Southern Water informed the councils that it had carried out emergency works throughout the night to resolve the issue. However, waste is expected to remain in the area’s coastal waters until around 11am on Thursday 11th January.

The pollution is believed to affect the whole of Adur’s coastline from Lancing to Fishersgate, including the River Adur, and potentially Worthing.

The councils are urging visitors to the area’s coastline not to go into the water at this time and to take care on the beach in case waste has been washed ashore.

The Environment Agency has been informed about the leak.

Southern Water has said an electrical issue caused two pumps to fail at its Shoreham wastewater treatment works. This meant it was unable to release treated waste through its long sea outfall pipe so it instead released screened wastewater through its short sea outfall pipe, which is located around 500m offshore in the Shoreham Harbour area.

Southern Water stated it had used four tankers to relieve the pressure on our sewer network and reduce the amount of wastewater being released. It added that this action prevented homes and businesses from flooding.

Cllr Emma Evans, Adur’s cabinet member for the environment and leisure, said: “It’s deeply concerning that another leak has occurred in the area which could put our residents, visitors and animals at risk. We are demanding answers from Southern Water and assurances that this will not happen again.”

Cllr Vicki Wells, Worthing’s cabinet member for the environment, said: “I would like to know what caused the electrical issues at the Shoreham wastewater treatment works and expect assurances that they are being addressed urgently. I expect wastewater infrastructure to be robust - our communities and environment shouldn’t suffer as a consequence of ailing equipment. It’s unacceptable for the area’s coastline to be polluted by releases of sewage because pumps have failed.”