Page last updated at 13:09 GMT, Thursday, 27 November 2008
Hundreds of employees at Scottish Water have started a 24-hour strike over wages.
The firm said the action involved 802 union members and it had contingency plans in place to maintain services.
The unions involved are Unison - which said more than 1,000 staff were taking action - Unite and the GMB.
It is the latest in a series of separate pay disputes affecting thousands of workers in Scotland, including bus drivers and coastguards.
Scottish Water said the pay award it had made was within public sector guidelines. It was paid in the September salaries of the company's 3,685 employees and was backdated to April. The award equates to 3% over 15 months.
But Unison said Scottish Water could afford more.
Dave Watson, the union's Scottish organiser, said: "In recent years our members have helped to save Scottish Water over £1bn through reduced operating costs and improved efficiencies.
"Customers and directors have benefited, while workers have faced real terms pay cuts due to inflation."
Peter Farrer, Scottish Water's customer service delivery director, was confident usual services could be maintained during the action, which will finish at midday on Friday.
He said: "We have a committed team in place, determined to maintain a normal service for our customers."
Director of communications Chris Wallace added: "We are deeply disappointed; this decision is not the right action for Scottish Water."