While in 2004 only 0.88% of tap water samples contained coliforms – a group of bacteria that includes e-coli – in 2005 this percentage rose to 0.97%. This corresponds to 138 failures of the coliform standard in 2005 compared to 123 failures in 2004.

Although not all coliforms pose a health risk, they are an important indicator of water quality, as high coliform concentrations indicate that more serious pathogens such as salmonella could be present.

Colin McLaren, head of the Drinking Water Regulator (DWQR) for Scotland, said he was ‘concerned’ about coliform concentrations in Scotland’s water supply.

Twenty-five of last year’s 42 water quality incidents investigated by the DWQR involved bacterial pollution, he said – a rise in the total number of incidents from 28 the previous year. The DWQR will be taking the matter up with Scottish Water to make sure the previous positive trend is not reversed for good, he said.

Water companies should reduce disinfection failures by improving equipment maintenance and operating procedures, and respond quickly when failures do occur to prevent polluted water reaching customers’ taps, the watchdog said.

But overall Scottish tap water quality improved since 2004 as the rise bacterial pollution was offset by improvements in colour, pH and thihalomethane concentrations.

The report found that 99.56% of tap water samples taken in Scotland fell within UK and European norms in 2005 – an improvement on 99.42% in 2004.

Scottish Water’s chief scientist, Richard Allan, said that the report “confirms the long term improvement in the quality of tap water across the country in our continued drive to protect public health.” The company will be investing £500m in water treatment works and operational solutions over the next four years, he said.

Scottish tap water quality compares unfavourably with England and Wales, where as much as 99.96% of drinking water samples were within regulatory norms in 2005, however (see related story).

The Scottish Conservative party responded to the report by calling for the privatisation of Scottish Water.

Scottish Conservative environment spokesman Alec Johnstone said: “Scotland’s water consumers are getting the worst of all worlds. Water that is below the standards recorded in England with an infrastructure that is creaking at the seams and acting as a brake on some much needed developments, both residential and industrial.

“If Scottish Water is to deliver the safe, high-quality service that the public deserves, and if it is to attract the investment needed, then it must be taken out of state control.”

Goska Romanowicz

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