There are a number of beaches in the Auckland area with "do not swim" advisories following wastewater overflows.
According to Auckland Council's Safeswim website, overflows are more common in wet weather, but they can happen in dry weather too if pipes are blocked or damaged.
As of Tuesday afternoon, the beaches with black warnings - the highest in Safeswim's measures of whether a beach is safe to swim at - were:
North Shore
- Mairangi Bay
- Milford South
- Thorne Bay.
Central
- Herne Bay
- Home Bay
- St Mary's Bay
- Te Tinana
- Okahu Bay
- Point England
- Blockhouse Bay.
"Wastewater overflows occur when wastewater (sewage) spills out from gully traps, manholes, engineered overflow points or pump stations. It then flows into backyards or waterways and the sea," Safeswim said.
But the forecast for some Auckland beaches shows they will be back at safety level green by Tuesday evening, meaning there will be good water quality.
A map of Auckland's beaches and their safety levels is available here.
