It came as the Greens announced they would fund an independent water quality commissioner to rebuild people's confidence in their drinking water.

There have been chemicals detected in Tasmania's rivers 130 times since 2005.

Tourism Industry Council Tasmania chief executive Daniel Hanna said controversy over the water at St Helens had "absolutely" had an impact on the perception of Tasmania.

Mr Hanna said St Helens tourism operators confirmed they had seen some cancellations in the past week, but he said the impact had not been significant so far.

He said the sooner there was some evidence either way on toxic water concerns, the sooner the state could deal with any issues and move on.

St Helens general practitioner Alison Bleaney recently said she believed toxins from the leaves of plantation Eucalyptus nitens have been making residents of the East Coast sick.

Primary Industries and Water Minister David Llewellyn said the state already had an establised environmental protection authority, a well- respected director of pubic health and nationally accredited chemical testing laboratories.

He added that the state had a water policy that a recent review confirmed as being an effective tool in water quality management and which had led to significant improvements in management.

The State Government has said it would install carbon powder filters in the St Helens water supply.

Director of Public Health Roscoe Taylor has said there was no evidence to show that St Helens drinking water was unsafe but is seeking comprehensive testing from Dr Fiona Young, of Flinders University, who carried out tests for Dr Bleaney.

Greens leader Nick McKim said Tasmanians had lost confidence in the Government's capacity to properly monitor the state's waterways.

"Tasmanians have a right to clean, chemical- free drinking water," he said.

"The Greens will deliver this by creating a state water quality commissioner who is truly independent of government."

Under the Greens' plan, the commissioner would:

Carry out water testing.

Make recommendations about water infrastructure.

Prepare prosecution briefs of any breach of the Greens' chemical trespass legislation.

Liberal leader Will Hodgman said his party had already committed $950,000 to improve water quality testing, as well as to conduct an independent investigation of the concerns at St Helens.