What you should never flush down the toilet or pour down the sink

Practically every domestic blockage we deal with has the same origin: something went down a drain that shouldn't have. We're not talking about odd accidents, but everyday habits almost nobody associates with a breakdown — emptying the frying pan into the sink, flushing a wipe, rinsing a paint brush — which, repeated over months, end up forming a plug that a rubber plunger can no longer shift.

The good news is that this is the easiest part of home maintenance to prevent. It needs no building work, no inspections and no spending: just knowing what goes in the bin and what goes down the drain.

Wet wipes: problem number one

If we had to name a single cause, it would be wet wipes. And the confusion isn't the user's fault: plenty of packaging is marketed as disposable or biodegradable, and that reads as "safe to flush". It isn't the same thing. Toilet paper is manufactured to fall apart in seconds on contact with water; a wipe is manufactured to do precisely the opposite, to hold together while it's used. It reaches the pipe intact and catches on any bend, joint or irregularity.

From there the process is always the same: the first wipe holds back the next, the mass traps grease and hair, and within weeks the usable pipe section is reduced. By the time the blockage shows itself, it isn't one wipe: it's hundreds, compacted together. It's also the most frequent cause of the emergencies we attend in the early hours, because the plug finishes closing at the worst possible moment. The same logic applies to sanitary products, cotton buds, dental floss, condoms and cotton pads: none of them disperse, all of them snag.

Oil and grease: the blockage that builds slowly

Oil is the second big culprit, and the quietest. It leaves the sink liquid and hot, so it feels as if it's gone without trace. A few metres on, meeting cold pipe, it solidifies and sticks to the wall. Every repetition thickens the layer. Over months, that hardened grease traps food waste, hair and soap, and ends up forming a dense plug that neither hot water nor detergent will dissolve.

The very hot water and washing-up liquid trick doesn't avoid the problem: it just pushes the grease a little further along, into a stretch you can't see and where the blockage will be more awkward to clear. The same applies to sauces, butter, cream and fatty stock. In restaurant, bar and hotel kitchens the effect multiplies, which is why network maintenance and grease traps matter so much in the island's commercial installations.

The bathroom: what seems harmless and isn't

Beyond wipes, there's a list of regulars worth keeping in mind. Hair, which closes a shower drain within months through accumulation alone and is solved by a two-euro strainer. Cat litter, including the kind sold as flushable, because it's designed precisely to compact with moisture. Medicines, which neither break down nor belong in the drainage network. And thick cleaning-product residues, or the small objects that fall in by accident and sit across the trap.

Dental floss deserves a special mention: it's thin, it doesn't break, and it works like a net that catches everything else. It's remarkably common to find it forming the skeleton of a plug.

The kitchen: food waste, coffee and rice

At the sink, besides grease, there are three suspects. Coffee grounds, which don't dissolve and cake up in the bends into a compact paste. Rice and pasta, which keep absorbing water inside the pipe and swell. And peelings, skins and vegetable fibres, which tangle together. They all share the same trait: individually none of them blocks anything, but they accumulate in the same places, month after month, until one day the water stops going down.

Building waste is a separate and particularly damaging case. Rinsing paint, plaster, cement or adhesive buckets into a drain guarantees a serious problem: those materials set inside the pipe and can no longer be flushed out with pressurised water. It's one of the few situations where a domestic blockage ends in replacing a section of pipe.

The holiday rental case

In Mallorca there's an added factor. In a holiday let, whoever uses the drains changes every week and has no way of knowing what that particular installation tolerates: whether the property has a septic tank, whether the stacks are old, whether the village drainage was already stretched. That's why blockages in villas and tourist apartments concentrate in July and August, when peak occupancy and guest unfamiliarity coincide.

The most effective measure costs nothing: a short, clear notice in the bathroom and the kitchen, in your guests' languages, saying that only toilet paper goes down the toilet and that cooking oil doesn't go down the sink. It works better than any product, and it avoids the emergency call with the house full.

What an avoidable blockage costs

It's worth putting the cost in perspective. A preventive clean is a scheduled job, in normal hours, at a predictable price. A declared blockage is an emergency: you pay for the immediate call-out, often outside working hours, and you add whatever damage it caused around it — wastewater backing up on a ground floor, damp in a partition wall, ruined kitchen units or a cancelled booking.

At Tuberías y Aljibes we've spent more than fourteen years unblocking drains across the island, from flats in central Palma to country properties and villas, and after thousands of jobs the conclusion is always the same: most of the emergencies we attend could have been avoided with two habits and a drain strainer. If your drains are already running slow, that's the moment to have them looked at, not when they stop draining altogether. We go into more detail in why you shouldn't put off pipe cleaning.