Written by Geoff Nemec (CIWEM, MSc, CENv) for prospective buyers of properties/homes on private water supplies this document is based on 20 years experience of dealing with Private Water Supplies in the UK.
Listed below are several questions that should be asked of the owner of the property through a solicitor or estate agent, or the local authority who regulate private water supplies. The aim is to establish water quality, the health risks, and the future cost liability.
a) What is a PWS
A private water supply is one which is not provided by a water company. About 1% of the population in England and Wales do not have a public supply of mains water to their home and instead rely on a private water supply. Mostly, but not exclusively, these occur in the more remote, rural parts of the country. The source of a private supply can be a well, borehole, spring, stream, river or lake and it can also involve storage structures or tanks. The supply may serve just a single property, or it can be much larger serving many properties and businesses through a network of pipes… Under rare circumstances you may be supplied with mains water by your water company but not receive a bill. In these circumstances you may be receiving a supply through a Private Distribution System. More information can be seen in the DWI technical note Information note on Regulation 8.
b) What does it mean to a homeowner
If the supply is to a single dwelling and is used only for domestic purposes, then the regulations do not require a risk assessment or sampling unless requested by the owner. It would be useful if the owner of the supply has had a risk assessment and monitoring carried out prior to purchasing a property to determine the wholesomeness and sufficiency of the supply. If the supply is shared between two or more properties, then the local authority is required to risk assess the supply and monitor it by sampling at an appropriate frequency. Risk assessment considers the source of the supply, the surrounding DWI Buyers Advice note _Version 4_15/04/2014 area, water storage tank and treatment, right through to the taps, to identify any actual or potential contamination.
NB: This involves a cost. You may wish to check whether there is any agreement among the other properties as to how these costs are shared or covered. This may also highlight that remedial action is required and again, you might wish to check how the costs for this would be met.
Q: Has a risk assessment already been carried out by the Local Authority, and if so when?
Q: Did the local authority advise that improvement works were required?
Q: What were the results of any previous sampling by the Local Authority?
Q: Did any results indicate a water quality problem?
c) Individual premises
Q: Is there any treatment within the property such as filters or UV disinfection units?
Q: Is the treatment appropriate (you could ask the current owner for evidence that the
system was fitted by a competent installer).
Q: Is the system compliant with Regulation 5 of the PWS regulations?
Q: Is the UV system validated for use on drinking water supplies?
Q: Has the current owner got any maintenance logs or records for the supply?
Q: Has the owner got any compliant spare parts for the supply, including any
Q: Have there been any problems with the supply such as taste and odour, discolouration or insufficiency.
Q: Are there any documented instructions detailing the procedures should any problems with the supply arise, e.g., sufficiency or water quality such as taste or odour issues. These should contain telephone numbers or other contact details to arrange for alternative supplies, pipe repairs, treatment system maintenance etc. DWI Buyers Advice note _Version 4_15/04/2014 Q: Is there a schematic of the supply showing the layout of pipes, tanks, inspection chambers etc. available?
Q: Is there a plan of the various parts of the treatment system, stating what each part is, for example, any filters, iron or manganese removal systems, and disinfection?