Tauranga City Council is warning people to stay out of the water in Pilot Bay due to a wastewater overflow this afternoon.
Warning signs are in place at the beach and water quality samples will be taken to check bacteria levels in the water at regular intervals.
The cause is believed to be a pipe which became blocked with wet wipes, causing an overflow.
Results of tests are due on Tuesday and people are urged to stay out of the water until then.
The water will be safe to swim again once the signs are removed.