Aucklanders asked to use water wisely after treatment plants damaged from record-breaking floods

Siltation at the Lower Nihotupu dam in the Waitakere Ranges. Photo / Watercare

Aucklanders are being asked to use water wisely with reduced capacity at two water treatment plants and hundreds of stormwater issues still being addressed four weeks after the January 27 floods.

Watercare’s executive director special projects, Andrew Chin, said heavy rainfall from January 27 and Cyclone Gabrielle has caused major problems from siltation in the dams, knocking out the Waitākere water treatment plant and reducing the capacity at Huia.

The Muriwai pump station has been red-stickered at the coastal town, which is being supplied by water tankers. The Helensville reservoir is being filled up by water tankers working around the clock, he said.

“We have got services restored to a large extent but the system is still very fragile,” Chin told Auckland councillors today.

With less safety margin in the city’s water supplies, Chin said Aucklanders should treat water as being a bit precious, but by all means use water to clean up, but do not do things like filling swimming pools, he said.

Watercare is not considering water restrictions like those imposed during the 2021 drought, where Aucklanders were encouraged to have short showers and not water gardens without a hose nozzle, he said.

Healthy Waters is considering having dedicated days to clean catchpits, free of vehicles on the road. Photo / File

Meanwhile, the council’s Healthy Waters general manager Craig McIlroy said there are still 970 engineering stormwater investigations ongoing following the January 27 torrential rains.

The sheer scale of the wettest 24 hours ever in Auckland has required the help of 300-plus council staff, contractors, and consultants responding to stormwater issues.

McIlroy said the city has 115,000 catchpits on the roadside that Healthy Waters undertakes annual maintenance on, but the work is made difficult by cars being parked over them.

Healthy Waters is considering having dedicated days where kerbside sweeping and catchpit cleaning is done. Residents would have to find alternative parking arrangements.

“That is the sort of thing we probably need to do. In Japan they have forklift trucks that come along and lift up all the cars out of the way to do the cesspit cleaning.

“Moving forward, we don’t think the annual catchpit cleaning is good enough and we need to look at the ability for more funding to increase the frequency of cleaning,” he said.

McIlroy said piped infrastructure is only a small part of the stormwater network, saying a massive part is ground soakage and 16,000km of natural streams.