A Commission draft report on Coliban Water's pricing plan supports increases of 82.5 per cent for urban supply over a five-year period, taking an average family water bill from $586 to $1069 in 2013.

Public information sessions will act as one of the final steps before any further submissions close on May 9 and a final decision on future pricing structure is made by June.

The report recommends only marginal changes to Coliban's proposal of 85 per cent increases, with the major cut to come in proposed spending from halving the investment in its rural configuration upgrade down to $20 million.

It also allows for an operating cost of about $52 million per year and about $4 million per year in bulk water entitlements, including water purchased from the Goulburn system.

Coliban water managing director Geoff Michell said the ESC draft report largely vindicated Coliban's position that the price of water in the past had been too cheap to ensure water security and maintain an efficient system under increasing scarcity.

But he said the new era of pricing would also benefit frugal water users, by lowering fixed delivery costs and retaining the stepped tariff based on charging more for discretionary water use.

"The emphasis is to reduce the fixed charges and place more on volumetric charges," he said.

Mr Michell said the aim of price increases was to cover operating costs and fund urgent infrastructure and the authority would continue to advocate for its full proposed increases.

Mr Michell said Coliban had been collecting fees for up to 100 years and it had never been enough to fund operations and maintenance. He dismissed accusations that the authority had been drained by government dividends, having paid none since 2001.

Last year it had gained $40 million in additional State Government funding.