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19 September 2017

Drinking water quality - public and private supplies

The Drinking Water Quality Regulator for Scotland (DWQR) published her 2016 annual reports on public and private supplies on 7 September.

These reports (available at http://dwqr.scot/information/annual-report/) summarise data on water quality in public and private supplies across Scotland, as well as covering water quality events and incidents, consumer contacts to Scottish Water and DWQR activities throughout the year.

Compliance with the standards set out for public supplies in our legislation and in the EU Drinking Water Directive in 2016 was 99.91%, demonstrating the continuing high quality of drinking water that consumers in Scotland receive. During 2016, 26 drinking water quality incidents occurred which required detailed investigation, fewer than the 35 incidents which occurred during 2015. Incidents occur for a variety of reasons, though some common themes were evident during 2016, including failure of equipment, lack of monitoring and in some cases human error. There is still considerable scope for Scottish Water to reduce the numbers of drinking water quality incidents through improved maintenance and monitoring of water treatment processes and ensuring that lessons learnt are shared across operating areas.

During 2016, the DWQR submitted a report to the Procurator Fiscal following its investigations into a drinking water quality incident from 2015, when over 6,000 properties in North Lanarkshire suffered restrictions on the use of their water following contamination of the supply.

The sources of private water supplies (PWS) are many and varied, and a large number of householders and businesses depend on them for their drinking water supplies. In 2016, local authorities reported to DWQR that there were 22,118 registered PWS in Scotland, 2,458 Type A and 19,660 Type B. Type A supplies are those which supply 50 or more people or 10m3 water or more, and any PWS which is used in a commercial or public activity. The Type B classification relates to smaller, domestic supplies. Around 3.6% of Scotland’s population rely on PWS for their drinking water, but a significant number of others, for example visitors and tourists, will also consume these supplies.

Environmental Health teams from local authorities annually review risk assessments and sample larger Type A PWS. In 2016, 93% of Type A PWS had either a completed or reviewed risk assessment, with 16 local authorities reporting that they had reviewed risk assessments for all of their Type A supplies. A total of 47,737 tests were carried out on samples taken from Type A PWS, with 94% of tests complying 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, 13,472 tests were undertaken, of which 87% met the required standard.

The DWQR considers that the data presented in the PWS report do not indicate significant improvements in the quality of private water supplies, but highlighted the considerable work being undertaken by local authorities and also through initiatives such as the Private Water Supplies Improvement Strategy and the VTEC/E. coli O157 Action Plan. These initiatives aim to secure lasting improvements not only to the quality of private water supplies but also to reduce the risk to health.

Vol: 51 No: 37 Year: 2017 Page:

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