ABOUT 20 per cent of Hobart’s water supply is not receiving the required amount of fluoride.

A weak link in the supply of fluoride has been found at Lake Fenton, one of the three major catchments that supply drinking water to the greater Hobart area.

The State Government is required by law to make sure optimal levels of fluoride are put in drinking water, to ensure good dental health.

But scientists say the water at Lake Fenton, near Mt Field, is too “pristine” for the fluoride to mix properly, leading to a low pH level and below-par fluoridation levels.

Lake Fenton supplies 20 per cent of Greater Hobart’s water and is managed by bulk water authority Hobart Water.

Hobart Water chemical engineer Lance Stapleton said a new machine was required to fix the problem.

“Lake Fenton is a pristine alpine catchment and the chemistry of the water does not allow the fluoride to mix in properly,” he said.

“That means that over a year we see inconsistent levels of fluoride in the water.

“The fluoride also interacts with the chemistry and lowers the pH of the water, which has the potential to create rust in our pipes.

“We have been working for some time now on getting a project going to improve the fluoridation system, but we will require funding approval before the project can go ahead.”

Mr Stapleton said changing from the liquid fluosilicic acid, which is used now, to sodium fluoride powder was likely to solve the problem but new infrastructure would be required.

Despite knowing about the problem for several years, the State Government says it is still negotiating with Hobart Water, which manages its fluoridation assets.

Public Health deputy director Chrissie Pickin said there was no need for the Hobart community to be alarmed as fluoridation levels were “only slightly under optimal levels”.

Dr Pickin did not believe Hobart people’s dental health had suffered because of the intermittent fluoride supply from Lake Fenton.

“We have known about this problem for quite some time, but new technological advances now allow us to do something about it,” Dr Pickin said.

“There is still plenty of fluoride in Hobart’s water overall.”

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