What can go down the toilet? And what definitely can't

A toilet seems like a place where everything can disappear. Press the button and it's gone. But behind the bowl begins a drain pipe with bends, connections and sometimes a long horizontal section before the water reaches the soil stack or sewer. Anything that doesn't break down quickly can get caught along the way.

What can go down the toilet?

• Urine and faeces. That's what the system is designed for.
• Toilet paper. Toilet paper is designed to break down quickly in water. Use a reasonable amount at a time and if there's a lot of paper, flush twice.

That's it. Anything not on this list belongs in the bin or must be disposed of another way.

What should not go down the toilet?

• Wet wipes, even if labelled "flushable". Wet wipes, baby wipes and make-up wipes break down far more slowly in water than toilet paper. Even the variants sold as flushable often remain intact in practice for a long time. They catch on each other and, together with grease, form solid clumps.
• Kitchen roll and tissues. Kitchen paper and tissues are specifically made to stay strong when wet. As a result, they don't break down well in the drain.
• Tampons, panty liners and sanitary towels. These are made to absorb moisture and swell in water. They are a well-known cause of blockages.
• Cotton buds and cotton pads. Cotton buds are stiff and get stuck sideways in a bend. Other debris collects behind them.
• Hair. Hair does not dissolve and together with paper forms a kind of net in which everything gets caught.
• Fat and frying oil. Fat solidifies in the pipe and turns other waste into a tough mass. This can create large fat clumps in the sewer.
• Medicines. Medicine residues do not belong in wastewater, because water treatment cannot always remove them completely. Return them to the pharmacy or follow your municipality's rules.
• Cat litter. Much cat litter clumps precisely on contact with moisture. In the drain it becomes a hard, cement-like blockage. Even litter sold as flushable can cause problems.
• Food scraps. Leftover food, rice and pasta seem harmless, but they expand in water, attract vermin in the sewer and can cause blockages in combination with grease.
• Other items. Think of condoms, nappies, plasters, dental floss, cigarette butts, paint and cleaning wipes. These don't belong in the toilet either.

What happens in the drain and the sewer?

Directly behind the toilet is a short drain with one or more bends. If something gets caught there, you'll notice quickly: the bowl fills up high after flushing and drains very slowly. This is the simplest form of blockage.

It becomes more difficult when the object gets further. In an apartment block, the drain connects to a shared soil stack. Wipes from multiple flats come together there. If a blockage forms there, residents on the lower floors notice it most: their toilet or shower overflows. Read more about this in the article on a blocked soil stack.

In the sewer under or outside the property, wipes can accumulate at connections, subsidence or places where roots have grown into the pipe. At grinders and pumps in the public sewer, wipes also cause breakdowns. So the problem does not stop at the front door.

Signs that something is stuck in the drain

• The toilet rises higher than normal after flushing.
• The water drains away slowly or makes gurgling sounds.
• The toilet gurgles when you let water drain elsewhere. See also drain or toilet gurgles.
• There's a sewer smell in the toilet or bathroom.

How to prevent a blocked toilet

• Put a waste bin in the toilet. Those without a bin are more likely to flush something that doesn't belong. A small bin with a lid next to the toilet really helps.
• Always put wet wipes in the bin, even if the packaging says they're flushable.
• Use a reasonable amount of toilet paper and flush in between if in doubt.
• Tell housemates, children and guests. A small notice in the toilet of a holiday home or office can save a lot of trouble.
• Never pour fat or oil down the toilet or kitchen sink. Let it solidify and put it in the general waste, or dispose of it according to your municipality's rules.
• Return medicines to the pharmacy or follow your municipality's waste rules.
• Watch out for a flush button that doesn't work properly. If the toilet flushes too weakly, paper is more likely to remain. Have this checked.

Is the toilet blocked after all?

Don't keep flushing repeatedly when the water is already high; the bowl may overflow. First try a plunger with a flange that seals well in the toilet's drain opening. Don't use chemical drain cleaner or boiling water: the latter can crack the porcelain. The article toilet blocked, how to fix it contains a complete step-by-step plan. If that doesn't work, you can call us for toilet unblocking.

Want to know which products work and which don't? Read drain unblockers: what really works. More tips for the rest of the house can be found in preventing blockages.