Under the plans, the average water bill would rise to about �407

South West Water (SWW) wants to raise bills by 22% by the end of the decade, saying the increases would pay for improvements in the supply network because some water mains are old and unreliable.

However, ministers want to cut water companies' spending on environmental improvements, leaving some scope to limit price increases.

Such increases have caused concern in government following the controversy about large council tax rises. Ministers have been looking at several ways to reduce them.

Draft plan

BBC South West environment correspondent Simon Hall said: "They want to cut planned environmental improvements to rivers and the sea, so requiring water companies to raise less money from bill payers.

"The government's proposals were due to be released this week, but arguments about how much bills can be reduced by mean that is not now likely for a fortnight."

However, even if the environmental programme is cut, it is unlikely to save consumers more than a few pounds a year.

Keith Richards from SWW said: "The government does have some limited scope to reduce the size of the quality programme on waste water if it wishes to.

"That would certaily konck �3 or �4 off of the average bill by 2010."

Last month, watchdog WaterVoice South West said many SWW customers would not be able to afford proposed price increases.

SWW announced it wanted to increase bills over a five-year period in its draft business plan for 2005 to 2010.

Under the plan, the average bill would rise by �73 to �407.

WaterVoice said many customers were already struggling to pay their water bills and there was a lot of hostility to higher prices.

SWW said its business plan was a realistic assessment of future need and that it did not want to have to raise prices.