Auckland's beaches have been overwhelmed by faecal bacteria after the recent bout of heavy rain.
Auckland's Council's water quality monitoring website Safeswim shows the public is warned against swimming at the majority of the city's beaches due to a high risk of illness.
The Safeswim map uses a 'green' water droplet icon for 'low-risk' beaches and a 'red' water droplet icon for 'high-risk' beaches.
And after the weekend's downpours, most beaches are red as Safeswim's water quality models predict that levels of faecal indicator bacteria breach national guidelines for swimming.
When contaminated by human or animal faeces, the water can contain disease-causing bacteria, viruses and protozoa (such as salmonella, campylobacter or giardia). These can cause illnesses including gastroenteritis, respiratory illness, ear and eye infections and skin infections.
In addition, there are multiple 'black' water droplet icons, which warn of an overflow from the Watercare wastewater network.
These have occurred at Chapman Strand, Taipari Strand, Herne Bay, Home Bay, St Mary's Bay and Te Tinana.
"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," the Safeswim site advises.
These wastewater overflows have a significantly higher public health risk than general stormwater contamination.
Watercare has multiple projects underway to reduce overflows, including expanding the wastewater network with projects such as the Central Interceptor pipeline, and building storage tanks to hold excess flows that would overload the network during heavy rain.
