WATER and sewerage infrastructure in Northern Ireland is set to "burst at the seams" without billions of pounds in additional funding, NI Water has warned.
The publicly owned company in charge of the north's water supply urged Stormont chiefs to develop options on "sustainable financing solutions".
Dr Len O'Hagan, chair of NI Water, said a further £2.5 billion is needed to "remain fit for purpose".
He said that "operationally, NI Water has never been in better shape" and the firm has "delivered while keeping bills affordable".
"However, we are facing a tipping point, we need to start making decisions now if we want to maintain water services that one would expect in a healthy, western European economy," he said.
Dr O'Hagan said underfunding "has already resulted in curbs to economic development", and warned that there are "currently 99 areas where new housing and businesses may be unable to get connected to our sewerage system".
"Indeed, the growth of Belfast city, the primary economic engine of Northern Ireland, will struggle unless the £1bn investment in strategic drainage, under the Living with Water Programme, is supported. The City Deal risks not realising its full potential. Put bluntly, no drains means no cranes," he said.
"However, there is a window of opportunity to invest properly in our water and sewerage infrastructure. To remain fit for purpose, we calculate that the sum is £2.5bn, including £1bn to address used water, flooding and drainage problems in Belfast alone.
"Funding at this level will not solve all of the issues, but it will allow us to address 70 per cent of our used water capacity problems whilst protecting drinking water and enhancing environmental protection."
Dr O'Hagan urged Stormont's departments for infrastructure and finance to develop sustainable financing options by engaging with industry experts.
"Over the years, we have learnt to do more for less and have achieved some amazing results," he said.
"As chairman of NI Water, my appeal is direct but simple: Give us the funding and let us show you what we can achieve to help deliver a healthy and thriving population, a growing economy and a flourishing natural environment."
Dr O'Hagan was speaking as NI Water launched its annual report for 2018/19 and its draft strategy 2021 to 2046.
In Northern Ireland, water charges currently only apply to non-domestic properties.
As Secretary of State, Peter Hain had threatened to introduce household water charges under direct rule in 2007, but the move was scrapped after Stormont's parties agreed to restore a power-sharing devolved government.
An independent review in 2007 said householders already paid an average of £160 annually towards water and sewerage services through their rates bills.
