Tauranga City Council is advising that all Tauranga waterways where flood water from the weekend's torrential rain has collected should be treated as potentially contaminated.

TCC says all waterways including the harbour, open drains, streams including parts of Pilot Bay, Matua, and Waimapu and Waikareao estuaries are affected by sewer overflows.

Coronation Park is contaminated following flash flooding at the weekend.

Contamination could be from sewer overflows in particular, but also from flood water that has been through industrial areas, garages and storage sheds.

TCC advises the following areas are affected:

- Coronation Park, affecting Pilot Bay

- Beach Road, affecting the Matua foreshore

- Fraser Cove, affecting Waimapu Estuary

- Third Avenue affecting Waikareao Estuary

- Chapel Street/Maxwells Road affecting Waikareao Estuary

The Chapel Street overflow was a controlled release of treated wastewater from the Chapel Street plant. This was necessary for 20-30minutes on Saturday morning after the treatment plant became overwhelmed with double the usual volume of water that was entering the wastewater system.

Health warning signs have been installed at the affected areas. Water quality testing will be done this week.

Please note it is always recommend that people stay out of the harbour for at least 48 hours after heavy rain due to potential contaminant run off from roads and urban areas.