He pushed a motion to have the Bulls' water independently tested by a recognised overseas laboratory.
"From information that's been available in the public ... it indicates the tests we are doing presently in New Zealand may only be picking up about 10 per cent of the potential problem," he said.
"If that is the case we need to know where we stand and we need to know urgently."
His motion was seconded by councillor Lynne Sheridan.
The chief executive, Ross McNeil, couldn't comment on what it would cost to do the tests, but said he had doubts over the difficulty of sending a sample overseas without it getting contaminated.
Several councillors indicated they would vote against councillor Platt's motion.
"For us to go zapping off to another country for more tests I do not believe that it's in our best interests," said councillor Dean McManaway.
"The New Zealand water authority levels are extremely high and we've got to rely on them for guidance."
The motion lost, with only councillors Graeme Platt, Lynne Sheridan and Cath Ash voting for it.
Councillor Dave Wilson then moved a motion to investigate the feasibility of doing an international test.
Councillor Soraya Peke-Mason asked whether the testing already done was in line with what was possible overseas.
Ross McNeil confirmed that what councillor Platt was requesting was an international test (known as a Total Oxidizable Precursor Assay) and not available in New Zealand.
All councillors voted to go forward with the motion to investigate the feasibility of an international test.