The Cabinet will decide on the size of flat-rate water charges to be faced by schools at its first meeting in early January, Taoiseach Bertie Ahern has said.
Rejecting criticism of the Government, Mr Ahern said Ministers would draw up "a single comprehensive statement" to offer direction to schools when they meet on January 4th.
Schools will face, he said, a flat-rate charge based on their size, so that the school in Cahersiveen will not have to meet the same charge as a much bigger school elsewhere.
On Tuesday, the Cabinet decided to defer outstanding school water bills and committed to offer each school a per-head allowance of water before charges would be made.
"The length of [the deferment] has not yet been decided. While it can be up to the end of 2009, the Government must decide on its length," Mr Ahern told Fine Gael leader Enda Kenny.
"Schools should monitor water usage and institute repairs and conservation measures during this period.
"There already is support for so doing. The Government also has sought advice from the Attorney General's office regarding the long-term options," said Mr Ahern.
The programme for government agreed between Fianna Fáil and the Greens included a pledge that schools would be given a per-head water allowance before they would face bills," he said.
"This is the first time in my memory of implementing programmes for government that implementing a measure is considered to be a U-turn. This is extraordinary," he said.
The Minister for Education and Science, Mary Hanafin, acknowledged it had been "clear from the beginning" after meters had started to be fitted in schools that bills had risen.
Some schools now face water bills of up to €10,000 and Ms Hanafin advised that those schools with significant increases should "hold onto the bills for the moment".
The capitation grant for primary school students would be increased to €15 per pupil in January in line with the Government's commitment to double the grant over the next five years, she said.
Meanwhile, the organisation representing Irish primary school teachers said schools should write to local authorities officially to defer water charge payments until they receive ministerial clarification.
Chambers Ireland voiced concerns that the deferment of school water bills would have "serious implications for local authority funding", since the councils would be forced to make up for the loss of income elsewhere.