Unions are meeting with Irish Water at the Workplace Relations Commission today over plans to separate the utility from its parent company Ervia.
Last week, the Cabinet agreed on a plan which would see Irish Water becoming a single national utility by 2023.
Thousands of staff are expected to be transferred from local authorities to Irish Water as it assumes direct responsibility for the provision of water services.
The national secretary of the public service union Fórsa said that his union has grave concerns about the plan.
Speaking on the way into the talks this morning, Peter Nolan said: "We are here to set out trenchantly our concerns in relation to the proposals to establish a single public service entity".
He continued "put simply we haven't come across any member who favours this proposal and we're going to be telling the WRC that".
SIPTU's Adrian Kane said a referendum is needed to ensure that water remains with the public sphere.
He said: "We need for the existing guarantees that we have for local authority workers, these service level agreements, that they remain in place and are honoured in full".
Mr Kane said SIPTU represents 3,000 employees who work for local authority services and provide water services for people at the moment along with Irish Water.
He said: "Our understanding of the process is that the WRC will make a submission to the Minister after it’s heard the various parties".