Most people blame hair or cooking grease when a drain starts running slow. And sure — those don't help. But the calls we get most often involve something the homeowner genuinely didn't see coming. Here are five things that cause blocked drains far more often than people realise, and what to do about each of them.

1. Coffee Grounds

This surprises almost everyone. Coffee grounds feel small and fine, so rinsing them down the kitchen sink seems harmless. It isn't.

Unlike most organic matter, coffee grounds don't dissolve in water. They're heavy, they clump together when wet, and they settle at the lowest point in your pipe — typically inside the U-bend beneath your sink. Once they're sitting there, they act like a net: every bit of grease, soap scum and food debris that follows sticks to them, and the blockage grows quickly from there.

Plumbers consistently rank coffee grounds among the top causes of kitchen sink blockages. The fix is simple: tip them into the bin or compost. Takes five seconds. Saves you a call-out.

2. "Flushable" Wipes

The label says flushable. The label is wrong.

Unlike toilet paper, which is specifically designed to break down rapidly in water, wet wipes — even ones marketed as flushable — are reinforced with fibres that don't disintegrate in your pipes or the sewer system. Water UK reports 300,000 sewer blockages per year in the United Kingdom alone, with wipes named as a leading cause. The pattern is the same across Europe.

What actually happens when you flush a wipe: it travels through your pipes, snags on any rough spot or existing debris, and starts collecting everything that comes after it. Combined with fats and grease, they form what engineers call "fatbergs" — solid masses that can block an entire pipe. Thames Water alone clears over 75,000 blockages annually at a cost of around £40 million, with wipes a major contributing factor.

Bin them. All of them. Regardless of what the packaging says.

3. Rice and Pasta

You'd think a few stray grains of rice down the plughole would be no big deal. The problem is what happens next.

Rice, pasta and other starchy foods expand with water, creating a glue-like substance that clings to the inside of pipes. Raw rice absorbs moisture and swells. Cooked pasta continues to absorb water long after it's been plated. Both sink to the bottom of your drain pipe and stay there, building up over time into a dense, sticky mass that narrows the pipe and slows everything behind it.

This is one of the reasons kitchen drains in homes with a lot of cooking tend to block more frequently than others. Use a sink strainer to catch food scraps before they make it into the pipe, and scrape plates into the bin rather than rinsing them straight under the tap.

4. Liquid Soap in Large Amounts

This one genuinely catches people off guard. Soap is supposed to clean things, including your pipes. So how does it cause a blockage?

On its own, liquid soap draining away is fine. The issue is volume and what it combines with. When used in large amounts, liquid soap goes down the drain and clumps together with hair and other debris, forming a thick, gooey mass that builds up inside the pipe. In hard water areas — which includes most of the Netherlands — soap also reacts with the calcium in the water to form soap scum: a chalky residue that sticks to pipe walls and accumulates over time.

This shows up most often in bathroom sinks and showers. If your bathroom sink is running slow and you can't see a hair blockage, soap scum build-up is a very likely culprit.

5. Eggshells

Eggshells seem too light and brittle to cause real trouble. They're not.

Eggshells don't decompose quickly and can stick to the sides of pipes, creating a layer that traps everything else passing through. Crushed eggshell creates a granular, gritty waste that combines with grease and coffee grounds to form a particularly stubborn type of blockage — harder to shift than a simple hair clog and often requiring professional equipment to clear properly.

The bin is the right destination for eggshells. Every time.

When It's Already Blocked

If your drain is running slow, that's an early warning — a partial blockage that's growing. Don't wait until it stops entirely.

Avoid chemical drain cleaners. They're harsh on older pipes and rarely solve the underlying problem; they typically just dissolve the surface layer of a blockage and let it reform further along. A professional drain clear uses mechanical equipment to remove the blockage completely, not just push it down the line.

Your English Plumber covers drain unblocking across the Netherlands — Amsterdam, Rotterdam, Utrecht, Den Haag, Haarlem, Leiden and more — from €129 including VAT , available 24/7, on-site within 2 hours.

Drain running slow? Call 06-24356980 or WhatsApp us before it stops completely.