Masterton people complaining of smelly tap water have been assured there is no health risk.
Low river levels and continuing hot weather combine at this time of year to present problems with the taste and odour of the town's reticulated water supply, according to Masterton District Council.
Spokesman Sam Rossiter-Stead said the combination of river levels and heat resulted in an increase in non-harmful algae growth in rivers.
"Our water treatment plant process ensures the water is safe to drink but unfortunately is unable to effectively treat all of the taste issues.
"Staff continually monitor the treatment process to make sure water quality remains at its peak," he said.