The water and sewerage supplier's annual report shows Icon Water's profit jumped from $97.7 million to $122.3 million from 2014-15 to 2015-16.

That $24.8 million rise in profits was mainly driven by a jump in water and sewerage profits as well as higher "gifted assets", up from $10.5 million in 2014-15.

Those assets were infrastructure that private developers built in new developments in Coombs, Campbell, Lawson and the Kingston Foreshore, before giving them to Icon as part of standard development arrangements.

Water revenue was up $12.6 million, from $173 million in 2014-15 to $186 million in 2015-16; while sewerage revenue rose $5.2 million from $116 million in 2014-15 to $121 million in 2015-16.

Both those increases in revenue were down to increasing numbers of customers across the ACT.

A spokeswoman for Icon Water said the utility gained an extra 2000 water connections and an extra 3000 sewerage connections during the financial year, bringing the total connections across Canberra to 169,000 and 168,000 for water and sewerage, respectively.

But despite the rise in customer numbers, she said water consumption had "steadily declined" over the last three calendar years, down from 48.53GL in 2014 to 46.87GL as of late December this year.

Overall, the water supplier recorded $450 million in total revenue, against $327 million in expenses, delivering $84 million in dividends and $50 million in income tax-equivalent payments to the ACT Treasury's coffers.

Total income for the year fell from $269 million in 2014-15 to $130 million in 2015-16, but that change followed a revaluation of the property, plant and equipment Icon Water jointly owns in the ActewAGL electricity business, which had no material effect on the water supplier's bottom line.

The report also showed the water supplier received some seven allegations of possible fraud, but the spokeswoman said all had been found to be "unsubstantiated".

It also documented Icon Water's work on a corporation-wide business transformation project, which managing director John Knox wrote aimed to ensure the workforce was "highly competent', used "best practice processes" and had the right technology needed to do the job.

There were also major internal reviews of the corporation's "people strategy" and work health and safety strategy during the year, including work starting on a mental health initiative and a "safety engagement program" to be rolled out this fiscal year.

Mr Knox wrote that "significant progress" was made in reducing incidents and serious injuries, with a "55 per cent reduction in the serious injury frequency rate" and a 47 per cent fall in the number of "medical treatment injuries".

"No serious injuries (more than five days off work) were reported in the last seven months of the financial year," he wrote.

"These results demonstrate that our incident reporting, investigations and early intervention strategies are leading to positive outcomes."

Mr Knox also wrote that Cotter Dam had reached 75GL at the end of June, about 20 times its previous 4GL storage capacity and that the city's water storage was "healthy and brimming", while the dam was at 97 per cent capacity as of this week.