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'Earthy' Canberra water safe to drink, timeline for taste to disappear unclear

The strange taste in water is originating in Bendora Dam. Picture: Icon Water

Tap water in Canberra is completely safe to drink despite the earthy taste detected by some people.

"At the moment, it continues to be safe to drink," Ben Bryant, Icon Water's environment and sustainability manager, said on the ABC Radio Canberra.

"We are monitoring this event," he continued. Analysis of water had been increased.

He said he could detect the taste himself though others couldn't. It's been described as "earthy" or "mouldy".

"We are tasting nature," Mr Bryant said.

He said he didn't mind the taste but if people did, they could consider chilling water in the fridge or adding a slice of lemon. A filter might also work.

But some have complained on social media. "The dirty taste in our water supply means I can only handle it in tea until it's fixed," one said. He complained of "devastating headaches".

Another Canberran said on Facebook: "Have you tried boiling it in saucepan instead of jug as I've been boiling all our water lately including my animals'."

"The earthy smell and taste are due to natural compounds in the source water," the company said.

"Some people can smell and taste these compounds at very low concentrations (as low as 10 parts-per-trillion) but the concentration is usually below this range," it said on its website.

When the new taste was detected two weeks ago, Mr Bryant said: "We've detected the presence of this organic odour and taste compound that's originating in our catchment raw water supply under Bendora Dam in the Cotter and that's coming down through our Stromlo water treatment plant."

The taste comes from an organic compound, 2-Methylisoborneol (MIB), which occurs naturally in water sources around Australia and is "not a cause for concern".

"It comes from a lot of different environmental sources and we know one of those sources could be an algal bloom but we've discounted that," Mr Bryant said.

"What we think might have happened instead is we know the water has turned over in Bendora catchment, so it's a bit like a lasagna, usually water stratifies out at different temperature levels.

"From time to time it turns over and mixes up and usually on the top two-thirds of Bendora mixes but in this instance, what's happened is it's mixed through the enter water column and so we think it might have stirred up some of the sediment on the bottom of the reservoir."

The heavy rain could be a factor. "It's hard to give a timeline of when it might become less noticeable," Mr Bryant said.

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