Western Water has adjusted treatment systems to address a change in taste caused by low water levels at Gisborne’s Rosslynne Reservoir.
An additional treatment process was started this week after more than 40 calls were received from residents in Gisborne, Sunbury and Diggers Rest in the previous six weeks.
Customers also took to social media to ask about a change in the taste or smell of their drinking water.
A higher level of organics at Rosslynne was found to be the cause.
Western Water said it could be another few weeks before people noticed an improved taste, with water from the filtration plant taking time to work through the system.
However, it has confirmed that the water remains safe to drink.
Relatively wet weather this winter has not been enough to boost supplies at Rosslynne Reservoir, which services Sunbury and towns in the Macedon Ranges.
Customer and community relations manager Graham Holt said the storage was at 42 percent capacity, its lowest level since December 2010.
‘‘Rosslynne has been steadily dropping for the past 18 months, despite our customers’ drinking water use remaining fairly consistent with previous year,’’ he said.
‘‘Some customers have noticed a change in the water’s taste, due to the lower water level.’’
Mr Holt said in addition to changes at the filtration plant, Western Water had also conducted ‘‘targeted flushing’’ of mains to help move water through in areas where taste or odour problems had been reported.
‘‘We want to reassure customers that despite changes in taste, their drinking water is safe to drink.’’
