Most people who move house inherit a water company as their supplier. A minority of homes in rural parts of England and Wales are instead connected to a private water supply: a borehole, spring, stream or a shared pipe from a neighbouring source. The Drinking Water Inspectorate (DWI) says about 1% of the population of England and 3% of the population in Wales use one. Buyers and tenants who arrive without knowing this can find they have taken on responsibilities that a mains customer never faces. This article summarises DWI guidance, which covers England and Wales only. It is general information, not legal advice.
What counts as a private supply
The DWI defines a private water supply as any supply not provided by a water company, where the water is intended for human consumption or for a food business. Human consumption covers drinking, cooking, food preparation and other domestic purposes, including toilet flushing. Sources include boreholes, natural springs, watercourses and the onward distribution of mains water. Local authorities, rather than the DWI, regulate private supplies, with the Inspectorate acting as technical adviser to them.
Becoming the “relevant person”
Section 80(7) of the Water Industry Act 1991 defines the “relevant person” as the owner or occupier of the premises supplied, the owner or occupier of the premises where the source is situated, and anyone who exercises powers of management or control over the source. There can be several relevant persons for one supply. The DWI’s buyer guidance says that once a property with a private supply is purchased, the new owner becomes a relevant person. A tenant, as an occupier, can also fall within the definition.
The status matters because, if the local authority finds a supply insufficient or unwholesome, a relevant person may be served a notice under section 80 requiring improvements. Where a supply is a potential danger to human health, a notice can be served under regulation 18 in England (regulation 20 in Wales). The DWI says failing to comply with such a notice is an offence carrying a fine, or a term of imprisonment not exceeding two years, or both.
Questions a buyer can put to the seller
The DWI suggests buyers check the property deeds for binding agreements about who controls and maintains the supply, and take legal advice on liability. It also lists questions to put through a solicitor or agent, or to the local authority, including:
- Are there written or informal agreements on maintaining and operating the supply?
- Has the local authority carried out a risk assessment, and what did it find?
- Were improvement works advised, and have they been completed?
- What did any previous sampling show?
- Is there treatment such as filters or UV disinfection, and was it installed by a competent installer?
- Are there maintenance logs, emergency instructions, and a diagram showing pipes, tanks and inspection chambers?
Testing and risk assessments for a single home
The DWI says most private supplies in England and Wales serve a single dwelling. Regulations do not require mandatory monitoring or a risk assessment for a supply serving only a single home used solely for domestic purposes, unless the owner or occupier, including a tenant, asks the local authority. If testing is requested, the minimum parameters normally include conductivity, enterococci, E. coli, pH and turbidity. Both testing and risk assessment are chargeable, and the DWI notes water quality can vary with seasonal changes in the source, so a single result does not necessarily represent water quality at other times.
A home used commercially, such as a bed and breakfast or tea shop, falls outside the single-dwelling category, and different rules apply.
Registration and the local authority
The DWI says registering a private supply is not currently a legal requirement, though it strongly advises it. Anyone can make the local authority aware of a supply, and a consumer unsure whether the supply is known to the council can ask its environmental health team. When the authority becomes aware of a new supply, the supply must not be brought into use until the authority is satisfied it is not a potential danger to human health.
Practical points for a move
- Ask early whether the property has mains or private water, since a removal firm cannot resolve a source or pipe dispute on moving day.
- Check who owns and maintains shared pipework before exchange, as deeds may contain obligations.
- Keep records of any maintenance the seller has done, because the DWI stresses record keeping.
- Do not assume a tenant has no role: an occupier can be a relevant person.
- For homes on mains water, the site’s guide to moving home and your water bill covers meter readings and billing.
Common questions
Does the local authority have to test my private supply?
Not for a single home used only for domestic purposes, unless the owner or occupier asks. Other supplies are risk-assessed as part of the authority’s duties.
Can the council charge for this?
Yes. The DWI says authorities can charge relevant persons the reasonable cost of the work, and Welsh regulations set maximum fees for each service.
Is a private supply always unsafe?
No. The DWI points out that quality depends on the source, the treatment and how the supply is maintained, which is why risk assessment is recommended.
The bottom line
A private water supply in England or Wales shifts responsibility for quality, sufficiency and maintenance from a water company to the property owner or occupier. Before committing to a purchase or tenancy, check the deeds, ask the DWI-suggested questions about risk assessments, sampling and treatment, and consider requesting a local authority risk assessment.
Sources
- Drinking Water Inspectorate, “Buying a dwelling with a private water supply: what do I need to know?”
- Drinking Water Inspectorate, “Relevant person”
- Drinking Water Inspectorate, “Single dwelling supplies”
- Drinking Water Inspectorate, “Registration of private water supplies”
- Drinking Water Inspectorate, “What are private supplies?”