The independent Scottish Drinking Water Quality Regulator (DWQR) has published its annual report on public water supplies in Scotland for 2025 – reporting that drinking water quality in Scotland remains amongst the best in the world.

Introducing the report, David Reynolds, the DWQR, comments:

“Overall, drinking water quality remained very high, with 99.88% of samples taken from consumers’ taps complying with the required standards. This level of performance demonstrates that drinking water quality in Scotland remains amongst the best in the world and reflects the considerable efforts made by Scottish Water to deliver safe drinking water to communities across the country.”

Scottish Water takes and analyses its own samples to demonstrate compliance with regulatory requirements, with samples taken from drinking water as it leaves water treatment works (WTW), service reservoirs (SRs) or storage points and from randomly selected consumers’ taps.

DWQR independently assesses both Scottish Water’s monitoring programme and the resulting data.

In 2025, Scottish Water carried out a total of 296,935 regulatory tests; of these, 255 exceeded the prescribed standards. While overall compliance remained high at 99.91%, this represents a reduction from 99.94% in 2024 when 205 sample exceedances were recorded.

Of the 137,947 tests on samples taken to represent water supplied at the consumers tap, 99.88% complied with the standards. This reduction in performance was almost entirely due to a high number of exceedances of the standard for chlorate (45), highlighting the need for improvement in the storage and management of sodium hypochlorite at WTW.

"Many failures arise from more fundamental weaknesses in the management, maintenance and operation of drinking water supply systems"

David Reynolds also warns in the report:

“I do have concerns that Scottish Water have historically relied too heavily upon compliance figures to measure success.

“In last year’s report, I highlighted my concerns regarding the frequency of short-lived, yet largely avoidable, drinking water quality incidents and the occurrence of the discolouration of water supplies. Unfortunately, there has been little evidence of meaningful improvement during 2025….

“It is disappointing that the number of drinking water quality incidents investigated by DWQR increased further during the year, particularly as many were preventable…

“While ageing infrastructure and the impacts of climate change present significant challenges and contribute to some of the issues encountered, DWQR’ s investigations continue to show that many failures arise from more fundamental weaknesses in the management, maintenance and operation of drinking water supply systems.”

The Water Industry (Scotland) Act 2002 requires DWQR to publish an annual report describing the Regulator’s activities during the preceding year. The report summarises 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.

Scottish Water is required to notify DWQR of any event that may affect drinking water quality or lead to consumer concern. During 2025, Scottish Water reported 1,086 water quality events – the report points out that this is a significant increase from 866 events reported in 2024.

More serious events are classified as drinking water quality incidents. During 2025, DWQR investigated 36 incidents, two more than in 2024, continuing a concerning upward trend observed in recent years.

The report says DWQR remains particularly concerned by the number of preventable incidents caused or “exacerbated by Scottish Water's own actions (or inaction)”, including recurring failings in maintenance, chemical dosing and alarm response.

“Scottish Water CEO says "investment remains critical to strengthening Scotland’s water system”

Responding to the report, Alex Plant, Chief Executive of Scottish Water, said:

“We are delighted that the DWQR has reported that the quality of Scotland’s drinking water remains ‘world class – with more than 99.9% of tests meeting regulatory standards.

"We recognise that we can make improvements to our assets and processes to prevent things from going wrong. We seek to learn from every incident and are actively working to tackle the causes of water quality incidents.

“Many assets across our network are ageing and will require extra maintenance before eventually needing to be replaced. Most were not designed to cope with the type of weather conditions which are now the norm. This makes it ever more challenging to continue to improve drinking water quality.

“Investment remains critical to strengthening Scotland’s water system.”

The report says that DWQR will continue to work constructively with Scottish Water while maintaining robust and independent regulatory oversight to ensure that consumers continue to receive a safe, high-quality and reliable drinking water supply.

Click here to download the full report