What is the taste and odour from drinking water in the Carron Valley water treatment works supply zones?

The reason for this is a harmless, naturally occurring organic compound called Geosmin which has been detected in drinking water samples from this zone.

Is the water safe to drink?

Although the taste and odour can be unpleasant, Geosmin is not harmful to health. The water continues to be rigorously tested in our laboratories and we can confirm the absence of harmful bacteria and other pathogens. The water is safe to use as normal and does not pose a risk to public health.

What is Geosmin?

Geosmin is associated with the breakdown of algae and other micro-organisms in the raw water sources. It has a distinct earthy/ musty taste and odour and is present in some foods such as beetroot, spinach, and mushrooms. It contributes to the strong scent in the air when it rains after a dry spell of weather or when soil is disturbed.

Geosmin can be detected by some people even at very low concentrations. The threshold for human detection is approximately 15 nanogrammes per litre. However, variations in customers’ perception of taste or odour, means some people may detect Geosmin at concentrations as low as 5 nanogrammes per litre in drinking water which is equivalent to 1 teaspoonful in 200 Olympic swimming pools!

How long will the taste and odour last?

Geosmin is present in the raw water at varying levels throughout the year but concentrations can significantly increase during the warmer months. It is difficult to predict how long these levels will remain elevated.

Carron Valley has a permanent treatment process in place to assist in the removal of Geosmin, however recent warm weather has contributed to a significant increase in raw water Geosmin. Scottish Water is continuing with operations to further optimise this treatment process and it is expected that this work will lead to a reduction in Geosmin levels. Scottish Water is carrying out frequent sampling of the water treatment works and network.

Why is the smell more noticeable in hot water than in the cold?

The smell is more easily detected in the shower or when water is heated for hot drinks as heating releases the compounds into the atmosphere as steam.