There’s a particular sound that tells you something’s wrong before anything has actually overflowed. A gurgle from the kitchen sink when the washing machine empties. A toilet that hesitates before it flushes properly. Water sitting in the shower tray a bit longer than it should.
Most people ignore it for a week or two. Understandable, but blockages don’t clear themselves, and the gap between “slow drain” and “sewage on the utility room floor” is usually shorter than you’d like.
If you’re wondering how to unblock a drain, the good news is that a fair proportion of blockages are genuinely a DIY job. You don’t need a plumber for every slow-running sink, and we’d rather tell you that honestly than charge you for something you could have sorted in twenty minutes with a plunger.
The rest of them aren’t, and knowing the difference is what this guide is for.
If you’re already past the point of experimenting and want someone out, you can get in touch with Lime Heating here. If you’d rather have a go yourself first, read on.
<— Image with alt text (water draining slowly in a kitchen sink) —>
How to unblock a drain: a plumber’s guide
Every blockage is a variation on the same theme. Something has gone into the pipe that shouldn’t have, and it’s caught on something else that went in earlier.
Where it’s stuck determines how you tackle it, which is why “how to unblock a drain” doesn’t have one single answer. Clearing a shower trap is a completely different job to clearing a blocked gully outside.
We’re going to be covering:
- How do I know if I have a blocked drain?
- What causes blocked drains?
- How to unblock a sink drain
- How to unblock a shower drain
- How to unblock a drain outside
- When to call a professional
- How to keep your drains clear
How do I know if I have a blocked drain?
Drains give you plenty of warning. The trick is recognising it.
Gurgling is usually the first sign. Air is being forced back through the water in the trap because it can’t get past an obstruction further down the pipe. If your sink burbles when the washing machine drains, that’s not a quirk of the plumbing, it’s a message.
Slow drainage is the next stage. Water that used to disappear now sits and thinks about it. Then come the smells: stagnant water and trapped waste don’t stay odourless for long.
Water rising where it shouldn’t is the serious one. If flushing the toilet raises the water level in the shower tray, or emptying the bath brings water up through a downstairs drain, the blockage is somewhere shared rather than in one individual fitting.
That last symptom matters, because it changes who’s responsible for fixing it.
If only one fitting is affected, the problem is almost certainly in that fitting’s own waste pipe and it’s yours to sort. If several are affected at once, the blockage is in the shared drain or the sewer, and depending on exactly where it sits, it may be your water company’s job rather than yours. Anglian Water covers Milton Keynes and most of the surrounding area, and their guide to sewer pipe responsibility explains where the boundary falls.
Worth checking before you spend money on a private call-out.
<— Image with alt text (open drain cover showing standing water in a gully) —>
What causes blocked drains?
Almost every blockage we attend comes down to one of four things.
Fat, oil and grease. The single biggest culprit in kitchen waste pipes. It goes down the sink as a warm liquid, cools in the pipe, and sets on the walls like candle wax. Every subsequent bit of food waste sticks to it. Water UK’s work on fatbergs shows how quickly this scales up once it reaches the sewers.
Pour it into an old jar or tin, let it set, and bin it. It takes ten seconds and saves an enormous amount of grief.
Wet wipes and sanitary products. Nothing goes down the toilet except the three Ps: pee, poo and paper. Wipes labelled “flushable” are the worst offenders because people believe the label. They don’t break down like toilet paper does, and the Bin the Wipe campaign exists precisely because of the damage they cause.
Hair and soap scum. The bathroom equivalent. Hair catches in the trap, soap residue binds it together, and within a few months you’ve got a solid plug.
Leaves, silt and roots outside. External gullies fill with debris, particularly in autumn. Tree roots are a longer-term problem, working into pipe joints looking for moisture and eventually cracking them open. If your outside drain blocks repeatedly in the same spot, roots are a strong suspect and no amount of rodding will fix it permanently.
<— Image with alt text (plunger being used on a kitchen sink) —>
How to unblock a sink drain
Start with the simplest option and work up. Most kitchen and bathroom sinks clear without anything more than a plunger.
- Try boiling water first. For a slow-running kitchen sink where grease is the likely cause, a kettle of boiling water poured straight down the plughole will often soften the blockage enough to shift it. Don’t do this if you have plastic waste pipes and the water is genuinely at a rolling boil — very hot from the tap is safer.
- Then plunge it. Block the overflow with a damp cloth first, or you’ll just push air out of it rather than pressure down the pipe. Cover the plughole with the plunger, make sure there’s enough water in the basin to seal it, and work it firmly for twenty or thirty seconds. Sharp, repeated pressure does more than one heroic shove.
- Clean the trap. If plunging fails, the blockage is probably sitting in the U-bend under the sink. Put a bucket underneath, unscrew the trap by hand, and clear out what’s inside. It’s unpleasant but it’s not difficult, and it solves the problem more often than anything else on this list.
- A drain snake for anything further. If the trap was clear, the obstruction is further along the waste pipe. A cheap drain snake fed through will usually reach it.
A word on chemical drain cleaners: we’d rather you didn’t. They can corrode older pipework, they’re hazardous to handle, and if they don’t clear the blockage you’ve now got a pipe full of caustic liquid that any plumber will have to deal with. A plunger and a bucket will get you further.
<— Image with alt text (hair and soap residue removed from a shower trap) —>
How to unblock a shower drain
Showers are nearly always hair, and the blockage is nearly always within reach.
Lift the grate or cover first — most unclip or unscrew with a small screwdriver. What’s underneath is usually the problem, sitting in the trap just below.
Pull it out by hand with gloves on, or use a length of wire with a small hook bent into the end. Drain claws cost a couple of pounds and are the right tool for this, largely because they grip hair rather than pushing it further down.
Once you’ve cleared what you can reach, run the hot tap for a minute or two to flush the softened soap residue through. If it’s draining freely, you’re done.
If it isn’t, plunge it the same way you would a sink. And if that still doesn’t shift it, the blockage is beyond the trap and it’s time to stop guessing.
For a fuller picture of where the sensible DIY line sits across plumbing generally, we’ve covered when to DIY and when to call a plumber in a previous article.
<— Image with alt text (drain rods being fed into an outside manhole) —>
How to unblock a drain outside
External drains are a bigger job, and the first thing to say is that they carry a genuine health risk. Standing wastewater harbours bacteria you don’t want on your hands or in your eyes.
Get the right kit. Waterproofs, heavy gloves, and eye protection at minimum. You’ll also want a bucket, a hose, and a set of drain rods. Rods are widely available from DIY shops and don’t cost much.
Work out what you’re dealing with. Lift the drain cover and look. Can you see the blockage? Can you tell what it is — leaves and silt, or something solid? Can you reach it?
This matters more than anything else you’ll do. A build-up of silt and debris will break apart with a bit of persistence. Something solid and wedged is a different proposition, and knowing which one you’ve got tells you whether to carry on or stop.
Clear what you can reach by hand. Not the highlight of anyone’s weekend, but removing the loose material into a bucket first means there’s less to push through when you start rodding.
Then rod the rest. Find the nearest manhole to the blockage and lift the cover. Feed the rods in, working them into the obstruction and turning them clockwise as you go. Turning them the other way can unscrew a section and leave it down there, which turns a bad afternoon into a worse one.
You’ll feel the resistance ease as the blockage breaks up. Flush it through with the hose, and use the water level as a guide if you can’t see what’s happening. When the water runs away freely, put the cover back on.
If you rod for a while and nothing changes, stop. A blockage that won’t move usually means a collapsed pipe, root ingress, or something that needs a camera survey rather than more force. Anglian Water’s advice on blocked pipes is a useful reference point for working out whether the problem is even yours.
<— Image with alt text (Lime Heating plumber inspecting drainage outside a property) —>
When to call a professional
Call someone out when:
- You’ve tried the above and the blockage hasn’t moved
- More than one fitting is backing up at the same time
- Wastewater is coming back up into the house
- The same drain blocks repeatedly, which suggests a structural problem rather than debris
- There’s a smell of sewage inside the property
- You can’t safely reach or access the drain
Repeated blockages in the same place are the one people most often ignore. Clearing it each time treats the symptom while whatever’s causing it — a partial collapse, a displaced joint, roots — carries on getting worse.
Our plumbers in Milton Keynes deal with drainage across the city and the surrounding area, and we’ll tell you honestly whether it’s a clear-and-go job or something that needs investigating properly.
If wastewater is actually coming into the property, don’t wait for a convenient appointment. Our emergency plumbers in Milton Keynes are available for exactly this, and the damage gets more expensive the longer it sits.
How to keep your drains clear
Most of what we’ve described is avoidable. A few habits will prevent the majority of household blockages:
- Fat, oil and grease into a container and then the bin, never down the sink
- Only the three Ps down the toilet — everything else goes in the bin, wipes included
- A cheap plughole strainer in the kitchen sink and shower catches food waste and hair before it gets into the pipe
- Clear leaves and debris out of external gullies a few times a year, particularly through autumn
- Never pour paint, motor oil or solvents into any drain — a lot of surface water drains run straight to rivers
None of it is complicated, and it’s considerably cheaper than a call-out.
Need a hand with a blocked drain?
If you’ve had a go and the drain still isn’t running, or you’d rather not spend Saturday morning with a set of rods and a bucket, we can help.
Lime Heating covers Milton Keynes, Northampton, Bedford, Buckingham, Leighton Buzzard and the surrounding areas, and our plumbers handle everything from a stubborn sink trap to full drainage investigations. We’ll tell you what’s actually wrong, what it’ll cost to fix, and whether it’s a job for us or one for your water company.
Give us a call on 01908 904 407 or make an enquiry here, and we’ll get someone out to you.
Don’t be a lemon — call Lime!
