The report said drinking water quality had improved

An investigation by the Drinking Water Quality Regulator for Scotland (DWQR) found that 99.56% of tap samples met European standards.

But thousands of consumers complained to Scottish Water about the colour and taste of their household water.

The 2005 study looked at more than 150,000 tap samples across Scotland.

The report found a 0.14% improvement in quality compared with the previous year.

Overall, Scotland has good, safe, high quality drinking water Colin McLaren Drinking water regulator

Commenting on the findings, water regulator Colin McLaren said: "Overall, Scotland has good, safe, high quality drinking water and I am pleased to report that in 2005 Scottish Water continued to build on improvements made in 2004.

"However, consumer expectations are also high and many of the complaints received by Scottish Water are about the aesthetic quality of the water flowing from our taps.

"Of the 22,500 drinking water quality complaints received by Scottish Water last year, 86% related to the appearance of the water."

Deputy Environment Minister Rhona Brankin echoed the independent regulator's call for Scottish Water, a public company, to make water look and taste better.

She said: "It is important to customers that the product they are receiving also looks good enough to drink."

Sample failures

The DWQR report found a slight increase in the levels of bacteria in tap samples.

Some 138 tap samples failed a test for coliform, a type of bacteria, compared to 123 in 2004.

The number of faecal coliform (E.coli) failures also increased slightly from 18 to 21, a trend described in the report as "disappointing".

The study recorded 25 incidents involving microbiological sample failures or failures of the disinfection process during treatment.

Scotland's water consumers are getting the worst of all worlds Alec Johnstone Scottish Conservative environment spokesman

The Scottish Conservatives said the report was evidence that consumers were getting a bad deal in comparison to England and Wales, where the water quality had been proven to be slightly higher.

Environment spokesman Alec Johnstone called for Scottish Water to be taken out of state control.

He 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."

The DWQR looked at a total of 345,761 samples last year, taken from water treatment works, service reservoirs and consumer taps.

Upgrading water supplies

The largest number of complaints received by Scottish Water came from the south west of the country, incorporating Glasgow and Stirling.

The problems reported included metallic and earthy-tasting water and water with a cloudy, orange or black appearance.

Scottish Water said more than £500m would be spent upgrading water supplies over the next four years.