Members of the four unions voted for industrial action

The move comes after members of the four unions voted for industrial action. They say attempts to engage the government in negotiations have failed.

The umbrella group for the unions said the industrial action will start with a one-day strike then work to rule.

Plans for a government company to take over from the existing Water Service could see up to 700 jobs lost.

'Emergency provisions'

Bumper Graham, Secretary to the Water Service Trade Unions, said consumers would not be affected by the strike.

"Our aim is not to in any way damage provision of services, and hopefully the public will see no adverse impact," he said.

"We are going to ensure emergency provisions are put in place, and the unions will guarantee there will be continuous supply during the dispute.

"This action is not aimed at the public - it is aimed at the minister and senior civil servants."

Minister John Spellar said he regretted the decision but said he respected their rights to pursue lawful strike action.

"I would urge the trade unions not to use the issue of water charging to prevent the necessary improvements to the workings of the Water Service," he said.