Why is sewage closing beaches?

Swimmers and beachgoers are being advised to avoid going into the water after untreated sewage was discharged into the sea at nearly 50 UK beaches.

The pollution warnings were issued by the Environment Agency, which works to protect the environment in England.

Southern Water, one of the companies that has been criticised for releasing sewage into the sea told Newsround: "We want to reduce the number of times our sewers are overwhelmed by excess water entering our pipes, so we've set up a new team to find ways to get rid of rainwater in sewers and improve the pipes, sewers and pumping stations we already have. We also think sustainable drainage solutions and new technology, can all help."

So why has this happened and what are its effects?