Mission Bay Beach Photo: RNZ / Cole Eastham-Farrelly
'Do not swim' warnings on Auckland beaches are likely to be lifted today - as long as there is no more rain.
The council's water quality monitoring website, Safeswim, issued numerous high-risk alerts on Sunday, including at Mission Bay, Kohimarama, and Herne Bay.
The beaches were deemed unsafe to swim at after recent heavy rain caused sewage to leak into the water.
On Monday morning, Safeswim's website still had 10 beaches marked 'very high risk', where wastewater overflow has been detected, including Mission Bay, St Heliers and Herne Bay.
Eight others were 'high risk', which meant the levels of faecal indicator bacteria had breached national guidelines for swimming.
Safeswim programme manager Nick Vigar said it was a common problem after heavy rain.
"It's largely due to hundred-year-old combined drainage networks.
"The western isthmus programme and the eastern isthmus programme, which are in train at the moment, will over time attend to those, but that's big investment that's coming down the line over the next 10 years or so."
Most of the rainfall was on Saturday night and Sunday, so the warnings were gradually being lifted on Monday.
'High risk' warnings stayed up for 48 hours after a sewerage system overflow as a precaution.
No warning signs were on the beaches, Vigar said, so people had to check the website to find out when alerts were put in place or lifted.
About two thirds of Auckland beaches were safe to swim in, he said.