The federal government announced new legislation to provide safe drinking water in First Nations communities, but critics say the lack of firm funding is unacceptable.

The announcement came as a major fund for clean water on reserves is set to expire.

Government estimates released this week show the First Nations water and wastewater plan is scheduled to conclude at the end of March. Unless the government renews the fund, reserves will receive $159.2 million less in the next fiscal year.

A government assessment says it will take $5 billion over the next 10 years to bring water quality on reserves up to par.

"I don't see a plan," Liberal aboriginal affairs critic Carolyn Bennett told The Canadian Press. "This is unacceptable to be doing this piecemeal."

Aboriginal Affairs Minister John Duncan made the announcement Wednesday afternoon in Calgary, his second try to legislate clean water on reserves.

First Nations called the first bill "deeply flawed" because it overrided their treaty rights and Duncan pledged to revise the bill.

So far, the Conservatives have budgeted $2.5 billion over seven years for clean water on reserves. While no funding is yet attached, Duncan's spokesperson said the new bill will build on that investment.

"We will continue to make important and strategic investments in infrastructure, monitoring and capacity," Jan O'Driscoll wrote to The Canadian Press in an email.

A government-commissioned report showed 39 per cent of reserves had water that was at a "high risk" of being unsafe, and 34 per cent was at a "medium risk."