So much so, that they have a word of its own - “fatbergs” - a combination of fats and “berg” from iceberg.
These fatbergs, lurking below the road system, can grow to obscene masses, such as the 130000kg fatberg pulled out of London’s sewers in 2017.
In New York City, the council’s environmental protection department recently launched an educational campaign called “Trash it. Don’t flush it” and “fatbergfree.nyc” to warn people about the dangers of simply throwing everything down the drain.
“With an ageing, overburdened sewer system, we must be vigilant about what we send down the drain,” said council member Costa Constantinides.
“It’s important we let New Yorkers know the ramifications of sending wipes, oils and other harmful materials through our beleaguered pipes.”
The city said: “Grease that is improperly poured down the drain is similarly causing blockages in the sewer system. In fact, it is the number one cause of sewer backups in New York City.
“Over time, the grease and improperly flushed items build up within the sewers causing fatbergs.”
Ads are being placed at subway stations and bus shelters, and on trains, buses, television and social media.
The council urges people to only flush the four Ps, those being pee, poop, puke and (toilet) paper.
They also urge people to never flush wipes or other trash down the toilet, even if the box is labelled as flushable, and never to pour grease down kitchen sinks or toilets.
“Instead, place grease in sealed non-recyclable containers and discard with regular garbage,” said the city.
eThekwini Municipality said it had not yet faced any fatbergs.
“The city has experienced the build-up of fats in some of its sewers. In some instances, the fats are cleared by regular dosing of the lines with special enzymes and bacteria that break down the fats and allow the sewers to flow freely. In other instances, the lines that are problematic are jetted to remove the fats.
“Most of the areas that experience this fat build-up are where there is a high concentration of restaurants whose fat and grease traps are not working. This is periodically addressed by our Pollution Division in conjunction with the City’s Health Department,” said municipal spokesman Msawakhe Mayisela.
He said there was no record of fat build-up in the trunk sewers and that the fat build-up was predominantly in the 150mm to 200mm sewers.
“The effect of ignoring the fat build-ups means the reduction in diameter of the sewers and as such insufficient capacity which would cause the sewer to overflow. The city is well aware of the problem areas and we are not experiencing any overflows in these areas,” said Mayisela.
Derek Shuttleworth of Envirodiesel, a company that collects used cooking oil and converts it into biodiesel in Cape Town, also advised against pouring used oil down a drain.
“But there is little one can do to dispose of it otherwise. It is a toxic waste product and the only suggestion is to seal the oil in a container for the toxic waste dumps operated by municipalities,” he said.
Shuttleworth said cooking oil was “quite a valuable commodity”. “All of the oil we collect gets converted into biofuel, but there are oil collectors purchasing the used cooking oil for bulk shipment to overseas biodiesel plants.
“This deprives our economy of the free carbon available and jobs that would have been created if it was converted into biofuel in South Africa.
“We have approached several government departments to get this stopped without any success or even interest,” he said.