The only things that should ever go down a drain are water, human waste, and toilet paper. Everything else is a blockage waiting to happen.
Most of the blocked sinks and toilets we clear across Glasgow come down to a handful of everyday items that looked harmless going in, then set hard, snagged, or swelled once they reached the pipe. Here is what to keep out of your drains, and why the older pipework under a lot of Glasgow homes makes it matter even more.
What should you never pour down the sink?
Keep fat, oil, grease, coffee grounds, and starchy food waste out of the sink. None of it disappears once it is out of sight. It cools, clumps, or swells, then lines the pipe and catches everything that follows it down.
Fat, oil and grease
Fat, oil and grease cause more kitchen blockages than anything else we get called to. Poured down warm, they look like they have gone. A few feet along the cold pipe they turn back into a waxy solid, and every rinse of food scraps after that sticks to the layer already there.
Scottish Water reckons fats, oils and grease are a factor in more than half of all blockages across Scotland’s sewers. Let a pan cool, scrape the grease into a container or the bin, then wipe the pan with kitchen roll before it goes near the tap.
Coffee grounds, rice and starchy food waste
Coffee grounds do not break down in water. They sink, pack together into a dense plug, and bind with whatever grease already coats the pipe. Rice, pasta and flour do the opposite and swell, soaking up water until they form a paste that sets in the trap. Eggshells add grit that lodges in existing build-up. Bin them or compost them, and fit a cheap sink strainer to catch the rest.
Why do fat, oil and grease wreck drains?
Fat, oil and grease wreck drains because they cool and congeal into a solid mass inside the pipe, then trap everything else passing through. Given enough time and enough wipes to bind to, that mass becomes a fatberg.
A fatberg is congealed cooking fat locked together with wet wipes and sanitary products, and it can grow until it chokes a whole sewer. The one found under Whitechapel in London in 2017 ran 250 metres and weighed 130 tonnes, with wipes forming most of its structure.
Glasgow’s older streets make the problem worse, because much of the Victorian core runs on combined sewers where foul waste and rainwater share one pipe. A pipe carrying both has less room to spare when grease starts narrowing it.
What should you never flush down the toilet?
Only three things belong in a toilet: pee, poo and paper. The water industry calls them the 3 Ps, and anything outside that list belongs in the bin.
Wet wipes, kitchen roll, cotton wool and cotton buds, dental floss, sanitary products, nappies, and hair all cause the same trouble. None of them fall apart the way toilet paper does, so they stay whole, snag on the inside of the pipe, and give grease something to cling to.
On an average day Scotland has around 100 sewer blockages, and about 80 of them come down to items that were never meant to be flushed. Medicines should go back to a pharmacy rather than down the loo, since the treatment works cannot easily filter them out.
Are “flushable” wet wipes actually flushable?
No. Treat every wipe as non-flushable and put it in the bin, even the ones sold as flushable. The label has caused so much confusion that the industry has dropped it.
The Fine to Flush standard that Water UK once ran to certify some wipes ended in March 2024, and the industry message now is simply Bin the Wipe. Research for the UK water industry found wet wipes are involved in 94 per cent of sewer blockages, at a cost of around 200 million pounds a year that lands back on household bills.
A ban on wet wipes containing plastic is coming as well, taking effect in Scotland on 11 August 2027. Until then, the rule stays simple. If it is not one of the 3 Ps, bin it.
The tenement problem: what your neighbours flush affects you
In a Glasgow tenement, one flat’s habits can block the drain for the whole close. Flats above and below often share a single soil stack and a shared drain, so grease from one kitchen or wipes from one bathroom can back up into everyone else’s.
Older closes across the West End, Southside and East End were built with shared pipework that all feeds the same run, and a fair amount of it is still original clay or cast iron.
When a blockage forms in that shared section, it is rarely one household’s problem to fix, and sorting out who is responsible for a shared drain in a tenement can be a headache in itself. Keeping fat, wipes and food waste out of your own outlets is the cheapest way to protect the whole building.
What to do if something is already blocking your drain
If the water is draining slowly, backing up, gurgling or giving off a smell, stop putting anything else down it and get it looked at. Adding more water or a bottle of drain cleaner to a drain that is already struggling tends to make the mess worse.
Chemical drain cleaners are a coin flip at best, and on the older clay and cast-iron pipework common in Glasgow homes they can do real harm. A blockage that has built up over months of grease or wipes needs clearing at the source, which is a job for proper rods, jetting or a camera rather than something to keep fighting at the sink.
If the same drain keeps blocking after it is cleared, the cause is usually further down the line and worth understanding on its own.
When a drain has stopped running, the sensible step is to unblock a drain properly before it backs up any further. We cover Glasgow and North Lanarkshire within standard working hours, with on-call cover for genuine out-of-hours emergencies such as an overflow or a toilet that cannot be used. Call 0141 673 3535 and an engineer will talk you through it.
Frequently asked questions
What is the one thing you should never pour down the sink?
Fat, oil and grease. They look harmless going down warm, but they cool and set into a solid layer inside the pipe within a few feet, then trap food scraps until the drain blocks. Let them cool in a container and put them in the bin instead.
Are flushable wipes really flushable?
No. No wet wipe breaks down the way toilet paper does, so bin every wipe, including any labelled flushable. The Fine to Flush certification that once backed those labels ended in March 2024, and the water industry now asks everyone to bin the wipe rather than flush it.
What are the 3 Ps you can flush?
Pee, poo and paper. Toilet paper is made to fall apart in water within seconds, so it is the only paper that belongs down the loo. Kitchen roll, tissues and wipes stay intact and snag in the pipe.
Can you pour cooking oil down the drain if you run hot water after?
No. Hot water only carries the grease a little further along before it cools and congeals, so all you do is move the blockage deeper into the pipe where it is harder to reach. Cool the oil and bin it.
Can you put coffee grounds down the sink?
No. Coffee grounds do not dissolve. They sink, pack into a dense plug and bind with any grease already lining the pipe. Bin them or add them to a compost heap, where they do more good than harm.
Do rice and pasta really block drains?
Yes. Rice, pasta and flour keep absorbing water after they go down, swelling into a paste that sets in the trap. Even small amounts build up over time, so scrape plates into the bin or a food caddy first.
Who is responsible for a blocked shared drain in a Glasgow tenement?
The answer depends on where the blockage sits. A shared drain or soil stack within the tenement is usually the joint responsibility of the flat owners, while a public sewer is Scottish Water’s. Our guide to drain responsibility in a Glasgow tenement covers who pays in more detail.
Keep your Glasgow drains clear
Most blocked drains are avoidable. Keep fat, oil and grease out of the sink, stick to the 3 Ps in the toilet, and bin every wipe, and you will spare yourself the worst of what we get called out to across Glasgow.
When something does go wrong, catch it early rather than waiting for it to overflow. For drain unblocking across Glasgow and North Lanarkshire, call 0141 673 3535 and talk to an engineer who will give you a straight answer.
