Arrowtown residents have been asked to boil all drinking water since Tuesday morning, when a routine test sample showed traces of E-coli bacteria in the water.
Engineers from the Queenstown Lakes District Council have since been testing daily, both from the pipe which showed the contamination, and from bores and reservoirs.
QLDC general manager engineering services Mark Kunath said the tests from Wednesday and Thursday showed no traces of E-coli.
If the final extra test at noon today is also clear, the council will give the all-clear.
"When the test from the pipes showed contamination, but the tests from the reservoir were good, our instincts told us it was most likely a faulty test. But we still have to take all possible precautions, and follow procedures," Mr Kunath said.
After residents had expressed concern over not being adequately informed on Tuesday, Mr Kunath promised notices would be placed both on the council website and on noticeboards in Arrowtown, once the water was deemed safe to drink.
Until the all-clear is given, residents linked to the Arrowtown water supply should continue to boil their drinking water.
