Drinking Water 2025 – Private water supplies in Wales
Published 01:00:00 BST 7 July 2026
A private water supply is any water supply, not provided by a water company, where the water is intended for human consumption or for any food undertaking where the quality of the water may affect the final product. These supplies are regulated by the local authority.
3.27% of the population in Wales use a private water supply, although this is believed to be significantly under-reported due to the lack of mandatory registration and local authorities not meeting their statutory reporting duties. Most of these supplies are situated in remote, rural parts of the country and can originate from a range of sources including boreholes, natural springs, watercourses, and the onward distribution of mains water. The number of sites and population is included in Table 1. While the number of supplies has remained stable in the last few years, it is estimated that there are a further 41,764 supplies (Welsh Government, 2021) which are not registered with local authorities.
| Reporting year | Number of local authorities | Number of sites reported | Reported population |
|---|---|---|---|
| 2022 | 22 | 14,933 | 75,475 |
| 2023 | 22 | 14,786 | 64,220 |
| 2024 | 22 | 14,904 | 67,130 |
| 2025 | 22 | 14,902 | 104,431 |
A description of the types of private water supplies, as defined by Private Water Supplies (Wales) Regulations 2016 (as amended) (the Regulations) is provided here – Types of private supplies (Wales) – Drinking Water Inspectorate. Private water supplies serve a range of premises, both domestic and commercial, such as farms, bed and breakfast accommodation, holiday lets, hotels, sporting clubs, manufacturers, and other businesses. They contribute to the economy as well as the health and welfare of a known notable population of around 104,431. The population reported in 2025 is significantly higher than previous years, and analysis of this information would be required to determine the reason.
The standards and principles of regulation are the same for both public and private water supplies: to protect public health equitably regardless of the source of the water supply. The Regulations are underpinned by the principles of risk assessment and risk management to identify, manage and control risks to protect public health and sufficiency.
Private water supplies are found across most regions of Wales. The highest numbers are usually found in rural areas where connection to the public mains network may be difficult. Figure 1 shows the density of private water supplies across Wales.
In this 15th 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 water supplies in Wales relies on the provision of information and data by local authorities. The analysis of this information allows national reporting to direct policy change in pursuit of improving the quality of private water 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.
A significant amount of inspectors’ time is spent providing guidance on a case-by-case basis by responding to enquiries. These enquiries comprise both phone calls and email contacts. The majority of enquiries 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 on implementation than others.
The Inspectorate is aware, via enquiries from consumers, that some local authorities are declining sampling or risk assessment requests from property owners or occupiers who are served by a private water supply. These functions are a statutory requirement, therefore it is of great concern that local authorities are not fulfilling these duties which puts public health at risk.
The Inspectorate has no powers to investigate these reports, or 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 escalating to the Local Government and Social Care Ombudsman. The Inspectorate is aware that some consumers have initiated the Judicial review process, therefore this is also an available option where appropriate. It is also possible to write to your local MP and again the Inspectorate is aware of cases that have benefited from this approach.
Local authorities are encouraged to consult the Inspectorate’s website prior to making an enquiry on private water supplies. In 2022, a search facility specifically for private water supplies was created to assist those visiting the Inspectorate’s website to locate the information and relevant guidance they seek – The search page can be found using the following link Search – technical guidance notes.
During 2025, 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. Local authorities bear the sole obligation for reporting data and information to ministers under the requirements of regulation 16 and schedule 4 of the Regulations. Therefore, the Inspectorate will not accept data or information from third parties where no agreement is in place.
It is also a regulatory requirement for sampling and analysis to be accredited to ensure the integrity of the data.
Under the Regulations, drinking water should be ‘wholesome’ meaning it does not contain any microorganism, parasite, or substance at a concentration or value that exceeds limit values (in Part 1 of Schedule 1) or would constitute a potential danger to human health. In 2025, 3.62% (992 of 27,408) tests reported by the local authorities in Wales were found not to be meeting one or more of the standards for wholesomeness. Figure 3 shows that overall, there has been a reduction in tests failing the regulatory standards, although this improvement has plateaued in the last five years, indicating that the instances of identifying water quality risks, and remedying them has reduced. However, 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 water supplies recorded in Wales.
Escherichia coli (E. coli) and Enterococci are indicators of faecal contamination. The percentage of samples which were reported to be contaminated by E. coli and Enterococci, in the period 2015-2025, is shown in Figure 4 and expanded on in Table 3. From the samples reported in 2025, 7.10% of samples tested were found to contain E. coli and 5.56% contained Enterococci.
| Microbiological parameters | 2023 (%) | 2024 (%) | 2025 (%) |
|---|---|---|---|
| E. coli | 7.12 | 8.97 | 7.10 |
| Coliform bacteria | 13.62 | 12.52 | 11.58 |
| Enterococci | 7.73 | 7.39 | 5.98 |
| Clostridium perfringens | 4.98 | 5.25 | 4.03 |
These organisms are almost exclusively found in faeces, indicating a potential danger to the health of those drinking this water.
It must be noted that the testing regime is not uniform year on year with significant under-reporting. The number of consumers at private water supplies where E. coli and or Enterococci have been found equates to 147 supplies, indicating over 2,000 people drinking water at risk of faecal contamination. In comparison to public supplies which are 99.97% compliant with the water quality standards.
| Parameter name | 2023 | 2024 | 2025 |
|---|---|---|---|
| Aluminium | 1.68% | 1.82% | 1.33% |
| Colour | 1.86% | 2.29% | 1.03% |
| Iron | 3.19% | 4.02% | 2.73% |
| Lead | 3.93% | 2.80% | 3.48% |
| Manganese | 6.65% | 6.38% | 6.28% |
| Nickel | 5.16% | 5.78% | 1.49% |
| Nitrate | 0.95% | 0.86% | 0.50% |
| Odour | 0.52% | 1.82% | 1.81% |
| Taste | 3.92% | 1.43% | 0.58% |
| Turbidity | 1.51% | 2.19% | 1.24% |
Regular testing, annually, every five years or as informed by risk assessment, is essential to assess water quality and the effectiveness of control measures. 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 a supply’s regulatory testing regime to be determined and then met. This validation monitoring provides a baseline to measure the overall quality of the supply and the effectiveness of any mitigation measures. Other sampling, which could be called ‘investigatory’, can be recorded as such on the annual data return and is often undertaken following programmed sampling to investigate results which deviate from an established baseline, are near to, or exceed the standards.
For the reporting year 2025, a submission was received from 22 local authorities. Note that colony count test numbers have been removed from all years in this report’s charts.
In 2025, local authorities carried out 25,065 analyses of private water supplies samples. Figure 5 shows the number of samples taken since 2015, with 2020 representing an exceptional year due to the impact of the pandemic. There has been a gradual decline in the number of tests taken when compared to pre pandemic levels, increasing the sampling shortfall for private water supplies.
Due to the risks associated with private water supplies, increasing resources to reduce the shortfall would be beneficial to protecting public health.
Regulation 9 supplies are commercial or public use supplies and therefore are the types of supplies which pose the most potential for risk to public health. The expected sampling frequency based on the volume of water used for regulation 9 supplies for E. coli is stated in the Regulations. In 2025 of the samples analysed 76% met this requirement and 20% exceeded it, however, 4% were under-tested.
One of the key principles of 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.
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 – Risk Assessment tools and tips – Drinking Water Inspectorate.
Local authorities report information on risk assessments and enforcement action to ministers (in practice the Inspectorate) in two ways; in the annual data return, and through summaries of risk assessments. Also, throughout the year, local authorities must submit to minsters copies of notices served on supply owners for high-risk supplies or failing parameters. To date, the numbers stated in the annual data returns have never matched the number of documents received, with under-submission of risk assessment summaries and notices a consistent issue. Local authorities are reminded that documents can either be redacted or sent by a secure file transfer to preserve data privacy.
Table 5 highlights that local authorities are not making significant progress in moving towards 100% coverage of risk assessments. For the past three years, most private water supplies that should be risk assessed, either have never been, or were risk assessed more than five years ago. This demonstrates deficiencies in the regulatory governance of private supplies which were highlighted in the Inspectorate’s research project findings – Impact and future of the regulatory model and legislative framework surrounding private water supplies in England and Wales – Drinking Water Inspectorate.
| Supply type | In-date (within last 5 years) | Out-of-date (>5 years since completion) | No record of risk assessment | Total number of supplies | Risk assessments in date |
|---|---|---|---|---|---|
| Regulation 8 | 18 | 5 | 17 | 40 | 45% |
| Regulation 9 | 822 | 379 | 236 | 1437 | 57% |
| Regulation 10 (Shared) | 103 | 717 | – | 820 | 13% |
| Regulation 11 (Wales) | 469 | 631 | 241 | 1341 | 35% |
| Total | 1412 | 1732 | 494 | 3638 |
During 2025, in Wales more than one in 25 supplies in England are unfit for human consumption and pose a risk to health as they contain E.coli and Enterococci. 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. Protection of supplies from contamination is critical to protecting public health.
Should a supply be found to contain the presence of faecal indicators, the local authority is obligated to investigate in accordance with regulation 18 of the Regulations.
Lead was detected in 3.48% of tests. Lead is a neurotoxin that particularly affects children and can cause health effects in adults through long term accumulation 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 its refreshed technical brief on lead, which can be found on its website. The Inspectorate has published guidance on lead in private water supplies on its website – Lead in private water supplies – Drinking Water Inspectorate.
Nickel was detected 1.49% of tests. Nickel is largely detected because of nickel plated domestic fittings such as taps. Sometimes the source is not as 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 2.73%, 6.28% and 1.33% of tests respectively. All these metals can be found naturally occurring in source waters. Local authorities should consult with UKHSA to determine whether the concentration of these metals pose an immediate danger to health, and if so, must 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 1.24% and 1.03% 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 and fulvic substances in source waters. If these short-term occurrences become more frequent, this may be a result of long-term changes in weather patterns, and may indicate that additional treatment could be required in the future.
| Parameter | 2023 | 2024 | 2025 |
|---|---|---|---|
| Aluminium | 1.68% | 1.82% | 1.33% |
| Colour | 1.86% | 2.29% | 1.03% |
| Iron | 3.19% | 4.02% | 2.73% |
| Lead | 3.93% | 2.80% | 3.48% |
| Manganese | 6.65% | 6.38% | 6.28% |
| Nickel | 5.16% | 5.78% | 1.49% |
| Nitrate | 0.95% | 0.86% | 0.50% |
| Odour | 0.52% | 1.82% | 1.81% |
| Taste | 3.92% | 1.43% | 0.58% |
| Turbidity | 1.51% | 2.19% | 1.24% |
The data return suggests that just four supplies have an in-date risk assessment for PFAS. This is four more than in 2024. In total, 10 tests for Perfluorooctanoic acid were undertaken and all results passed. Local authorities are encouraged to refer to the Inspectorate’s guidance on PFAS, which was updated in 2025 – PFAS Guidance.
The Inspectorate encourages local authorities to submit PFAS data in annual data submissions. PFAS samples will be regarded as ‘investigatory’ samples as tests are not required under schedules to the Regulations.
The Inspectorate has published guidance on PFAS in private water supplies on its website – Poly and Perfluorinated Alkyl Substances (PFAS) – Drinking Water Inspectorate.
In 2025, the Inspectorate published research on efficacy studies of PFAS removal which may be of benefit to local authorities and relevant persons – Bench-Scale and Pilot-Scale Water Treatment Efficacy Studies of PFAS Removal – Drinking Water Inspectorate.
Local authorities are required to serve 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 (the Act) where supplies are unwholesome and or insufficient.
Most notices are served in response to a failure of a microbiological standard, with a small minority for failures of other standards. In 2025, according to the data return, 230 out of the 319 notices served were for failures of microbiological standards. 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 are obligated to notify the Inspectorate and provide a copy of notices served. In 2025 the Inspectorate was notified of 96 notices being issued, all but one of these was a regulation 20 notice with the other being a section 80 notice. This discrepancy between notices reported to the Inspectorate and recorded in the data return demonstrates underreporting and local authorities not complying with their statutory duties to report.
Local authorities still appear to be predominantly reacting to sample results, rather than proactively eliminating the problems that could result in a test failure. The use of a proactive risk assessment, and if necessary, a notice in this context, is to protect users before unwholesome or unsafe drinking water occurs.
| Failed parameter name | Notices served |
|---|---|
| E. coli | 72 |
| Coliform bacteria | 71 |
| Enterococci | 68 |
| Clostridium perfringens | 19 |
| Hydrogen ion (pH) – indicator – zone | 18 |
| Lead | 15 |
| Colony counts after 3 days at 22°C | 10 |
| Manganese (total) | 10 |
| Colony counts after 48 hours at 37°C | 7 |
| Iron (total) | 6 |
| Aluminium (total) | 5 |
| Turbidity | 5 |
| Colour | 4 |
| Copper (total) | 4 |
| Nickel (total) | 2 |
| Arsenic (total) | 1 |
| Hydrogen ion (pH) (indicator) | 1 |
| Nitrite – consumers taps | 1 |
| Total | 319 |
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 eight case studies compiled in 2025. These can be found on the website at Drinking Water Inspectorate (dwi.gov.uk):