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Warm weather has again caused algae to become an issue for some residents on the Wanaka water supply, with the mains now being flushed in areas experiencing problems.
The problem also emerged in 2008 during similar conditions.
Wanaka Community Board chairman Lyal Cocks said the algae was a nuisance rather than a health risk.
A fine mesh filter over the water intake had not entirely prevented algae from being drawn into the reservoir's intake chambers.
Queenstown Lakes District Council water manager Gerry Essenberg said more work was being done, including water sampling.
The council has identified 13 different types of algae and needed a more detailed analysis before putting forward a cost-effective solution, he said.
The solution was likely to be a more detailed filtration system but, in the meantime, the council would continue to flush mains.
The council was also advising people with reduced water pressure to clean their filters or, if they did not know how to do that, call a plumber and have them checked.
Another option was for households to install a primary filter.
Mr Cocks said affected households needed to manage the situation until a solution could be found.