Health authorities investigating the contamination of drinking water at Tangalooma Island resort are looking into the possibility that sewage or other contaminants have polluted the island's natural ground water.

Key points: Sixty people, including six children, have reported fallen ill after visiting Tangalooma

Sixty people, including six children, have reported fallen ill after visiting Tangalooma New advice tells guests to only use bottled water as the bacterial infection may not be avoided by boiling

New advice tells guests to only use bottled water as the bacterial infection may not be avoided by boiling Authorities have not ruled out the possibility that the ground water may be polluted

Staff and guests are now being told to only use bottled water and scrap previous advice about boiling water.

At least 60 people, including six children, are believed to have fallen ill, from one tour group.

Dr Kari Javenin from Queensland's Public Health Unit said the bacterial infection may not be avoided by just boiling.

"It is now only commercially bottled water that may be consumed," Dr Javenin said.

"Previously we said that it is OK to consume bottled water. That has been upgraded due to further information and toxins present in the water that is not comprehensively or completely destroyed by boiling.

"So from now on the advice will be, and this has already been communicated to Tangalooma resort management, consume only commercially bottled water until further notice. And that includes for brushing teeth, also preparing food, washing vegetables."

Queensland Health launched an investigation after reports of sickness at the resort. ( ABC News: Ashleigh Stevenson )

He said authorities have not ruled out the potential that the ground water naturally filtered by sand on the island may have been polluted.

"We are looking at each and every potential. That is certainly being looked at among many other things," Dr Javenin said

"The investigations are still underway and we are getting more expert consultation and further specialised testing will be needed to be carried out to really answer that, but I can assure you that every angle is under consideration."

A page on the resort's website said it sourced drinking water from a natural underground water table, which starts about 1.5 metres below the surface of the sand, extending 40 metres below to bedrock.

"As the sand grains on the island are only tiny in size, it is an extremely efficient way of filtering the rainwater and we tap into this and supply the resort with the most pure and natural potable water possible," the website said. "The resort only uses a fraction of the water (less than 1 per cent)."

The website before the page became unavailable. ( Supplied )

That page has since been deleted.

The state's chief health officer, Dr Jeannette Young, issued a 'Public Health Matter of State Significance' notice on Wednesday, giving investigators greater power.

Health Minister Steven Miles said finding a quick solution to the problem required a joint effort.

"Ultimately this is a responsibility of Tangalooma and Brisbane City Council," Mr Miles said.

"However, because Tangalooma is really one of the jewels in the tourism crown of our state, this step recognises how important it is that guests from all over the world know that they can visit Tangalooma and do so safely."

Authorities have ordered the resort to install filters on its taps and immediately increase the treatment to the resort's pool.

The resort said it had carried out a chlorination treatment to improve the water quality. ( YouTube: Tangalooma Island Resort )

Resort management declined to answer specific questions about the handling of sewage on the island but a spokesman said it was fully cooperating with the investigation.

"The health, comfort and safety of our guests, staff and residents of the island is our priority and we have provided a free alternate bottled water supply, which is available at many points across the resort," he said.

"We are cooperating fully and following the advice of Queensland Health and Brisbane City Council (BCC) with reservations for current and future guests remaining in place.

"We are awaiting the results of water quality testing being undertaken by Queensland Health, so that we can work with them and BCC to determine the appropriate actions."