If you are standing over a sink full of dirty water, or a toilet that will not flush, you probably want to know whether you can fix it yourself. Often you can. A single slow sink or bath is usually a blockage close to the plughole or in the trap. But if several fittings are backing up, the problem is further down the drain, and no amount of bicarbonate of soda will shift it. This guide from the Drain 247 team shows you how to tell the difference, the DIY methods that actually work, and what not to do.
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. If you would rather not do it yourself, see our drain unblocking service or blocked drains in Watford.
Step 1: Check Which Kind of Blockage You Have
Green Light: Try DIY
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The water is draining, just slowly.
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Only one sink, basin, bath or shower is affected.
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There are no bad smells or gurgling sounds from other fittings.
Red Light: Stop and Call a Professional
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More than one fitting is blocked. For example, you flush the toilet and the shower tray fills up.
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The outside manhole or gully is overflowing.
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You can smell sewage inside the house.
Red-light signs mean the blockage is in the main drain. Chemicals and cheap rods are unlikely to reach it and can make it worse. Book drain unblocking instead.
Step 2: Check Whose Drain It Is
Thames Water, which runs the sewers in London and much of Hertfordshire, says a blockage may be its responsibility if the problem is outside your property boundary or more than one property is affected. If your neighbours have the same problem, report it to the water company before you pay anyone. Inside your boundary, drains that serve only your home are your responsibility. See drainage problem: who is responsible?
Step 3: the DIY Methods That Actually Work
Method 1: Hot Water, Bicarbonate of Soda and Vinegar (for Grease and Soap)
Best for: kitchen sinks and slow showers.
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Pour a kettle of hot water (not boiling if you have plastic pipes or are pouring into a toilet) down the plughole.
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Add a cup of bicarbonate of soda, then a cup of white vinegar.
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Put the plug in straight away so the fizz pushes down into the pipe.
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Wait 10 minutes, then flush through with more hot water.
This loosens light soap and grease films. It will not clear a pipe packed with fat or wipes.
Method 2: the Plunger, Used Properly
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Block the overflow hole with a wet cloth first. Otherwise the air escapes through the overflow instead of pushing on the blockage.
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Make sure there is enough water to cover the cup of the plunger.
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Push gently to remove the air, then pull up sharply. It is the suction that clears the drain.
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For toilets, use a flanged toilet plunger rather than a sink plunger.
Method 3: Clean the Trap (U-Bend)
If plunging does not work, the blockage is likely food, hair or a lost item caught in the trap under the sink.
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Put a bucket under the trap.
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Unscrew the plastic nuts by hand.
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Clean out the trap and check the pipe beyond it.
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Refit it carefully without cross-threading the nuts, then run the tap and check for leaks.
Method 4: Clear Hair from Bath and Shower Waste
Most slow showers and baths are blocked by hair close to the plughole. Remove the waste cover and pull the hair out with a plastic drain-cleaning strip or gloved fingers.
Method 5: Rod an Outside Drain (Only If You Are Confident)
If the blockage is in an outside drain and you have proper drain rods, you can try rodding from the manhole. Our guide on how to use drain rods explains how to do it safely. Always turn the rods clockwise.
What Not to Do
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Do not twist cheap rods anticlockwise. They unscrew, and we regularly get called to retrieve rods stuck in drains.
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Be careful with caustic or acid drain cleaners. They produce heat, can damage plastic pipes and seals, and are dangerous if the water splashes back. They rarely clear fat or wipes anyway.
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Do not keep flushing a blocked toilet. Each flush adds water that has nowhere to go.
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Do not climb into manholes or chambers. Lift the cover and look, but do not go in.
Why Drains Block in the First Place
Most household blockages are caused by things that should never go down the drain. Water UK says 94% of blockages are caused by wet wipes, and Thames Water says fats, oils and grease cause 28% of the blockages on its network. Bin wipes and cooking fat, and only flush pee, poo and toilet paper. Our guide why do drains get blocked? covers the other common causes.
When DIY Has Not Worked
If you have tried the methods above and the water still will not go down, the blockage is further along the pipe or caused by something hard, such as scale, roots or a collapsed section. Stop there, because pushing harder can compact it. Our engineers carry rods, a high-pressure jetter and a cutting head on every visit. 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.
Frequently Asked Questions
Does Bicarbonate of Soda and Vinegar Really Unblock a Drain?
It can help with light soap and grease films in sinks and showers. It will not clear a solid blockage of fat, wipes or roots.
Is It Safe to Pour Boiling Water Down a Drain?
Hot tap water or water from a kettle that has cooled a little is safer. Boiling water can soften plastic pipe joints and can crack a ceramic toilet pan.
How Do I Know If the Blockage Is in the Main Drain?
If more than one fitting is slow, water comes up in the bath or shower when you flush, or the outside manhole is full, the blockage is in the main drain.
Need Help Now?
We unblock drains 24 hours a day across Watford, St Albans, Harrow, North West London and the rest of our areas served. Call 0208 387 5591 or book online.
