Parliamentary hearings in Tasmania have seen TasWater’s upgrade plans savaged.

Two mayors - David Downie from Northern Midlands Council and Tony Bisdee from Southern Midlands Council - have delivered a scathing review of the state's water infrastructure and plans.

TasWater has spent $700 million fixing the state’s water and sewerage infrastructure so far, but costs are expected to hit $2.4 billion all up.

Councillor Downie – who is also the head of the TasWater owner representative group – says the costs of the desperately needed infrastructure upgrades will hit consumers.

“The bigger picture is, these assets are stuffed,” he said.

“Over the next six years the people of Tasmania are being asked to fork out some 30 per cent increase in water and sewerage costs.

“It is evident there are a lot of people in Tasmania living on welfare and their pensions only increase by CPI.

“People are under pressure from cost-of-living expenses, from the energy sector, from water and sewerage... there's a silent discontent in the community out there.”

Meanwhile, Cr Bisdee expressed his frustration at ongoing boil water alerts.

“As a tourist state, we cannot afford to have 24 towns on boil water alerts,” he said.

“It just doesn't fit the clean green image which we're trying to promote, and that's where all these tens of thousands, hundreds of thousands of tourists in the past and the future want to come and see.

“They expect to see a high standard of infrastructure in the state.

“That is the challenge, without huge increases, I'm not sure the Tasmanian community can afford to implement the full cost of upgrading in the next 10-year period, without outside assistance from state, or federal, or both.”

TasWater chairn Miles Hampton said “the plain simple fact” was that infrastructure was deteriorating “faster than we've been fixing it”.

Mr Hampton said there would be no compromise on over 600 capital works projects already underway, even though they require finding an extra $15 million in savings each year.