The union that covers Icon Water's engineering and technical staff, Professional Services Australia, said Icon renewed two contracts with ActewAGL for IT support, human resources, payroll, billing and economic advisers among other services in 2012, before embarking on a company-wide restructure less than two years later.

ACT director Dave Smith said Icon staff were now "stretched" after a hemorrhaging of professional expertise within the organisation, which staff were struggling to "reconcile" with the large contract which has not been open for tender.

Icon Water managing director John Knox previously defended the deal, saying it was better to "preserve those synergies [within the two businesses by re-signing the deal] rather than laying off a whole lot of people".

A spokeswoman later claimed the deal ensured customers were not hit with service interruptions or cost fluctuations.

But a former Icon staff member said the multi-million dollar deal raised eyebrows when it was renewed in 2012, despite the separation of the companies.

Staff asked if the deal should go out to tender, given they were forced to send far smaller contracts out to the market, they said.

Icon embarked on a capability assessment in 2013-14 which staff were told would not lead to a restructure.

"Within six to 12 months of that being finished, the restructure was announced. One branch after another were forced to reapply for their jobs," the former staff member said. He said about a quarter of staff had been shown the door.

An Icon Water spokeswoman said although the business was owned by the ACT government, it had a mandate to operate "as efficiently as any comparable business", which occasionally required restructuring. She said the restructures happened in accordance with the rules set out in the enterprise agreement.

However the union pointed out ActewAGL had a "seat at the table" with any Icon Water enterprise negotiations as it provided human resources and industrial relations support to Icon.

Mr Smith accused ActewAGL of "leading" Icon Water negotiations.

ActewAGL admitted two of their HR staff were a part of the negotiations but said the lead negotiator was an Icon Water employee and an Icon Water general manager had executive oversight.

Mr Smith said the services should be put out to tender "just to see whether they are in fact getting value for money out of the current arrangement". Failing that, Icon should release its contracts for public scrutiny.

"Icon Water is a 100 per cent territory-owned corporation and the people of the ACT have had whacks to their water bills and they've had whacks on the ActewAGL side to their electricity bills. They've got a right to know they're getting value for money out of these contracts," Mr Smith said.

But Icon Water said they would not release the contracts or a breakdown of what the $27 million per year provided, citing commercial in confidence.

The spokeswoman also hosed down claims the contracts and increases to water bills were connected, saying the price was set by the ACT's Independent Competition and Regulatory Commission.

However, opposition leader Alistair Coe said the contracts were part of the cost base Icon had submitted to the ICRC's pricing review, and therefore it stood to reason "water prices could be even cheaper ... had they not had a near $30 million component of their cost base passed onto consumers as a result of these two agreements".

He said the government could push Icon to publish the documents if it wanted.

"There are two shareholders of Icon Water, the chief minister and the deputy chief minister. The shareholders can dictate what this company does and it's up to the shareholders to act in the best interest of Canberrans and make this agreement public," Mr Coe said.