The State would face immediate costs of up to €160m if Irish Water was scrapped, according to the minister in charge.
Simon Coveney has said the costs would be rung up from having to let go of staff who transferred from local authorities.
But he has also told the Dáil the cost could rise into the billions, as potential savings would be lost in future.
Minister Coveney has said the costs were calculated as part of Fine Gael's pre-government talks with Fianna Fáil: “It was estimated that once off costs for staff redundancies, termination of contracts, transitioning to another model etc, could range between €85m and €169m.
“In addition some €1.6bn additional running and capital costs will arise from the period of the Irish Water Business plan to 2021.”