Icon Water's annual report shows the water and sewerage provider received $454 million in revenue last year, up $25.4 million on 2016-17, largely due to an extra $16 million in water revenue linked to a 2.2 per cent price rises, greater consumption and growth in new connections.

That compared with payments to the ACT government totalling $122 million in 2016-17, with the dividend payout ratio set at 83 per cent for 2017-18 after tax, gifted assets and capital contribution revenue.

That was before a new pricing regime was approved last year that would decrease water prices paid by residential customers but also double the fixed supply charge for all customers over five years.

That proposal also allowed significant price falls for tier two water consumers in the ACT, which consume 200kl of water a year, and a $42 a year saving for residential customers.

While prices will continue to increase for the next five years in Canberra, the rises allowed by the Independent Competition and Regulatory Commission were far less than Icon's 2016 proposal for what would have been a one-off $500 increase under the last review of the water tariff system that year, and remain lower than 2017-18 price.

The revenue boost outweighed its $373 million in spending in 2017-18, up $14 million due to higher employment costs and an extra $3 million in tax equivalent payments due to higher profit.

The water provider, which holds a 50 per cent stake in electricity provider ActewAGL, also received an extra $5.4 million from its stake in that corporation, due to higher profit margins there, an extra $4.5 million through its sewerage operations, also due to rising customer numbers and higher prices.

Overall profit for the year was $107 million, up $11 million on the $96 million profit reported in 2016-17.

A spokeswoman for Icon Water said despite the latest price rises contributing to higher revenue and dividends to government, the utility estimated a likely $30 million fall in net profit after tax next year, down to $76 million.

But, she said this was due to an expected 3.5 per cent fall in 2018-19 in average residential water bills, as outlined in the commission's final price determination, compared to Icon's original pricing proposal put to the regulator for the next five years.

The Icon spokeswoman also said the utility had an extra 5000 new water connections last fiscal year, compared to about 3000 in 2016-17, which contributed to the revenue rises.

Its annual report shows Icon investigated 12 allegations of water theft last fiscal year, five of which were substantiated, four of which were referred to another authority and the remainder were not substantiated.

The corporation refused to detail what, if any, penalties were imposed on any of the companies or individuals involved in the substantiated thefts of ACT water, citing confidential provisions in agreements reached with the parties involved.

The Icon spokeswoman said in 2017-18 57 per cent of water sales were to tier one, or largely residential consumers, who on average consumed about 197kl that year, but did not detail the average consumption of tier two consumers, which are commonly clubs, sporting grounds and the like.

"Canberra is a very water conscious community and usage remains conservative following the behaviour changes made by the community in response to the millennium drought," she said.

Correction: This article has been edited, to correct an error which incorrectly reported average residential water prices would rise up to $27 in 2018-19. Prices will actually fall about $42 in 2018-19.