The process of treating raw water and turning it into trusted drinking water is complex. A number of naturally-occurring substances can impact the taste and appearance of treated drinking water, even in the tiniest amounts.
While elevated levels of geosmin in drinking water does not create any health risks, it can create a distinct odour, even at a concentration of just a 50-billionth of a part per litre. However, the drinking water remains safe and meets the Australian Drinking Water Guidelines.
To manage this, we continue to revise and adjust our treatment processes in response to the poor quality of the raw water entering our treatment plants.
Geosmin is a naturally-occurring compound found in water sources. It’s produced by a range of blue-green algae (BGA) and other harmless bacteria that live in our rivers and water storages.
During most of the year there will be very low levels of geosmin present in the water. However, levels can rise in warmer weather, when BGA and other bacteria grow and multiply.
This summer, high levels of run-off and other flood-related contamination have contributed to elevated levels of geosmin in the Murray River and its tributaries.
Geosmin can be detected by the human nose at extremely low concentrations.
When levels of this naturally-occurring compound are elevated, it can cause a strong earthy taste and odour.
Although the taste and odour caused by geosmin may be unpleasant, it’s an aesthetic issue and geosmin does not pose a risk to human health.
Treated drinking water that contains geosmin meets the Australian Drinking Water Guidelines and the Safe Drinking Water Act 2003.
We know this change is unpleasant for some customers and we continue to revise and adjust the processes at our water treatment plants to suit local conditions and the poor quality of the raw water.
Recently, we have seen much greater levels of geosmin in the raw water than in previous years. This has proved challenging for our water treatment plants as they work to completely remove the geosmin.
We are using ‘powdered activated carbon’ (PAC) dosing units to remove as much of the geosmin as we can.
This is an aesthetic issue. Treated drinking water that contains geosmin poses no health threats and meets the Australian Drinking Water Guidelines and the Safe Drinking Water Act 2003.
It may help to place a jug of water in your fridge. This helps aerate the water and can reduce the odour.
You may also consider adding a slice of orange or lemon, or some mint to your drinking water.