Thames Water have been fined more than £3m after admitting polluting rivers.
The company, which supplies one in four people in Britain with water, pleaded guilty to four charges.
It was fined £3.3m at Lewes Crown Court on Tuesday.
The court heard that an estimated “millions of litres” of undiluted sewage was pumped into the Gatwick Stream and River Mole between Crawley, in West Sussex, and Horley, in Surrey, on 11 October 2017.
The hearing was told that the spill turned the water “black” and killed more than 1,000 fish.