Our toilet habits have not improved since the time of Thomas Crapper as bulky rubbish and even wedding rings and false teeth are flushed away.
The Consumer Council for Water urged Britons to be more careful about what they put down the loo, ahead of the centenary of Mr Crapper's death on January 27.
It said sewerage workers often find valuables such as jewellery or credit cards that have been lost down the toilet, and refuse including face wipes, condoms, razor blades, tampons and nappies, which should be put in a bin.
Three quarters of sewerage blockages are caused by things that should not have been flushed down the loo or put down the kitchen sink, such as fat.
Chief executive of the Consumer Council for Water Tony Smith said: "The early plumbers, sewer workers, inventors and entrepreneurs like Thomas Crapper did a lot to improve sanitation and therefore people's health here in the UK, but to help the system work properly we need to use it responsibly.
"People who put things they shouldn't down the loo could be flushing money away because the cost of having your own private drains unblocked can be expensive. If the public sewers are blocked, the sewerage companies' costs in removing blockages get passed on to customers via sewerage bills."
Mr Crapper was a plumber who made toilets and bathroom fittings in the 1800s.
When households began to have flushing toilets, scavengers would hunt for jewellery, coins and other valuables which had been lost in the system.