10 Common Causes for Blocked Drains & how to avoid them

A blocked drain is probably one of the most routine plumbing problems there can be. To help you work out what’s wrong, here are ten of the most common causes for blocked drains. Plus, we’ll also explain how to fix them and what you can do to avoid them.

Common causes for blocked drains


We’ve all probably lived or live with someone who leaves the drain in the bath or shower in a bad state. Hair is an extremely common reason for a blocked drain, and will restrict the flow of water down the plughole before stopping it completely, if nothing is done to stop it.

You can prevent hair from blocking bathroom drains by fitting a drain cover or drain protector. A drain auger or plumbing snake may help you remove clumps of hair close to the plughole, but blockages further down the pipe may require the use of a plunger.


If there were a competition for the most common causes for blocked drains, fat would probably win the trophy. It’s the main component of fatbergs – the enormous masses of congealed grease that block public sewers. It’s so bad because when it cools, it solidifies and hardens.

After cooking a big meal, it’s easy to be lazy when washing up. But the bottom line is that if you don’t want a blocked kitchen sink, don’t let fat, oil and grease go down there. If fat is the culprit, a chemical drain unblocker may solve the problem.

Coffee grounds

Believe it or not, coffee grounds are just as problematic as fat – and for the same reason. They too will solidify and harden, narrowing the drain before blocking it completely.

Like fat, the most effective solution is simply not to let any coffee grounds go down the drain when you clean your coffee machine’s parts.

Food particles

While some foods may not change consistency, they can still be enough to cause a problem. Particles of food that go down the plughole can cause an obstruction if they build up, or if they settle in the U-bend. So, make sure you are scraping bits of leftover food into the bin. You can prevent food particles from causing a blocked kitchen sink by fitting a plughole strainer.

Wet wipes

While many wet wipe manufacturers insists that their products can be safely flushed down the loo, a lot of water authorities do not share this opinion. In fact, wet wipes are the key element in fatbergs. Without them, fatbergs would not be able to form.

Fortunately, standards are changing. The industry is working to make sure that wet wipes will no longer be one of the common causes for blocked drains. Look for wet wipes with the ‘Fine to Flush’ certification. This certifies that the wet wipes in question will disintegrate properly in the sewer.


Contraceptives, tampons, sanitary towels, cotton wool buds, etc. are not designed to disintegrate in the sewer, and should never be flushed down the toilet. Throw them away with the normal household waste. You can encourage that they are disposed of this way by putting a small bin in the bathroom.


Leaves, weeds, and garden debris are extremely common causes for blocked drains, particularly in the autumn. Make sure that drain gullies are protected with plastic covers or mesh screens.

Inanimate objects

Foreign objects can easily make their way into the sewer if there are children in the household. Curious youngsters who like to play with water may try to flush objects down the toilet. Of course, the solution is to educate them. Playing with the toilet is not hygienic, and it may not be so appealing to them once they realise that flushing their favourite toy could mean it’s gone forever.

Damage to sewer pipes

Damage to sewer pipes can easily result in blocked drains. One of the most common causes for this is tree roots.

Poor installation

A poor installation may result in blocked drains. For example, if the pipes are too small, they may be prone to blocking.