Complaints of mouldy tasting water will be washed away if an ultrasonic transmitter installed to combat algal bloom in one of Dunedin's water reservoirs does its job.
About 30 residents complained to the Dunedin City Council late last month of foul-tasting water, which water production manager Gerard McCombie said was caused by cyanobacteria, an algal bloom.
To target the bacteria, one transmitting unit was installed at the Southern Raw Water Reservoir, near Brockville, last week, with a second to be installed this week.
"It is hoped to eliminate, or significantly lower, the remaining levels through the deployment of the transmitters," Mr McCombie said.
The units, which together cost $25,000, are installed below the water's surface and transmit ultrasonic waves to affect the cell counts of cyanobacteria.
Bacteria levels were well below the drinking water standards alert level, but the council was trying to reduce counts to a level where nuisance compounds were no longer detectable by consumers, he said.
Independent scientists are taking daily water samples to monitor bloom levels.
This testing will continue for an unspecified length of time to determine the effect of the transmitters on the bloom.
Repeat tests will also be run for cyanotoxins, which were negative in earlier testing.
Other non-toxic compounds, sometimes generated by cyanobacteria, will also be tested for as they are believed to create the taste and odour residents complained about.
The Southern Raw Water Reservoir supplies the Southern water treatment plant, which provides about 30% of the city's treated water daily.
