Formerly known as Adani, the central Queensland operation was at the centre of questions by Greens state MP Michael Berkman during budget estimates this week.

Berkman pushed the boss of state-owned corporation Sunwater about contracts with the coal mine during a hearing on Wednesday night.

“We apply a consistent approach to all industrial customers. All our contract details with our Sunwater customers are, in fact, commercial-in-confidence,” Sunwater’s chief executive Glenn Stockton said.

Documents obtained by a Right to Information request by the Australian Conservation Foundation showed Sunwater has previously held contracts with Bravus, Berkman said.

“Despite being a government owned corporation, am I to assume that you could not tell me how much water Sunwater has agreed to provide to Adani (now Bravus) and for what cost?” he asked.

While those details weren’t disclosed, Stockton says water provided to customers through the Bowen Basin is supplied from the Burdekin River by the Burdekin-Moranbah pipeline and the Eungella Dam via the Eungella pipeline.

Queenslanders deserve to know how much water the mine is getting, how much is paid and what it’s being used for, Mr Berkman said in a statement on Thursday.

“I’m pretty sick of the government hiding behind ‘commercial-in-confidence’ as an excuse to avoid basic transparency, particularly on a project like this with such significant public interest.”

A spokesperson for Bravus said the company pays for the water it uses and “like for other businesses, these arrangements are commercial-in-confidence”.

“The Carmichael Mine has the requisite water licences and access agreements in place for operations and is already producing high quality coal for export as part of an affordable and sustainable energy mix that includes generation from Adani’s extensive renewables portfolio,” they said.