Report by ITV Meridian's Joe Coshan
A video has been released showing what appears to be sewage spilling into the sea off the Sussex coast.
Beachgoers are being warned not to swim in the water at Seaford and other areas, in case of sewage washing up on the region's beaches after heavy rain on Tuesday (16 August).
Footage of a large patch of dark and murky water where families are often seen swimming has been shared on Twitter.
Environmental campaign group Surfers Against Sewage say there has been storm discharge in Sussex and Essex.
Southern Water said 95% of the outflows - including the one in Seaford, are rainwater.
Councillor Matthew Bird, cabinet member for Sustainability at Lewes District Council has described the sewage release as a "new low", and is condemning Southern Water.
Councillor Bird said: “To see these sewage discharges into our seas, especially at time when many swimmers are taking to the water, is truly shocking and disheartening.
“Discharges are only supposed to take place after storm events and only because our water infrastructure is not fit for purpose.
“Like hundreds of other residents in the district, I swim regularly at Seaford and it is simply wrong that we should have to gamble with our health because of a lack of investment by Southern Water.
“Even by the miserably poor standards that Southern Water are infamous for, this is a new low.”
Speaking to ITV Meridian, Katy Taylor from Southern Water said: "There have been a number of releases over the last two days across parts of the south coast.
"Most of these releases are 95% rain water and run-off.
"The way the system is designed is that all the rain that falls, if it doesn't get soaked into the ground - which obviously when you've had a period of drought like we have had, the ground is very very hard.
"It becomes non-absorbant, so it's not absorbing that water.
"Most of the water is then run off down the side of roads, and down drains, and has gone straight into our works and out to the sea.
Katy Taylor from Southern Water responds to the Twitter video showing what appears to be sewage in the water off the coast in Seaford.
"That's water that you or I would walk in that is around us all the time, and it has to go somewhere.
"If it doesn't go out to sea, the alternative is that it will flood out houses, our schools and our hospitals.
"Unfortunately that's the way the system is designed. We are looking at whether we can change some of that, and whether there is a way we can reduce the amount of rain that goes through the run-off system that goes to those drains.
"So more gardens, less paved areas, more water gardens where water can be absorbed in the natural environment will all help with that.
"But given that especially across the south coast it's quite built up and a lot of housing growth, it's more difficult to find those green spaces to absorb that water."
In a statement an Environment Agency spokesperson said: “The thundery showers and intense rainfall over the last 48 hours increases the likelihood of storm overflows from the sewage system into the seas and rivers.
"We recommend that bathers take heed of any local warnings before heading into the sea.
“If any member of the public suspects pollution we would ask them to report this to our pollution hotline on 0800 807060.”