Unions have warned Irish Water and local authorities that there will be industrial action if the current Service Level Agreement regarding job security for members is not observed.
SIPTU organiser Brendan O'Brien said their position was that any breach would precipitate a dispute.
Management and unions met this afternoon to discuss staffing issues.
Last week SIPTU and the TEEU voted overwhelmingly in favour of industrial action after Irish Water earlier revealed plans to cut 1,500 jobs by 2021.
The result of Unite's ballot is due on Monday, while IMPACT will deliver its outcome on 11 December.
Further meetings are scheduled between the two sides.
When Irish Water was established, a Service Level Agreement was drawn up with local authorities, whose staff were to operate the water service on behalf of the new utility.
However, last month Irish Water announced that it would be seeking up to 1,500 job cuts by 2021 in a bid to secure 1.1 billion in savings from a cost base reduction of 7% a year.
Irish Water notes that this target was imposed by the regulator - and that 356 jobs have already been reduced without dispute.
It denies it has breached any agreement.
However, unions argue this move is a breach of the original Service Level Agreement, and that the public water service cannot be adequately delivered if the job cuts which they estimate at 40% of the workforce are implemented.
They fear that this would open the door for jobs to be outsourced and ultimately lead to the "creeping privatisation" of the water utility.
Last week, a spokesperson for the Department of Environment, Community and Local Government stressed that privatisation of Irish Water was not on the agenda, and the Government was firmly opposed to it.
Irish Water would not be able to implement redundancies itself as the workers in question are actually direct employees of local authorities.
SIPTU members backed industrial action by 91%, with 84% of TEEU members supporting it.
Around 4,000 workers are employed in water services - with the vast majority represented by SIPTU, the TEEU, IMPACT and Unite.
