Scotland’s Drinking Water Quality Regulator (DWQR) has published a report on the quality of water found in private water supplies. The report finds that many of these supplies comply with drinking water standards but a significant number need to make further improvements.

Around 3.6 per cent of the Scottish population receive their water from a private water supply rather than from Scottish Water. In 2017 local authorities reported to DWQR that there were 22,269 registered PWS in Scotland, 2,494 Type A and 19,775 Type B.

Environmental Health teams from local authorities review risk assessments and sample Type A PWS annually. In 2017, just over 93% of Type A supplies had either a completed or reviewed risk assessment. 

A total of 46,470 tests were carried out on samples taken from Type A PWS to check for a range of contaminants. In total, 95% of tests complied with the standards. The smaller Type B supplies fall outwith the prescribed monitoring regime but some are sampled at the request of users, grant applications or as part of public health investigations. Of those sampled, 13,432 tests were undertaken, of which just under 88% met the required standard. 

Of the samples taken from regulated supplies, E. coli was found in 11% of samples, indicating that they are not receiving the treatment necessary to make the water safe. Given the potential risks to public health, all failures are thoroughly investigated by the local authority.

In 2017, as in 2016, only one improvement notice was served by a local authority across the whole of Scotland, as local authorities work with users to secure improvements through discussion or the use of improvement grants. In view of the number of supplies failing to meet the drinking water quality standards over a prolonged period this is a surprisingly low number. Although responsibility for private supplies rests with owners and users, local authorities are urged to continue to provide appropriate advice and DWQR expects them to make full use of the enforcement powers available to tackle deliver improvements. It is expected that the new suite of enforcement options introduced by new Regulations for private supplies in 2017 will see an increase in formal enforcement action. 

Results confirm that, at a national level, the quality of Type A private water supplies is broadly constant and has not improved since 2010 in spite of ongoing efforts by local authorities and the availability of a Scottish Government-funded grant to encourage improvements. In addition to E.coli, other parameters with significant numbers of failures on private water supplies included coliforms, colour, hydrogen ion (pH), iron, manganese and lead. 

However, a considerable amount of work is being undertaken by local authorities and also through Scottish Government initiatives such as the VTEC/E. coli O157 Action Plan with the aim of reducing the risk to health for consumers and securing lasting improvements to the quality of private water supplies. 

The report from the DWQR is available here