Water companies are asking customers to be careful what they flush after a rise in blockages caused by "toilet roll substitutes".
Thames Water said engineers had removed three huge blockages from the inlet filter screens at Beddington sewage works in Croydon in just three weeks.
Southern Water has also recently asked people to only flush toilet paper. Wet wipes or kitchen roll have frequently been found lurking in sewers in the past couple of weeks.
Beddington sewage works treats the waste water of 405,000 people in Croydon, Thornton Heath and Carshalton.