The study published by the Scottish Executive said the country's waste water rate was running at 45%.

A spokeswoman said the figures were "a reflection on the poor state of Scotland's water mains".

What we are left with is a network which suffered from a long time of underinvestment Scottish Water spokeswoman

The water supply report for 2000/01 said that Scottish homes and businesses used an average of 2.41bn litres of water every day.

However, 1.01bn litres are lost before supplies reach customers.

The highest leakage rate was found in the west of Scotland, where 630m litres of water were lost every day.

That equated to 53% of the total supply used in the area.

In the north of Scotland 165m litres were lost in an average day, representing 38% of the total supply.

Underinvestment

Scottish Water said it was spending £1.8bn on a programme to improve all its services.

A spokeswoman said many pipelines still dated back to the 19th century.

"There is leakages and there is water going out and what we are left with is a network which suffered from a long time of underinvestment," she said.

"We are currently making an assessment across Scotland of our water mains.

Mains renewal

"We are fitting meters into the network and from those we can read the pressure levels and get a very strong picture of where leaks take place."

A spokeswoman for the Scottish Executive said: "An extensive mains renewal programme is under way.

"Prioritisation within the programme is based on a range of factors such as water quality, hydraulic performance, leakage, burst records, etc.

"Where new water treatment is planned the distribution mains are checked and all significant leaks are repaired before the works is commissioned."