The video shows a pipe at Southern Water' s treatment facility in Havant pumping rainwater and sewage into Langstone Harbour..
Its comes ahead of the 2021 United Nations Climate Change Conference which begins on Sunday (October 31) and after MPs, including Gillian Keegan and Nick Gibb, voted not to force UK water companies to reduce sewage pollution until it is eliminated.
A spokesman for Southern Water said: "We do this protect people's homes, schools and businesses from flooding. During rain, 97 per cent or more of the water which ends up in our sewers is rain water and we use storm tanks to contain this and we only release when the storm tanks are full and the risk to homes is immediate.
"We are working on ways to reduce our reliance on the systems bit this will require multi-agency work."