Industrial action by staff at NI Water could cause some disruption to water supplies over the Christmas period.
Talks aimed at resolving an ongoing dispute over the government-owned company’s pension scheme ended without agreement.
More than 1000 workers will be involved in the industrial action from Monday onwards after more than 90 per cent backed a ballot organised by the Water Group of trade unions.
It will involve a work to rule, including a withdrawal of on-call, standby and overtime working at more than 2,7000 treatment works and pumping stations.
The unions claim the current pension scheme is to be scrapped, meaning many staff members will see their contributions increase by £100 per month.
Union representatives met DRD minister Danny Kennedy on Wednesday but they unanimously rejected what they described as “minor concessions” tabled by NI Water management.
NIPSA assistant secretary Ryan McKinney, who has been involved in the negotiations, said: “The unions have set out their position to both the minister and NIW and unless the pension proposals are taken off the table staff will take action from Monday.”
Mr McKinney added: “The trade unions are willing to continue with negotiations right up to and beyond December 22 in order to attempt to find a solution and avoid disruption to communities.”
In a statement earlier this week, NI Water said it regretted that the action was being taken at this time.
A spokesman said: “NI Water remains committed to trying to resolve the issues at hand and continues to offer ongoing engagement with trade union colleagues.”