Paterson MP Bob Baldwin raised the claims in Senate hearings yesterday, accusing the government of jeapordising the water supply for the sake of less than $10 million.

‘‘The base has never been on the main sewer system,’’ he said last night. ‘‘The treatment ponds sit near the domestic terminal.’’

The Department of Defence confirmed the problem after the Senate hearings, saying effluent discharged from the treatment plant went into ‘‘evaporation/infiltration lagoons on the southern edge of the Tomago sandbeds’’.

Testing had revealed heavy metals at levels ‘‘generally below’’ the guidelines, the department said Hunter Water had been ‘‘comfortable with the risks to ground water’’.

The department said it was negotiating with Hunter Water to connect to the main sewage system.

‘‘Defence is unable to commit to a contribution of funds to the scheme until the terms of the agreement that would bind the Commonwealth to the Hunter Water Corporation for connection/s at RAAF Base Williamtown are finalised and the requisite government and parliamentary approvals are obtained,’’ a Defence spokesperson said.

Mr Baldwin, who worked with Queensland Senator Ian Macdonald on raising the issue during the hearings, said the risk to the sandbeds involved domestic and industrial waste.

‘‘Hunter Water is running the sewer system through the area and Defence’s contribution was less than $10million but they appear to have been withholding the funding,’’ he said. ‘‘This is not just household sewage. The base uses a lot of industrial chemicals with its washdowns and maintenance programs and the like.

‘‘Now that there’s a delay in Australia getting the joint strike fighters from the US, all of the urgency has gone out of modernising the Williamtown base.

‘‘But this sort of delay when drinking water is at stake is reprehensible.’’