Hundreds of workers at Scottish Water will take 48 days of strike action over three months which could see disruption to repairs and delays in responding to floods, unions have warned.

Unite the Union, Unison and GMB Scotland have confirmed more than 500 of their members at the organisation will take action over a pay and grading dispute.

They claim managers linked this year’s pay offer to a wider restructuring of grades and salaries, which the unions believe will limit the future wages of workers and must be negotiated separately.

Strike action will begin at midnight on November 10 and last until 23.59pm on November 13, and this will be repeated weekly until January 26.

The unions said the strike action is likely to cause disruption and significantly impair Scottish Water’s ability to respond to leakages, flooding, pollution, and drinking water quality concerns.

In practical terms, this means burst pipe repairs on roads and highways will not be repaired by Unite members on the scheduled days of action.

Unite members will also not be available to undertake work relating to any sewer flooding issues and the associated environmental impact of failing sewage works.

Stephen Deans, Unite regional co-ordinating officer, said: “Scottish Water has paid lip service to our major concerns over pay which is being tied to a proposed new grading structure.

“The talks which have taken place with Scottish Water management following our membership emphatically backing strike have been in effect useless.

“Unite has therefore been left with no option but to serve notice of 48 days’ strike action over three months.

“Unite’s membership includes key frontline workers who attend to and repair waterworks, flooding and sewers. If the action goes ahead due to the intransigence of Scottish Water management, then this will have major public safety and health implications.”

Unison’s Scottish Water branch secretary Patricia McArthur said the firm’s treatment of workers is “storing up problems for the future”.

GMB Scotland organiser Claire Greer has urged the First Minister to intervene to avert strike action, saying there has been no genuine attempt by Scottish Water to resolve the dispute, while Unison has written to Government minister Mairi McAllan.

Unite general secretary Sharon Graham said Scottish Water had created the situation “through their own arrogance and insatiable greed”, as she vowed the union will “fully support” members.

The publicly-owned company said it is putting in place a contingency plan for strike days and is examining how its activities may be impacted.

Chief operating officer Peter Farrer said the firm will do all it can to ensure customers do not experience disruption.

Mr Farrer added: “We are dismayed the unions have taken this course of action over what is an exceptional proposal for our people.

“Scottish Water remains committed to reaching an agreement with our unions that avoids industrial action.

“This has been the case throughout the negotiations over the proposal to modernise a 21-year-old pay and grading structure and provide employees with an in-year award of at least 8% for all.”

A Scottish Government spokesperson said: “These pay negotiations are a matter for Scottish Water, as the employer, and the unions – we encourage all parties to continue negotiations to resolve this dispute.”