By Show Me Step by StepPublished Updated
Based on a video by Home Repair Tutor.
Chemical drain cleaner is a temporary fix that eats your pipes and makes the plumber's job worse if it comes to that. The actual fix is to open the P-trap, pull the blockage out, and put it back. Twenty minutes, no specialist tools.
Jeff from Home Repair Tutor walks through the whole job, including how the pipework under your sink is put together and where clogs really form.
The P-trap is the U-bend under the sink. It holds a plug of standing water on purpose, which is what stops sewer gas coming up into the room. It is also the low point, so anything heavier than water settles there.
In a bathroom sink the blockage is usually hair bound up with soap scum, sitting on the pop-up stopper rather than in the trap itself. In a kitchen sink it is congealed fat with coffee grounds and food in it. Both clear by hand once you can reach them.
Put a bucket underneath. The trap is full of water and it is coming out, all of it, the moment the nut loosens. Lay a towel down too.
Most modern traps have plastic slip nuts you can undo by hand. Older metal ones need channel-lock pliers, and if the nut is corroded solid, that is the point to consider whether the whole trap wants replacing rather than fighting.
On a bathroom sink, the pop-up stopper is attached to a pivot rod that goes through the back of the drain body. Unscrew the retaining nut, pull the rod out, and the stopper lifts straight up with whatever is wrapped around it. This is usually the entire problem.
A zip-it is a barbed plastic strip that costs a couple of dollars. Push it down the drain, twist, pull, and it drags hair out. Disposable, and it solves most bathroom clogs without opening anything at all.
A small hand auger, or drum snake, reaches into the pipe going back into the wall for anything further along. Feed it in, crank, and work slowly. Forcing it just packs the blockage tighter.
Check the washers are seated and facing the right way before tightening, and hand-tighten the slip nuts plus about a quarter turn. Overtightening cracks plastic nuts, which turns a clog into a leak.
Run the tap and watch the joints for a full minute. A slow drip shows up late.
A drain screen catches hair before it gets in. Never pour cooking fat down the kitchen sink, even chasing it with hot water, because it congeals as soon as it hits the cool trap. Monthly boiling water helps kitchen drains and does nothing for hair clogs.
If the sink drains but the tap drips, that is a leaky faucet, a different job with different parts. For a blocked toilet, plunging technique matters more than force, and a running toilet is usually a $5 flapper.
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The curved pipe under your sink is called the P-trap. It holds a small amount of standing water that blocks sewer gas from coming back into your bathroom. Most sink clogs build up in three places: inside the P-trap itself, around the pop-up stopper rod, and in the pipe that goes into the wall.
Understanding the layout makes the rest of the job straightforward.
Put a bucket or container directly under the P-trap before you touch anything. Loosen the slip nut at the top of the curved section by hand. If it will not budge, use channel lock pliers. Then loosen the bottom nut. Water will pour out as you remove it.
Pull the whole P-trap off once it drains. Tap it out into your bucket. It will be full of buildup.
On the back of the drain pipe, there is a nut holding a small pivot arm in place. Loosen that nut with pliers and pull the arm out. It will be coated in goop. With the arm removed, pull the pop-up stopper straight up and out of the drain.
Hair and buildup collect on the pivot arm and stopper constantly. This is often the main cause of a slow drain.
Push a zip-it tool (a cheap barbed plastic strip) down into the drain opening from the top of the sink. Pull it back out slowly. The barbs grab hair and gunk on the way up. For deeper clogs, use a drain auger. Feed the cable in until you hit resistance, lock it, and spin to break through.
You can also push a paper towel through the drain and use the snake to push it out the bottom. It cleans the pipe walls on the way through.
With the P-trap off, you have direct access to the pipe going into the wall. Push your zip-it or auger into that pipe as far as it will go. Spin the auger when you hit something solid. Pull it back out and check what came with it.
This is where deeper clogs hide, especially in older homes. While you have it apart, you might as well clear this pipe too.
Before reassembly, clean every piece. Push a folded paper towel through the gooseneck pipe like floss to wipe the inside walls. Clean the pop-up stopper and pivot arm with paper towels. Rinse the P-trap out completely.
Everything should be clear of buildup before it goes back on. Otherwise you are just reinstalling a partial clog.
Put the gooseneck back into the wall pipe. Position the P-trap and hand-tighten both slip nuts, then snug them one quarter turn with channel locks. Reinstall the pivot arm into the drain and tighten its nut.
Turn the water on and let it run for a full minute. Check every connection for drips. If anything leaks, tighten that nut another quarter turn.
Tip
Put a drain hair catcher over the drain opening going forward. A two-dollar screen catches most of the hair before it goes down the drain and prevents clogs from forming.
Keep going
How to Replace a Toilet Fill Valve
How to Unclog a Sink the Right Way
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Question 1 of 5
What does the P-trap actually do?
Quick reference
5 questions, answers, and one-line explanations. Tap to expand.
1.What does the P-trap actually do?
Answer: Block sewer gas
Holds a small amount of standing water that blocks sewer gas from coming back into your bathroom.
2.Why not use chemical drain cleaners?
Answer: Damage pipes over time
Chemical cleaners are a temporary fix that can damage pipes over time. Take the P-trap apart instead.
3.Most common cause of slow bathroom sink drain?
Answer: Hair on pop-up stopper
Hair and buildup collect on the pivot arm and stopper constantly. Often the main cause - check there first.
4.Cheap tool with barbed plastic strip?
Answer: Zip-It tool
Push into drain from top, pull back slowly. Barbs grab hair and gunk on the way up.
5.Reassembly torque on the slip nuts?
Answer: Hand + quarter turn
Hand-tighten, then snug a quarter turn with channel locks. Over-tightening cracks the plastic threads.
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