Private water supplies in Wales: information to support public health priorities

Private water supplies (PWS) are used by a significant proportion of households in some British regions. Chemical and physical factors both have the potential to impact upon the well-being of PWS users.

The chemical quality of PWS can vary greatly, dependent on the composition of the surface or groundwater from which they are drawn, and the infrastructure and treatment of the water supply. Recent Public Health England/NERC-BGS research has shown that PWS users often do not treat to improve chemical quality, or do not maintain their treatment systems. PWS tap water quality cannot be assumed to be improved from its natural state, and may be significantly worse than drinking water standards. It is important stakeholders across all scales (household, local and national) better understand the distribution of factors which influence water quality.

We have established that current efforts to assess national and regional water quality priorities in Wales are hindered by a two-way knowledge barrier. Stakeholders are unaware of the large NERC data resource which could be used in their assessments, whilst NERC data holders do not have sufficient understanding of stakeholders' needs, and how the data can be most usefully presented and disseminated. Barriers to direct uptake of this NERC data include: the current format (hard-copy or digital documents); chemical element mapping formats (which may divide the concentration range into arbitrary intervals and not show thresholds of relevance to users); bespoke indices using more than one variable are needed (e.g. plumbosolvency); and, resource pressures on public body officers (e.g. time, expertise, computing, GIS).

A further problem exists which NERC data can contribute to resolving. Assembling the evidence base to determine what, if any, action should be undertaken at national or regional scales is compromised by the lack of systematic registration, in any database, of the most prevalent type of PWS, i.e. "Single Domestic Dwellings" (SDDW). SDDW users are not compelled to register their supply with the Local Authority, and in Wales, 85% of registered PWS are SDDWs. There is widespread awareness, at all levels of governance, that there are considerably more than the officially recorded 12,242 SDDWs. Improved estimates of the locations of these properties, can help national and local government assess, and prioritise, risks arising from geospatially controlled factors (e.g. high metal concentration and vulnerability to drought). Recent NERC-funded research has built a spatially resolved, predictive model of the likely occurrence of PWS in Wales. In order to fulfil its potential impact, this work now needs to be shared with the key stakeholders at regional and national level. Specific examples will be developed that indicate regions where large numbers of PWS users coincide with expected high risks of events (e.g. flooding, drought) under future weather scenarios, and allow an improved understanding of pressures on marginal aquifers.

Sustained inter-organisational and inter-personal communication will ensure the successful progress of this project. At an overarching level this will be achieved through active participation in an existing national forum, the Water Health Partnership, and by undertaking short-term secondments into key Local Authority and public body offices (Public Health Wales, Dwr Cymru Welsh Water, Natural Resources Wales, Powys County Council). Outward facing communication, of agreed key messages, is embedded into later activities. Web, mobile and selected more traditional mechanisms will be used to ensure that outreach is as equitable and widespread across private water supply users as possible. Project reports will be available in both English and Welsh.

KEYWORDS: private water supply; lead; drought; flooding; manganese; public health.

The primary project outcome will be an improved understanding of environmental risks to private water supply users in Wales. The outputs will greatly increase the evidence available to local and national authorities on where threats to health and well-being may lie, and whether these warrant action at the national or local level. The project partners on this proposal include all the stakeholders who are responsible for those decisions, and their full participation has been ensured by their active contribution to the project design. This project will support greater effectiveness in public services, at a time when public bodies are increasingly under pressure to make efficiency savings, and the outcomes will enhance quality of life through influencing public body policy and individual (householder) action.

The project partner (Public Health Wales (PHW), Public Health England (PHE) Centre for Radiation, Chemicals and Environmental Hazards, Wales (CRCE-W), Water Health Partnership (WHP), Dwr Cymru Welsh Water (DCWW), Natural Resources Wales (NRW), Powys County Council) involvement in planning represents an early increased impact for NERC, through better stakeholder understanding of the data and knowledge resources, which will continue during the project.

Measureable impact will be realised through the delivery of mapping outputs to project partners. Improved national understanding of the spatial distribution of physical risks (e.g. drought, flooding) are of interest to PHW, CRCE-W and NRW, in their roles to protect human health and environmental resources. PHW and CRCE-W will also benefit from an improved understanding of the expected location of private water supply users and refining that to assess whether there are threats to specific vulnerable groups. Mapping the spatial distribution of chemical properties of water will benefit all WHP members, but particularly PHW and CRCE-W, to assess the scale of likely threats. These will be considered in the context of public health concerns, and form the basis for further action by those bodies. Local authorities will benefit from increased appreciation of NERC data, and how it may help them understand their local environment, and the risks to householders with private water supplies: all 22 are part of the WHP, and we will visit the largest, Powys, during this project.

Householders using, or considering using, private water supplies will benefit from the increased availability of information on important generic and local considerations, particularly those relating to chemical quality: this will lead to better informed decision making, and improved health, where householders choose to follow the advice. We will help to close an important knowledge gap (exposure to high levels of chemicals is demonstrably occurring), through reinforcing messages of the importance of monitoring and appropriate treatment of drinking water. Longevity of impact is also expected from the long-term availability of the bilingual resources online, free-of-charge.

The PHE project partner invitation to the Environmental Public Health Tracking meetings (EPHT), to speak about this project, and newsletter space, will allow us to directly reach other stakeholders. EPHT includes public health representatives from across the UK, the Chartered Institute of Environmental Health, Local Government Association and Drinking Water Inspectorate (DWI). DWI are the regulator for public water supplies, although not for private water supplies. However, DWI do compile Local Authority private water supply summary statistics each year: the EPHT meeting will allow us to update DWI on project activities and outcomes.

NERC staff development will be considerable, e.g. better understanding of priorities in the protection of health from environmental challenges, an increased realisation of how different public sector bodies use data, and what constraints they face. We anticipate ongoing WHP interactions post-funding.