample frequency reduction for some parameters. When sampling frequencies are reduced, risk assessment will be the primary mechanism for quality and sufficiency issues to be identified and mitigated. In Wales in 2024, 17 out of 1463 regulation 9 supplies were subject to reduced testing frequencies. Local authorities may reduce sampling frequencies for any parameter apart from E. coli, provided three year’s test results show concentrations of the parameter at less than 60% of the standard. They may also cease testing altogether for parameters apart from E. coli, provided concentrations are less than 30% of the standard for three years. In both cases, the supplies’ risk assessments should indicate that there is no risk of these concentrations worsening. Additionally, the supplies should have a level of periodic testing, plus the required reviews of their risk assessments in order to identify any likely or actual change in risk or concentrations over time.
Point of use testing will remain a useful part of monitoring when measuring efficacy following a risk assessment, or more widely as a measure of general improvement or otherwise of an intervention strategy.
Each local authority must carry out or review a risk assessment of each qualifying private water supply system in its area at least every five years, or earlier if it is considered that the supply presents a risk. The Inspectorate has developed a set of risk assessment tools to help local authorities comply with their duties under regulation 6. These can be found on the Inspectorate’s risk assessment web page. A Microsoft Teams forum has been set up to facilitate training and videos are available through this group.
Local authorities report information on risk assessments and enforcement action to the Secretary of State in two ways; in the annual data return, and through summaries of risk assessments. Also, throughout the year, they must submit copies of notices served.
To date, the numbers in the annual data returns have never matched the number of documents received, with under-submission of risk assessment summaries and notices being a consistent issue. Some explanation is provided in the following section; however, local authorities are reminded that documents can either be redacted or sent by a secure file transfer to preserve data privacy.
Where any private supply of water intended for human consumption constitutes a potential danger to human health, the local authority must serve a regulatory notice on any or all persons involved with the supply. The main aim is to protect public health, so timely action is essential.
The local authority must consider the risk assessment, all the relevant local circumstances, and any advice from Public Health Wales. Any site-specific local agreements, covenants or deeds specifying responsibilities for specific aspects of the supply, or its management should be considered.
The 2024 data indicates that across Wales, the number of regulation 8, 9, and 11 private supplies that had been risk assessed within the previous five years was 1,280, covering 45.1% of these private supply types. In 2023, it was reported that 1,354 supplies of these types had an in-date risk assessment. Therefore, the total number of private supplies with a risk assessment which has been conducted within the last five years, where required by the Regulations, has reduced for a second consecutive year.
However, as the actual number of supplies reported in the data return has also reduced, the overall percentage of supplies with an ‘in-date’ risk assessment remains relatively static. This suggests that local authorities are only completing enough risk assessments to maintain the current percentage coverage, as risk assessments require review every five years.
The percentage of supplies which have never had a risk assessment has reduced from 18.2% to 12.7%, which is an improvement. However, the percentage of supplies with a risk assessment that was conducted more than five years ago has increased from 36.4% to 42.1%. In summary, for local authorities to attain and maintain 100% coverage, the rate of completion of statutory risk assessments will need to increase significantly.
Figure 1.4 Risk assessments at regulation 8, 9 and 11 supplies
In 2024, where a sample was taken for E. coli, this parameter was found in 40 supplies without a risk assessment or where a risk assessment was not carried out in the last five years. It remains disappointing that in these cases, a sample result revealed the contamination, because the consumer would have been unsuspecting and would not have been acting to protect their own health prior to the water being tested.
The better-practice approach is for a risk assessment to identify sources of contamination and pathways to the supply. This approach should identify all potential contaminants and not rely on the results of a spot sample which cannot be guaranteed to detect all contaminants at the point a sample is taken. The contaminants being tested for may be limited, and concentrations of those which are tested for, may not be at their worst-case. Most worrying is that where samples are taken in the absence of a risk assessment, the consumer continues to use the water for drinking and cooking while the samples are analysed. Where a local authority receives a positive result for bacteriological tests in the absence of a supply risk assessment, the supply should be prioritised in the local authorities’ risk assessment programme.
In this 14th year of reporting against this current regulatory framework, local authorities are still not fully delivering their statutory duties which aim to protect public health.
Understanding the state of private supplies in Wales relies on the provision of information and data by local authorities. In turn, the analysis of this information allows national reporting to direct policy change in pursuit of improving the quality of private supplies. However, this has been impeded by late or absent returns to the Inspectorate of sample data, summaries of risk assessments and notices which have been served. To remedy this issue and to modernise the risk assessment tool provided to local authorities, the Inspectorate commissioned a new online system to replace the Excel risk assessment tools, and parts of the information submission requirements. The plan to roll out the system in a beta phase, was put on hold during 2022. Due to significant challenges with the partially developed online system, the Inspectorate has concluded that a bespoke system utilising Defra’s Digital, Data and Technology Security service will be required. However, difficulties securing funding will affect the Inspectorate’s ability to collect private water supplies data going forward.
During 2024, the Inspectorate gathered data through the annual data return which is a statutory reporting requirement of local authorities.
Under regulation 16 of the Regulations, local authorities must keep records of every private supply in its area and submit these to the Inspectorate by 31 January each year.
For the reporting year 2024, a submission was received from all 22 local authorities in Wales.
In 2024, local authorities carried out 24,512 analyses of private water supplies samples (not including colony counts). This is an increase of 4.90% on the previous year (23,366) indicating a recent improvement in overall sample numbers but this is still some 5% less than the numbers taken in 2019 and pre-pandemic. Figure 2.1 shows a general increase in samples taken since 2020, with 2020 representing an exceptional year due to the impact of the pandemic. This increase may indicate that more resources are being allocated to private water supplies sampling and testing.
Figure 2.1 Number of tests from 2014 to 2024 (without colony counts)
When analysing the test data to produce this report, the Inspectorate identified an anomaly. There was a much greater number of colony-count failures than previous years. The standard for colony counts (specifically three days at 22 degrees centigrade) which is an indicator parameter, is ‘no abnormal change’. There is therefore no ‘prescribed concentration or value’ (PCV). It is the responsibility of local authorities to determine what would be an abnormal change for any particular private water supply. An abnormal change may indicate a problem with the quality of the supply. In public supplies, it is not uncommon to see colony counts between tens and hundreds, which are a stable background levels for a supply or perhaps an asset such as a treated water reservoir within distribution. Investigating this anomaly further, the Inspectorate found that a problem with the validation macros of the data return Excel template meant it would not allow a colony count value of greater than zero (in effect a count of one or more) to be entered as a ‘pass’. Unfortunately, many local authorities decided the best course of action was to change these results to a ‘fail’ to eliminate the spreadsheet error. This was unnecessary, as the database validation routine was working correctly, and would have accepted these results as passing tests, had the Excel template been uploaded. The Inspectorate will investigate options to rectify this incorrect data with local authorities affected, during 2025. Due to this data error, colony count test data and information have been removed from charts and figures in this report.
At an aggregate scale, it is clear that private water supplies are not being tested at the frequencies required by the Regulations. It is vitally important for the regulatory testing regime for a supply to be determined and then met each year, or every five years, as appropriate. This validation monitoring provides a baseline to measure the overall quality of those supplies and the effectiveness of mitigation measures. Other sampling which could be called ‘investigatory’, can be recorded as such on the annual data return. Figure 2.2 illustrates the issue of incorrect testing frequencies for one parameter, E. coli. At regulation 9 supplies, E. coli should always be tested at the Group A frequency stipulated in the schedules to the Regulations. Samples taken as group A must be recorded in the data return as such.
In 2024, 67% of regulation 9 supplies were tested at the correct frequency for E. coli according to the volume supplied which is a slight improvement on 64.7% in 2023, with a further 9% of supplies sampled for E. coli at a greater frequency than the Group A parameter frequency required by the Regulations. However, the remaining 24% had fewer tests than required by the Regulations, 2% being under-sampled and 22% not being sampled at all. In 2023, 19.2% of regulation 9 supplies were not sampled at all for E. coli, showing a reduction in regulation 9 supplies testing in 2024.
Figure 2.2 Regulation 9 supplies tested for E. coli at Group A frequency
The Inspectorate attends various regular meetings and events each year. A common point of discussion at these meetings is risk assessments and test data from third parties. The Inspectorate can confirm that it does not receive data or any other information on private water supplies from third parties. The only data submission process in place is the one managed directly with local authorities.
If local authorities are using third parties to conduct private water supplies sampling and testing, the requirement of schedule 4 part 1(5) of the Regulations for an agreement (contract) to be in place must be met. This contract between the local authority and the provider must ensure that the requirements of the Regulations are met, and that any breach of those requirements is reported to the local authority within 28 days.
While there is no similar direct provision in the Regulations for local authorities to use third parties to conduct risk assessments, the very nature of conducting a holistic risk assessment means drawing on the information and knowledge of others who are informed about the supply. Though, third parties may be major contributors to the risk assessment process, local authorities still carry the responsibility for the risk assessment overall, and are the only entity empowered to act in response to the risk assessment’s conclusions.
Local authorities bear the sole obligation for reporting data and information to Welsh Ministers under the requirements of regulation 14 and schedule 4 of the Regulations, therefore the Inspectorate will not accept data or information from third parties, where no arrangement is in place.
Regulation 8 supplies would be the most common supply type that may involve a third party. Some of these onward supplies serve a large number of consumers, with the third-party distributors often being large organisations or companies. The Inspectorate has been involved in informal discussions when local authorities have cited that these third parties either refuse to share their test data or assure the local authority that test data is being shared with the Inspectorate. As the Inspectorate does not receive any data or information from third parties, this indicates a potentially large data gap which is likely due to missing third-party data.
Table 1 A summary of the percentage of samples failing for various microbiological and chemical parameters
The detection of specific indicator micro-organisms means that a supply is contaminated. When E. coli, Enterococci and to a lesser extent Clostridium perfringens are found, this suggests that the contamination may be faecal in origin. Faeces often carry micro-organisms including bacteria, viruses and parasites which are harmful to health and when a faecal indicator is found, this water should not be consumed. Table 1 shows that during 2024, in Wales, one in 11 private water supplies may be unfit for consumption and pose a risk to health containing E. coli. Whilst coliforms are not always a direct indicator of faecal contamination, they still indicate that there is a route for contamination to enter the supply and that contamination has not been removed by treatment. This was found in over one in eight tests. Protection of supplies from contamination is critical to protecting public health. Should a supply be found to contain the presence of faecal matter, the local authority is obligated to investigate in accordance with regulation 18 of the Regulations.
Taste and odour failures could be caused by the quality of the source water or develop as water passes though the distribution system. How consumers describe the taste or odour can help identify the cause, with descriptions such as ‘earthy’ or ‘musty’ pointing to possible algal problems in the source water and ‘woody/pencil shavings’ suggesting the presence of black alkathene pipework, to use a couple of examples. In 2024, the percentage of tests failing the standards for taste and odour were 1.43% and 1.82% respectively.
Lead and nickel were detected above the standards in 2.80% and 5.80% of tests respectively. For lead this is a decrease compared with 3.93% in 2023, 3.8% in 2022, 3.3% in 2021 and 2.1% in 2020. Lead is a neurotoxin that particularly affects children and can cause health effects in adults including chronic kidney disease, raised blood pressure and cardiovascular disease. Where lead is detected above the standard, local authorities must serve a regulation 20 notice to secure actions to protect the health of the consumers. The most robust long-term solution is the removal of any lead pipework, lead-containing fittings, and lead solder. The World Health Organization has recently published their refreshed technical brief on lead which can be found on its website.
Nickel is largely detected because of nickel plated domestic fittings such as taps. Notably, the percentage of failures is on an increasing trend which is also seen in public supplies as fittings containing nickel appear to be becoming more prevalent in properties. Sometimes the source is not obvious and could be under-sink mixers and temperature regulators. Consumers should be advised to replace these fittings where failures of the standard occur.
Iron, manganese and aluminium can be seen to have failed standards in 4.03%, 6.4% and 4.16% of tests respectively. All these metals can be found naturally occurring in source waters. Local authorities should consult with Public Health Wales to determine whether the concentration of these metals pose an immediate danger to health, and if so, serve a regulation 20 notice. Should the presence of these metals not be deemed a potential danger to health, local authorities can still act under section 80 to compel the relevant persons to make the supply wholesome and acceptable for all domestic purposes which includes washing and laundry.
Turbidity and colour are seen to have been found in concentrations above the standards in 2.19% and 2.29% of tests respectively. Turbidity can reduce the effectiveness of disinfection so a detection of turbidity in excess of the standard should trigger an investigation to determine the cause, followed by the appropriate course of action under regulation 20 or section 80 of the Water Industry Act 1991 (the Act) to carry out improvement actions. Colour detections are usually caused by compounds which arise from the catchment of the source waters and can be removed by suitable treatment processes. A short-term increase in colour and/or turbidity can be a result of high rainfall mobilising humic substances in source waters. If these short-term occurrences become more frequent, this may be a result of long-term changes in weather patterns.
The data return suggests that seven private supplies have had PFAS included in their regulation 6 risk assessment. This is an increase from three last year. Natural Resources Wales (NRW) has been writing to the owners and/or users of private supplies, when those sources, or nearby sources have been tested, and PFAS found. In parallel it writes to the appropriate local authority sharing those test results. If a local authority receives one of these communications, the relevant private water supply should be risk assessed and as appropriate, sampled and tested for PFAS. If the supply has any PFAS present in a concentration over 0.01 µg/L (micrograms per litre), the local authority should refer to the actions listed in the Inspectorate’s IL 3/2025 as a guide. If the supply is used for food production and PFAS levels are above 0.01 µg/L, the Food Standards Agency should be notified. The Inspectorate encourages local authorities to submit any PFAS data in annual data submissions. It is likely that most PFAS samples will be regarded as ‘investigatory’ samples. No test data was received from local authorities in Wales for 2024.
Water sample results provide insight into the quality of water at the time the sample was taken and can act as an indication that further investigation is needed.
Local authorities submit sample results to the Inspectorate annually. A small subset of results provided each year exceed the regulatory limits by a significant magnitude. Not all of these figures have a commentary provided with them in the data return, which would be an opportunity to explain exceptional circumstances.
One result over the limit of nitrite were reported at 10 times the limit at the consumer tap, which is 0.5 mg/L.
Nitrite is a health-based parameter as babies and younger children are susceptible to develop methemoglobinemia at concentrations of nitrite above the regulatory limit. This is because nitrite is an oxidant and so oxidises iron in haemoglobin (in blood) to methaemoglobin. This means that there is not enough iron in haemoglobin to transport oxygen in the body, resulting in symptoms such as a blue discolouration to the skin (known as cyanosis) and in severe cases, it can result in death.
Five results over 50 µg/L were reported for lead. There is no safe level of lead with the best solution to the presence of lead pipework being its removal. Lead is also present in brass fittings to varying levels. An investigation should be undertaken by the local authority for all lead results above the regulatory limit and should be considered at values below that.
Three results over 10 NTU were provided for turbidity. Turbidity indicates how much the light reflects within a sample of water. The higher the turbidity, the more difficult it is to fully disinfect the water. This includes with ultraviolet (UV) light. For supplies with high turbidity the risk assessment should consider the effectiveness of disinfection and the risk of disinfection byproducts. One pH result above the pH scale range (1-14) was also provided, which is clearly a typographical error as a result over 14 is not scientifically possible. Local authorities should ensure that data is sense-checked prior to being submitted to avoid situations like this.
In 2024, the percentage of private supplies which have an in-date risk assessment are:
• Private distribution systems (regulation 8 supplies): 47.8%.
• Large, commercial and public use (regulation 9 supplies): 57.3%.
• Small supplies and those as part of a domestic tenancy (regulation 11 supplies): 31.8%
In total, 2,841 supplies require a risk assessment, and only 1,280 (45.1%) have one that has not expired. For all supply types other than single dwelling supplies, local authorities have been required to complete risk assessments since 2010. It is concerning that, almost 15 years after the introduction of this requirement, there is a significant proportion (42.1%) where the risk assessment has exceeded the requirement for a five yearly review and a critical 12.9% which have never had a risk assessment.
In addition, supplies to untenanted single dwellings (regulation 10 supplies) are only risk assessed upon the owner’s request and 11.1% have in-date risk assessments.
In 2017, a change in the Regulations brought about the requirement for local authorities to provide a summary of the results of risk assessments to Ministers (in practice the Inspectorate), within 12 months of having carried out the assessment. During 2024, the Inspectorate received 53 risk assessment summaries from six local authorities in Wales, this is less than half of the total number of summaries received during 2023. 17 out of 22 local authorities in Wales that submitted data on private supplies did not meet the statutory reporting requirements regarding risk assessments in 2024. The Inspectorate would encourage local authorities to programme an annual exercise to submit the risk assessment summary pages to the Inspectorate, perhaps to coincide with the annual data return submission.
A review of the submitted risk assessment summaries suggests that some local authorities are only conducting reactive risk assessments following sample failures. Risk assessments and associated mitigation measures should be verified by sampling, and not the other way round. Data including sample results can be used to inform a risk-based prioritisation of risk assessments and it may be prudent to review risk assessments following sample failures. However, the risk assessment process must be a proactive one and not a process where risk assessments are only conducted where sample failures have occurred.
Protection of the source and the abstraction point were common root causes of risk identified as part of local authority risk assessments. The need for remedial actions to protect the source of a private supply from risk of contamination from livestock, slurry, pesticides, and septic tanks featured repeatedly on the summaries submitted to the Inspectorate. Similarly recurrent were actions required to secure spring chambers, headworks, and buildings from drainage issues, unauthorised access and vermin.
Ultraviolet (UV) systems are commonly used for disinfection in private water supply systems. The efficiency of UV systems used for disinfection are affected by the water quality and the flow rate through the system. High turbidity can shield pathogens from the UV dose and an improper unit for the required flow rate may result in an insufficient UV dose applied. Local authority assessors noted risks from a lack of maintenance, resilience and control in some systems. Common mitigations required the need for intensity monitors, alarms and shutdowns in case of unit/bulb failures, power interruptions, or high turbidity in the influent water which may inhibit UV disinfection. Such controls would reduce the risk of partially or non-disinfected water being available for consumption.
The absence of regular inspection, cleaning, and maintenance of water storage tanks was frequently flagged as a risk in the risk assessment summaries. For comparison, treated water tanks (storage reservoirs) are an integral part of public water supply networks. Water companies conduct external inspections annually to identify risks from ingress and contamination. Furthermore, water companies must conduct internal inspection, cleaning, and remedial maintenance at a frequency dependent on the risk and the quality of the influent water. Assets such as water tanks are not in stasis and require regular intervention to maintain operability.
Local authorities are required to send notices served under the legislation to Welsh Ministers (in practice the Inspectorate) in accordance with regulation 20 where supplies are a potential danger to human health. They may also serve notices under section 80 of The Water Industry Act 1991 where supplies are unwholesome and/or insufficient.
In 2024, the Inspectorate received 103 notices served under regulation 20 of the Regulations for supplies that were considered a potential danger to human health. The data return indicated that 145 were served, the number now not being sent to the Inspectorate is reducing. Two notices were served under section 80 of the Act according to the data return. Both were received by the Inspectorate.
Figure 2.3 Regulation 20 notices served versus notices submitted to the Welsh Ministers
Most notices are historically served in response to a failure of a microbiological standard, with a very small minority for failures of other standards. In 2024, 94 out of the 103 notices submitted were served for failures of microbiological standards.
Eight were served in response to failures of the standard for lead. One notice was associated with a supply that was deemed a ‘risk to health’ after completing a risk assessment.
The tenet of the Regulations is one of proactive risk assessment to prevent failures and a risk to health from ever being realised. Local authorities still appear to be predominantly reacting to sample results, rather than proactively eliminating the problems that would result in a sample failure. The use of a proactive risk assessment, and if necessary, a notice in this context, is to protect users before an incident occurs so they are not unsuspecting, and they can be responsible for protecting their own health. Table 2 shows the number and driver for 103 notices returned to the Inspectorate.
Table 2 Notices served
Reason for serving the notice | Number |
Bacteria | 94 |
Lead | 8 |
Risk assessment | 1 |
Total | 103 |
Notices served for microbiological drivers, numbered almost 100. The majority of these required treatment to either be installed or better maintained. However, 15 of notices provided short term measures only, such as boil water advice. It is likely that further measures would be needed in these supplies to ensure long term compliance with the Regulations.
Of the two section 80 notices served in 2024, one related to bacteria and the other related to multiple parameters of metals and pH.
For the notice relating to bacteria, the notice document indicated that positive samples for enterococci and E. coli had been recorded in the supply. Enterococci and E. coli are faecal indicators. Local authorities should ensure correct liaison with health authorities when determining what constitutes a risk to human health to make sure that the correct notice is issued.
Microbiological parameters | ||
|
2023 (%) |
2024 (%) | |
E. coli | 7.12 | 8.97 |
Coliform bacteria | 13.62 | 12.52 |
Enterococci | 7.73 | 7.39 |
Clostridium perfringens | 4.98 | 5.25 |
Chemical parameters | ||
Odour | 0.52 | 1.82 |
Taste | 3.92 | 1.43 |
Manganese | 6.65 | 6.4 |
Iron | 3.19 | 4.03 |
Aluminium | 1.68 | 1.55 |
Turbidity | 1.51 | 2.30 |
Colour | 1.86 | 2.29 |
Lead | 3.93 | 2.80 |
Nickel | 5.16 | 5.80 |
Pesticides | 0.00 | 0.00 |
Fluoride | 0.0 | 0.00 |
Others | 2.87 | 3.78 |
Nitrate | 0.95 | 0.86 |
Nitrite | 0.00 | 0.42 |
The Inspectorate continues to work with stakeholders on this complex subject. Inspectors have attended health liaison meetings across both England and Wales to speak about the change to the technical brief on regulation 8.
The Water Health Partnership for Wales has formed a ‘task and finish’ group to look at this topic and produce an agreed plan between local authorities and water companies on how to identify these supplies, then subsequently risk assess and sample them.
In 2022, the Inspectorate wrote to water companies reminding them of their responsibilities associated with the onward distribution of their supplies, particularly the requirements of section 74 of the Water Industry Act 1991. In 2025, the Inspectorate has sought a data return from water companies to ascertain progress with complying with these requirements.
The Inspectorate meets with the sampling certification body at least twice each year. This is primarily to monitor progress with the implementation of the scheme across the local authorities in England and Wales, and to identify any areas that are causing setbacks. The Inspectorate also attends training sessions to maintain an independent view of the scheme’s implementation. The scheme appears to be well embedded, and numbers of individuals certified continues to increase.
By the end of 2024, 115 local authorities had at least one certified sampler. Some of the remaining local authorities may use laboratory samplers, in which case they would not need in-house certified samplers. However, it is important to note that any samples taken and then analysed under part 2 (Monitoring) of the Regulations, must be done so in accordance with schedule 4 parts 1 and 2, which requires compliance with ISO 17024 or ISO 17025. Less than 1% of tests in Wales did not meet these requirements in 2024.
In 2023, the certification body introduced online training, reducing the need to find suitable training venues and removing the need for delegates to travel. The practical element of the assessment then follows and is carried out at a mutually convenient later date, in the field.
In February 2024, the certification body was audited by UKAS. No issues were raised.
The Inspectorate is satisfied that local authorities are generally complying with the regulatory requirement for samplers to be accredited under an ISO 17024 scheme (or equivalent). The scheme is now established and certification for the sampling of private water is an accepted necessary requirement. General feedback by delegates shows that the training is well received and provides essential training to maintain a common and recognised national standard.
Table 3 Status of certification under the ISO/IEC 17024 scheme
Number of samplers to date with valid/in date certificates. |
332 |
Number of samplers certified for the first time this year? |
54 |
Number of individual sampler 36 month re-certifications carried out this year. |
108 |
Number of trainees that failed the assessment first time during this year (including re-certifications). |
8 |
Number of samplers that have out of date certification. |
56 |
Number of sampler audits carried out this year. |
44 |
Number of certified samplers that were not audited within the 18-month window this year. |
19 |
Number of certified samplers to date have never received at least one audit. |
35 |
Number of local authorities with at least one certified sampler to date. |
115 |
The Inspectorate publishes a variety of case studies on private water supplies on its website. These cover a range of scenarios and subjects, which are largely derived from enquiries to the Inspectorate, either from local authorities or private water supply users. Some come from third parties, including lawyers, agencies, local councillors, and MPs. These case studies show and share the range and diversity of issues and circumstances that can come about in relation to private water supplies. The additional benefit of their publication on the Inspectorate’s website is to make available the learning that can be taken from them.
There were five case studies compiled in 2024. These can be found on the website at Drinking Water Inspectorate (dwi.gov.uk).
This case study describes the difficulties that arose during a period of insufficiency on a private supply that until 2017 was a public supply. The change from public supply to private supply was driven by ‘the demands of the regulatory framework’ (Ofwat, 2017) on the small supply with around 2,000 consumers. It was acknowledged at the time that consumers would lose their statutory protections under the Water Industry Act 1991, which includes alternative supplies should the mains supply fail. Currently, across England and Wales there are several small operations providing drinking water supplies as licenced suppliers. These include Albion Water with 3,000 consumers and ESP Water with 3855 consumers. In moving from being a public supply to a private one, it created several new challenges for those responsible for its maintenance and upkeep under private supply legislation. These challenges caused considerable impact to consumers during this period of insufficiency. These issues are not uncommon to shared private supplies and are exemplified in this case study. This case study also shows that whilst the switch from a public supply to a private supply resolved some of the problems that led to it, it created others which resulted in risk to consumers. These were not necessarily anticipated and/or proactively managed to prevent or mitigate these risks for a variety of reasons, when the switch was made. Often this is due to financial or resource limitations, or where the local authority has not used its powers to facilitate mitigation to prevent or adequately manage the risk.
In the Inspectorate’s report for the year 2013, it described the reasons why a newly installed private water supply serving a large regional hospital was never fully commissioned into use, despite the considerable costs it incurred. This case had some bearing on the revision of the Regulations in 2016. The Inspectorate revisited this case in 2024. It learned that the then new borehole at the hospital was never used as intended. Therefore, the considerable time, effort and costs were unfortunately and ultimately lost to this well intended project. This case study challenges the effectiveness of current private water supply regulation in protecting consumers in a way that is equitable to public drinking water supplies.
This case study exemplifies why prospective buyers of property served by a private water supply should consider any implications or potential risks associated with the supply prior to any purchase. Supply arrangements vary from one to another and the responsibilities in their management and maintenance are not always clear or documented. This can cause later difficulties and disagreement between the parties involved when situations change. Unfortunately, this is because any potential impacts these discrepancies may cause are often overlooked because robust checks are not made during the property conveyancing process. This case study shows one such example.
This case study concerns a regulation 9 supply providing water for domestic purposes to over 300 consumers. Sampling by the local authority highlighted a rising trend in arsenic concentrations, which presented a potential danger to human health. The local authority did not however investigate the root cause of the arsenic in accordance with regulation 16 or serve a regulation 18 notice to secure a permanent, long-term solution as the Regulations required them to do under these circumstances. Instead, when test results were over the maximum concentration stipulated in the Regulations, the site would be temporarily switched over to a back-up mains water supply until maintenance on inadequate treatment was completed. This reactive approach is contrary to the proactive risk-based approach that the Regulations require as it does not fully mitigate the risk or address the root cause in the long term to protect consumers.
It is not a legal requirement for consumers, owners or indeed anyone, to register private water supplies with the local authority. Many choose not to, whilst others are just not aware of the Regulations and/or that the Regulations place duties on local authorities to test and risk assess them (excluding that serve single dwellings exclusively). If a local authority is not made aware of a supply in its area, it cannot carry out its duties as required to protect the consumers of that supply. This presents a potential risk that can have unforeseen consequences as this case study illustrates.
The provision of technical briefings on the Inspectorate’s website is a fundamental role in relation to private water supplies currently fulfilled by the Inspectorate. The main purpose of this is to set out an interpretation of the Regulations to assist local authorities in discharging their duties as regulators in a consistent and compliant manner. However, these briefings are also made available for other stakeholders, including supply users, who may wish to understand how the Regulations apply to their specific circumstances. Technical briefings are also provided on private water supply management, water treatment, and advice which is aimed specifically at prospective buyers of premises served by a private water supply.
In Drinking Water 2023, the Inspectorate reported that it had revised its technical briefing on regulation 8, setting out the reasons why this was necessary. This followed consultation with legal professionals to clarify what did and did not constitute a regulation 8 private water supply in law.
The review that led to this revision identified several discrepancies and inconsistencies in the wider legislation in relation to regulation 8. In 2024, the Inspectorate raised these matters with Defra as they were causing increasing concern and confusion amongst various stakeholders, including the economic regulator and local authorities. For example, it became apparent that whilst the primary legislation makes it an offence to create or extend regulation 8 private water supplies, unless exempt under specific regulations, they must nevertheless be regulated as private supplies in accordance with regulation 8 where they exist. This at first seems counterintuitive. However, this is because the purpose of the Regulations at their inception in 2010 was firstly to facilitate a means to regulate onward distribution to protect consumers, but importantly and secondly, to seek them out to remediate their unlawful nature, and in so doing make them completely obsolete in time. Unfortunately, in the absence of any supporting mechanisms in place to achieve this, these secondary intentions were overlooked and have never been actioned or realised.
This review also identified that water resale supply arrangements, which are permitted under drinking water competition legislation, must be regulated as private supplies in accordance with regulation 8. Whilst the charging for onward distribution of water by a third party in this way is controlled by The Water Resale Order 2006, their creation or extension is nevertheless an offence under section 66(I) of The Water Industry Act 1991 (the Act). New Appointment and Variation (NAV) supply systems (Insets) also involve the resale and onward distribution of water from a water company’s supply system by a third party. However, they differ in that they are provided under licence by the economic regulator. This makes them public supplies, which are regulated by the Inspectorate. Any further distribution of a NAV’s system by someone other than the NAV, would however constitute a regulation 8 supply on its creation, and an offence under the Act.
Regulation 8 is itself difficult to apply in that it does not set clear criteria to determine where the further distribution of water by someone other than a water company is in scope and where it is not. Furthermore, the Regulations currently make no provision for local authorities to charge and recover some of the costs of their activities in association with regulation 8 supplies. These matters create confusion and frustration for stakeholders, leading to numerous enquiries and pleas to the Inspectorate to facilitate changes to the legislation, which it has no powers to do.
In 2024, as well as meeting with Defra colleagues to raise awareness of the apparent misalignment of legislation, the Inspectorate also presented at various stakeholder fora to explain the legislation and help provide some clarity. These included those made to The Chartered Institute of Environmental Health, Water Regs UK and several water company health liaison meetings.
In 2025, The Water Health Partnership in Wales initiated plans to develop guidance on the application of regulation 8. This intends to establish a consistency of approach between the local authorities and water companies in Wales. The Inspectorate is represented on this ‘task and finish’ group.
A significant amount of inspectors’ time is spent each year providing guidance on a case-by-case basis by responding to enquiries. These enquiries comprise both phone calls and email contacts. Unsurprisingly, the majority have been consistently from local authorities since the inception of the Regulations in 2010. The nature of these enquiries is variable, with some regulations attracting more enquiries than others.
In recent years, the Inspectorate has received several enquiries from local authorities requesting risk assessment training or seeking direction on where this is offered. These enquiries reflect a lack of training provision available in the sector. The Inspectorate is aware that at least one local authority may not be fulfilling its regulatory obligations due to not having sufficiently trained officers. Unfortunately, the Inspectorate is aware of only one training course that is made available to local authority officers in this key activity. The Inspectorate has had no sight of the content of this training and is therefore unable to comment on its suitability.
Some enquiries suggest a misconception of the role of the Inspectorate by local authorities with regard private water supplies. Although the Inspectorate offers technical advice on the application of the Regulations through its website and the enquiries line, it has no statutory duties beyond the collection of annual private water supplies data from local authorities, to provide an annual report on the quality of private water supplies in England and Wales, and to confirm (or not) any section 80 notice appeals that it receives. It has no remit to provide training or to facilitate improvements where they are needed, nor is it funded to do so. These are highlighted in the plethora of case studies that the Inspectorate publishes on its website. New case studies covering 2024 can be found on the Inspectorate’s website private water supplies case studies.
The Inspectorate is aware through enquiries that some local authorities are declining sampling requests from property owners or occupiers who are served by a private supply. The reason cited is that the ‘service’ is no longer offered. This would suggest either a misunderstanding of the regulatory requirements, or more worryingly that duties are knowingly not being fulfilled. It is of great concern that private supplies functions are knowingly being cut or closed when these functions are a statutory requirement. Unfortunately, the Inspectorate has no powers to investigate these reports, or those that are complaints about local authorities that have been unhelpful or have allegedly not met their regulatory obligations. Enquirers are reminded that each local authority has a complaints process which should be exhausted before contacting the Ombudsman | Public Services Ombudsman Wales. Local authorities are encouraged to consult the Inspectorate’s website prior to making an enquiry on private water supplies. In 2022 a new search facility specifically for private water supplies was created to assist those visiting the Inspectorate’s website site to locate the information and relevant guidance they seek www.dwi.gov.uk/private-water-supplies/guidance-documents/
Figure D Enquiries concerning private water supplies in England and Wales
