Geosmin FAQ

Geosmin is a commonly occurring natural compound found in water sources. It can affect the taste and odour of treated drinking water.

Geosmin is usually more prominent during the warmer months when it is produced by blue-green algae in raw water storages like dams and weirs. It can alos be produced by bacteria in water and soil.

Learn more about blue-green algae

Geosmin has a very strong, earthy taste and odour. It can be smelled at very low concentrations (in the parts-per-trillion range). The compounds are generally present in all drinking water but below noticeable levels.

Although the taste and odour from Geosmin may be unpleasant, it is purely an aesthetic issue. Treated drinking water is safe to consume and meets parameters set by the Australian Drinking Water Guidelines and the Safe Drinking Water Act.

We appreciate people’s patience and understanding while we work to minimise taste and odour issues.

Our water treatment plants use ‘powdered activated carbon’ dosing units to remove Geosmin. The compounds bond with the carbon and are removed from the water. Unfortunately, sometimes not all the Geosmin can be removed, however this is purely an aesthetic issue and treated water is safe to consume.

Recently we have seen Geosmin levels up to 20 times more concentrated than in previous years. This has proved challenging for our treatment processes.

We have increased the use of carbon dosing to remove the compounds. We are also undertaking more sampling for Geosmin and adjusting our treatment processes as necessary.

Testing has shown there are higher than normal levels of Geosmin in the Mitta Mitta arm of Lake Hume at Tallangatta and in Lake Mulwala at Yarrawonga. There is the possibility that Geosmin concentrations in Lake Hume could increase in other areas as blue-green algae grows and produces the compound. This could include other areas of Lake Hume and/or the Murray River.

It is unclear on how long the high levels of Geosmin will last, however traditionally as the weather cools, levels of the compound decrease.

Some people have reported that putting water in a jug in the fridge can help with the taste and odour issues. You could also consider adding lemon, orange, watermelon or mint to help.

We realise water taste and odour is an issue for some customers, however we are unable to offer a refund or compensation as it is purely aesthetic. Treated drinking water is safe to consume and meets parameters set by the Australian Drinking Water Guidelines and the Safe Drinking Water Act.