Introduction
A description of private supplies
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.
The locations of private supplies
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.
The Importance of regulating private supplies
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.
Quality of private supplies
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
The significance of sample results
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.
Improving water quality through risk assessment, risk management and enforcement
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.
Risk assessment and notices
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.
Fulfilment of statutory duties
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.