They are not pleasant to look at, and they are even less pleasant to remove.
They are the clumps of waste that form in drains and sewers from items that should never have been flushed in the first place.
Known as fatbergs, they are made out of wet wipes, condoms and tampons, which then cause fats and oils to congeal around them.
In South Australia, the cost of removing them is about $400,000 each year, and SA Water has launched a campaign — including a jingle — to remind people of what not to flush.
“It’s surprising that a lot of people actually don’t know what does break down and what doesn’t break down in the system,” said SA Water innovation manager Anna Jackson.
“It is, in fact, just the ‘three Ps’ that will go through the system nicely.”
In the words of the jingle, the ‘three Ps’ are “paper, pee or poo”.
“Everything else — the wet wipes, the nappies, the tampons, the pads — don’t break down,” Ms Jackson said.
“They sit up against a convenient tree root which might have grown into the sewer network looking for some water, and they form a blockage.
“It’s pretty disgusting … they can get enormous.
“The fatbergs in the London sewers — there’s been quite a lot of coverage of those recently.”
Fatbergs have gained notoriety in recent years, especially after giant ones were uncovered in the English capital.
South Australia’s drains are much smaller, meaning the masses of waste are nowhere near as big, but they can still cause blockages.
The issue has also been highlighted in Queensland, where water management authorities have to remove more than 4000 blockages each year.
SA Water said wet wipes made up a “significant portion” of the problem, which it described as “very disgusting and very avoidable”.
“When a foreign object, such as tree roots, kids toys or sprinkler heads get lodged in a pipe, more often than not, fat or wet wipes will accumulate behind the blockage,” Ms Jackson said.
“This limits the flow of water through the pipes.
“Our trade waste discharge regulations have helped avoid the large sewer blockages witnessed in other parts of the world, where fat and wet wipes have stuck together and caused severe obstructions.”
Ms Jackson said items marketed as “flushable” wipes should not actually be flushed.
SA Water said it would be releasing more images from its Christies Beach Wastewater Treatment Plant in Adelaide’s south across its social media platforms over the next few weeks.
“It’s asking the community to work with us on this because ultimately if you start flushing things down your toilet or your putting fats and oils down your drain, there’s a good chance it’ll actually block up right back into your house,” Ms Jackson said.
“A third of the world’s population not even having access to a toilet, I really think we need to appreciate our toilets.”