A total of 10 town and rural water schemes are subject to boil water notices in Clutha at present, after Tapanui joined the list on Friday.
Clutha District Council deputy chief executive Jules Witt acknowledged the number might seem high, but said changing regulations — particularly around protozoa compliance — meant officials had no choice.
In addition, the council was investing significantly in upgrading water infrastructure across the district, which meant some existing infrastructure was nearing end of life.
Mr Witt said the council appreciated residents’ patience while works were completed.
"Historically, we hadn’t put boil water notices on for protozoa non-compliance, and we had highlighted a programme of improvement in previous years.
"That approach was not appropriate with the new rules and the approach taken by [Three Waters regulator] Taumata Arowai. All non-compliance now results in boil water notices which is why they are more frequent than in the past."
North Bruce and Moa Flat rural water schemes remained on long-term boil water notices, Mr Witt said, due to non-compliance as a result of tighter drinking water standards, which were being addressed.
Waitahuna, Balmoral and Tuapeka East and West would remain on long-term boil water notices until the new Balmoral/Tuapeka Rural Water Scheme and Lawrence new supply were commissioned.
These were due for completion by the end of May.
"It is important to note that after this phase, as part of fully commissioning the scheme we will need to flush the reservoirs and network of pipes to eliminate any non-compliant water from the network. Consequently, the boil water notice will remain in effect until ... the water is safe for consumption."
Stirling, Benhar, South Bruce and residents in Cherry Lane, Balclutha, had been on boil water notices since October’s extreme rainfall and flooding, damaging their water treatment plant.
"Damage from the flooding was extensive, making water treatment impossible.
"The repairs are expected to be fully completed by mid-February. Following this we will begin reticulation sampling and flushing of the network."
The most recent notice came into force in Tapanui on Friday, Mr Witt said.
"This was due to difficulties treating the water coupled with some treatment errors that saw the supply be non-compliant for a short time over the allowable limit. We would need three days of clear samples, and the treatment plant to continue to provide compliant water, to lift the notice, which we hope to be able to do in the next day or two."
