Persistent underfunding of NI Water has led to a shortfall in the wastewater infrastructure, which in turn, is limiting house building and other development.
The Fiscal Council has produced a report concluding that NI Water’s current funding model is not fit for purpose.
Prof Barrett suggested the Stormont Executive could look outside the UK and Ireland for a better funding model.
He said that on the island of Ireland there are water systems “where we just give the water away which is rarely a great idea”.
“In England there’s a particularly radical form of privatisation which you can argue hasn’t worked terribly well either.”
He pointed to water charging in the wider EU where there are a variety of models including metering.
“In terms of looking to the future there are probably a whole lot of models which work rather seamlessly it’s just that we’re closer to the ones that are particularly dysfunctional,” he added.