A water company has blamed its online system for reporting a 650-hour sewage outpouring in error.

Southern Water has an online tool called Beachbuoy which records storm overflows, when excess water in systems is pumped into the sea.

The company said that Beachbouy incorrectly indicated a lengthy release from Chichester Harbour running from December 23 through to January 18.

In fact, there were 19 short releases, which the company said had a much smaller overall flow volume.

Southern Water said its storm overflows are essential to prevent flooding and other damage to homes when there is heavy rainfall.

A spokesman for Southern Water said: “Following significant rainfall in recent weeks, these flows were almost entirely made up of groundwater, which had found its way into our sewer pipes.”

The company said its overflows are permitted by the Environment Agency.

Toby Willison, Southern Water’s director of environment and quality, said: “Excess flows like these are meant to be released via the UK’s existing network of storm overflows, to avoiding flooding people’s homes and communities.

“However, we know this is not an acceptable system moving forwards. This is why we have made reducing storm overflows our biggest priority, and we are already leading the water industry in exploring innovative engineering and nature-based solutions to how we can separate surface and groundwater from our network.

“Longer term, we have recently submitted a programme to the Environment Agency to spend up to £1 billion to cut storm overflows across rivers and the coast.

“This will start in 2025, focusing on beaches, areas with shellfish and other environmentally sensitive areas, including Chichester Harbour. In addition we are accelerating investment into the next two years to kick start this programme.”