Brits are using more and more wet wipes and kitchen roll as toilet paper, and flushing them down the loo amid the coronavirus crisis.
The products, labelled as "unflushables" by the authorities, are clogging up pipes and drains.
They're combining with fats, oils and grease to create fatbergs - huge, solid masses which are difficult to clear and can cause raw sewage to build up and flood homes, businesses and the environment.
Thames Water has today discouraged the use of the products.
But shoppers currently face the prospect of empty shelves in supermarkets when they go to buy toilet rolls .
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Shops have reported running out of toilet paper as shoppers buy in bulk as a result of the pandemic.
Matt Rimmer, Thames Water's head of waste networks, said: "We're carefully planning how we can continue to provide an essential public service and while we encourage everyone to practise good hygiene to protect against Covid-19, wet wipes and kitchen roll can be hugely damaging to our sewers and our customers can really help us by not flushing them down the toilet.
"This will reduce the number of blockages and the risk of flooding to homes, businesses and the environment during what is likely to be a difficult time for many people.
"Fatbergs grow slowly so it's hard to say if coronavirus has had an impact on our sewers at this stage but, as always, we'd urge everyone to only flush the 3Ps - pee, poo and paper - to help avoid problems in the future."
Other goods, such as sanitary products and nappies, are "unflushables" for similar reasons and Thames Water reminds us shouldn't be discarded down the toilet.
On average, Thames Water spends £18 million every year clearing 75,000 blockages from its sewers, unclogging five house blockages and removing 30 tonnes of material from just one of its sewage treatment works every day.
The company is also fearful of an increase in staff absence in the coming weeks due to the flu-like virus.
Some businesses in the UK are asking staff to work from home where appropriate but the government stresses this isn't essential at this stage.
More than 1,100 cases of Covid-19 have been confirmed in the UK.
