The Safeswim website shows black pins at some Auckland beaches. Photo: Screenshot / Safeswim
The quality of water at some of Auckland's central beaches is still not good enough for safe swimming, five weeks after a sinkhole caused a water and stormwater pipe to burst.
Auckland Council is keeping an eye on a number of inner city beaches which have been marked 'do not swim' on its Safeswim website.
Council head of Heathy Water Nick Vigar said where the black pins are on the Safeswim map - broadly Herne Bay to Ōkahu Bay - there is greater uncertainty about the water quality.
"To be clear, that means most of the time the water is testing fine but we're getting occasional samples or we're getting results that are higher than we would normally expect.
"And so from an abundance of caution, we're keeping black pins up until we're confident of the water quality."
"It doesn't take very much increase in flow for some of our aged sewer network to have issues" - Nicky Vigar
Testing was being done at least every couple of days at those beaches.
At least three days of clear results was needed for it to be marked green - or safe to swim at.
But, for example, if one of these days comes in just below the threshold, it would not count as a clear day, he said.
Sentinel Road Beach is still unsafe for swimming. Photo: RNZ / Anusha Bradley
The threshold for swimming in salt water in New Zealand is 280 enterococci per 100ml. Enterococcus is an indicator bacteria.
"Most of the time our beaches would be well below that, so anything over 100 would be unusual in dry weather."
Current issues are a flow on effect of the Parnell sinkhole, he said.
But asked if it was residual contamination from that, Vigar said the council was not sure.
"To our knowledge, there are no dry weather issues at the moment and the pump over that's there as far as I understand is capable of handling dry weather flows.
"But it doesn't take very much increase in flow for some of our aged sewer network to have issues."