Capacity problems at sewage treatment plants may stop new housing developments being built in many parts of Northern Ireland, the construction sector has warned.
NI Water needs extra money to address the problem, the Construction Employers Federation has said.
The federation represents builders in Northern Ireland.
It said that a recent government study found up to £750m may be required to tackle the capacity issue.
The federation will meet the head of the Northern Ireland Civil Service, David Sterling, on 8 February to ask that the 2019-20 budget takes the problem into account.
There are capacity issues at more than 70 treatment works, with NI Water advising no new homes can be connected to the waste water network in affected areas.
Larne, Saintfield, Lurgan, Dungannon and Limavady are among the places affected.
The situation means developers would have to fund their own private sewage treatment works if they wanted projects to proceed.
Costs would then likely be added to property prices, making them harder to sell.
The federation has written to Mr Sterling, stating "a further deterioration" of the problem will "halt development across large swathes of Northern Ireland".