Most blocked drains are not bad luck. They are caused by everyday habits, and most of them can be avoided. The Drain 247 team clears blockages across Watford, Hertfordshire and North West London every day. These are the ten causes we see most often, with simple ways to prevent each one.
Need a drainage engineer? Call Drain 247 on 0208 387 5591. Answered 24/7, no call-out fee, and the price is agreed before we start. Blocked now? See drain unblocking in Watford or, for a blocked soil pipe, blocked soil stacks.
The Scale of the Problem
Water UK says around 300,000 sewer blockages happen in the UK every year, and more than 3,000 homes are flooded by blockages every year. Thames Water says 60% of sewer flooding incidents are caused by sewer abuse, meaning things put down toilets and sinks that should have gone in the bin.
The 10 Most Common Causes of Blocked Drains
1. Wet Wipes
Wipes are the number one cause. Water UK says 94% of blockages are caused by wet wipes. They do not break down like toilet paper, even when the packet says “flushable”. Prevent it: keep a lidded bin in every bathroom.
2. Cooking Fat, Oil and Grease
Fat sets hard as it cools and coats the inside of the pipe. Thames Water says fats, oils and grease cause 28% of the blockages on its network. Prevent it: let fat cool and scrape it into the bin. Read more in fatbergs and your home drains.
3. Food Scraps
Rice, pasta, coffee grounds and peelings collect in the trap and the drain beyond. Prevent it: use a sink strainer and scrape plates into the food waste bin.
4. Hair and Soap
Hair binds with soap scum in shower and bath wastes. Prevent it: fit a hair catcher and clear the plughole regularly.
5. Sanitary Products, Cotton Buds and Nappies
These swell and snag in pipes. Prevent it: only flush the three Ps: pee, poo and toilet paper.
6. Too Much Toilet Paper
Toilet paper is designed to break down, but large amounts in one flush can still block a toilet or a drain with a poor fall. Prevent it: flush part-way through if you are using a lot.
7. Leaves, Soil and Garden Debris
Outside gullies and drains collect leaves, moss and silt, especially in autumn. Prevent it: clear the gully grids regularly and fit leaf guards to gutters. See our guide to a blocked outside drain.
8. Tree Roots
Roots find their way into old clay pipes through tiny cracks and joints, then grow and catch debris. Prevent it: plant trees away from drain runs. If roots are already in, they need cutting out. See tree roots in drains.
9. Limescale and Urine Scale
In hard-water areas such as Hertfordshire, scale gradually narrows pipes and soil stacks. Prevent it: have recurring slow drains checked. Scale is removed by descaling.
10. Damaged or Badly Laid Pipes
Cracked, sunken or displaced pipes, and drains laid with too little fall, catch debris over and over again. Prevent it: if the same drain keeps blocking, book a CCTV drain survey to find out why. See also drainage gradients and falls.
Early Warning Signs
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Water draining slowly from sinks, baths or showers.
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Gurgling noises from plugholes or the toilet.
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Bad smells from drains or outside gullies.
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The toilet water rising higher than usual when flushed.
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Water pooling around an outside drain.
Catching a blockage early is quicker and cheaper. Our guide on how to unblock a drain explains what you can safely try yourself.
Frequently Asked Questions
What Is the Most Common Cause of a Blocked Drain?
Wet wipes, followed closely by fat, oil and grease. Together they cause most household blockages.
Can I Use Chemical Drain Cleaner to Prevent Blockages?
We do not recommend it for regular use. Chemicals can damage older pipes and rarely clear fat or wipes. Prevention is better: keep these things out of the drain.
Who Is Responsible for Clearing a Blocked Drain?
Drains that serve only your home are usually your responsibility up to the property boundary. Shared drains and public sewers are usually the water company’s. See drainage problem: who is responsible?
How Much Does It Cost to Clear a Blocked Drain?
Our prices start from £90 for manual clearance, £120 for jetting and £165 for mechanical cutting. Fixed price quoted upfront before we start, no hidden extras. No call-out fee. See drain unblocking.
Drain Blocked Now?
We are available 24 hours a day across Watford, St Albans, Harrow and the rest of our areas served. Call 0208 387 5591.
Related reading: the five most common drainage problems in UK homes.
