Complaints about ‘earthy’ tap water

Invercargill residents are upset about dirty tasting and smelling tap water.

Invercargill City Council water manager Alister Murray said the council had received 15 complaints about the ’’earthy’’ taste and odour in the drinking water on Thursday.

But while the taste and smell was unpleasant and inconvenient, it was not a threat to peoples health, he said.

The taste and smell came from compounds, 2-Methylisoborneol (MIB) and Geosmin, in the water.

The taste and odour coming from the compounds was prominent in summer because the compounds were intensified when the water was heated up, he said.

People often thought that boiling the water would counter the taste and smell, but refrigerating and using a lemon or orange was the best way to reduce the problem, he said.

‘‘Another factor is that the degree of unpleasantness varies from person to person depending on the sensitivity of their palate,’’ he said.

The council was working to resolve the problem, and had used powdered activated carbon (PAC) to counter the taste and odour of water since December 2016.

But on Thursday the problem was significantly worse for two reasons: the council had switched to a new batch of PAC which seemed to be less effective than the earlier batch, and it was further exacerbated by an equipment malfunction in the early hours of Wednesday morning, Murray said.

The Branxholme Water Treatment Plant is undergoing a ‘‘major’’ $11.5 million upgrade to improve overall treatment performance, which will help eliminate the issue.

‘‘The upgrade includes a new, more effective form of treatment than PAC by using ultra violet light with enhanced oxidation,’’ Murray said.