How to Unclog a Drain

Updated August 2026 · Home Project Resources

Start mechanical, not chemical. A plunger, a hand snake, or twenty minutes with the P-trap under the sink clears the large majority of household clogs, and those three methods together cost less than the trip charge on a single plumber visit, in tools you'll own forever. Chemical drain cleaner is the option most likely to make things worse.

That order matters because mechanical methods remove the clog. Chemicals try to dissolve it, usually fail on a full blockage, and leave a pipe full of caustic liquid sitting on your fittings. Work through the fixture-by-fixture table below, escalate one step at a time, and stop when the water runs.

Planning bathroom work while you're in there? Our tile calculator gives you square footage and box counts in seconds, and the bathroom remodel cost guide shows where the money actually goes if this clogged drain is the last straw.

Updated August 2026

A note on numbers. This page gives you methods, diagnostics, tool specs and the point at which a clog stops being a DIY job, not dollar figures. Plumbing labor rates, call-out policies and after-hours charges vary by market and by month, and we do not set any of them. Diagnose first, then get quotes on the work that is actually needed.

How to unclog a drain: the escalation order

Try these in sequence. Each step is cheap, and each one gets slightly more involved. Most people never get past step three.

1. Boiling or very hot water (skip on PVC and on toilets). Two quarts poured slowly in three stages, waiting a minute between pours.
2. Plunger. Cup plunger for sinks and tubs, flange plunger for toilets. Block the overflow first.
3. Baking soda and vinegar, then hot water. Modest, but genuinely useful on slow grease and soap film.
4. Hair zip tool for anything in a tub or shower. The cheapest item in this list, and it solves most bathroom clogs outright.
5. Hand drain snake (auger), 25 feet, hand crank. Inexpensive, and the last DIY step before you call someone.
6. Pull and clean the P-trap. No special tools needed on most plastic traps.
7. Closet auger for toilets specifically. Costs about the same as a hand snake and is not interchangeable with one.
8. Call a plumber if more than one fixture is affected, or if you're into a main line.

Skip straight to step 8 if you're seeing multiple slow drains, water backing up in one fixture when you use another, or gurgling. That is a different problem, and it's covered further down.

Method by fixture: what to try first, and what's next

Plunging, done properly

Most people plunge badly. Three fixes make a big difference.

Seal the second opening. A double bowl kitchen sink shares one drain line, so plunging one side just pushes water and air out the other. Have someone hold a wet rag hard over the other basin, or clamp a flat stopper on it. In a bathroom sink or a tub, the overflow opening does the same thing. Stuff a wet rag into it and hold it.

Get water in the bowl. A plunger moves water, not air, and water doesn't compress. You want two to three inches over the drain opening. If the fixture is dry, add water.

Push slowly on the first stroke, then go hard. The first push should be gentle to squeeze air out from under the cup without blowing water everywhere. After that, 15 to 20 firm strokes with the seal never breaking, then a sharp pull on the last one. The pull often does more than the pushes.

If a full 20 stroke cycle changes nothing, plunging is not going to work. Move on.

Cleaning a P-trap, step by step

The P-trap is the U-shaped bend under the sink. It holds a plug of water that blocks sewer gas, and it also catches every ring, screw, and clump of hair that goes down the drain. On a bathroom sink it is the answer more often than not.

Budget 20 minutes.

1. Put a bucket under the trap. Do this first. The trap holds about a cup of water, plus whatever is standing in the sink above it. Everyone who skips the bucket learns this once.
2. Turn off the faucet and tell everyone in the house not to use that sink. There's no pressurized supply line involved here, but water sent down an open drain lands on your floor. If you're also disturbing supply lines or the stopper linkage, close both supply stops under the sink, turn them clockwise until they stop.
3. Lay a towel in the cabinet. Plus a flashlight, propped where it lights the trap.
4. Loosen the two slip nuts by hand. One connects the trap to the tailpiece coming down from the sink, one to the trap arm going into the wall. Plastic nuts almost always turn by hand. If they're stiff, use large slip-joint pliers with light pressure, and wrap the nut in a rag so you don't crack it.
5. Lower the trap straight down into the bucket and let it drain.
6. Clean it out. An old toothbrush and a bottle brush. Rinse it in another sink or outside, not the one you just opened.
7. Check the trap arm going into the wall too. Reach in with the zip tool or a bent coat hanger. Gunk collects right at the entrance.
8. Inspect the washers. The tapered plastic or nylon washers should sit against the pipe with the cone pointing toward the nut. If one is cracked, flattened, or missing, replace it. A pack costs almost nothing and a bad washer is the single most common cause of a drip after this job.
9. Reassemble hand tight, then a quarter turn with pliers. Slip joints seal by compression, not by torque. Overtightening cracks plastic.
10. Run water for a full minute and put a dry paper towel under each joint. Come back in an hour and check again. Slow drips take time to show.

On chrome or brass traps, expect the nuts to be tight and the tubing to be thin. Support the trap while you turn, and be ready to replace the whole trap kit, which is cheap, if the metal is corroded through.

Hair clogs in tubs and showers

Almost every tub and shower clog is hair bound together with soap scum, sitting within the first 12 inches of the drain. You do not need a snake for this, and a snake often does worse than a hair tool because it punches through the mat instead of pulling it out.

Get a zip tool. It's a flexible plastic strip about 20 inches long with barbs down both edges, sold in an inexpensive two pack at any hardware store. Push it down, twist a half turn, pull it back up slowly. What comes out is unpleasant and completely diagnostic. Repeat until it comes up clean.

Then:

• Shower: unscrew the strainer first if it's a screw down type, or pry it up if it's a snap in. The mat is usually right there.
• Tub with a lift and turn stopper: unscrew the knob, lift the stopper out, and clean the crossbar underneath.
• Tub with a trip lever (the plate on the overflow): the linkage and plunger assembly pulls straight up out of the overflow after you remove the two screws on the plate. Hair collects on that assembly. Clean it and reinstall it in the same orientation.
• Bathroom sink with a pop-up: the horizontal pivot rod goes into the back of the drain body under the sink. Unscrew the retaining nut, pull the rod back, and the stopper lifts out. Hair wraps around the stopper's tail. This is a five minute fix with no tools.

Follow up with very hot water and a squirt of dish soap to cut the remaining soap film.

Toilet clogs: the plunger type matters

Using a cup plunger on a toilet is why people think plunging doesn't work.

Use a flange plunger. A cup plunger is a plain rubber dome, designed for the flat surface around a sink or tub drain. A flange plunger has a soft rubber sleeve that extends down from the cup, and that sleeve is what seats into the round toilet outlet and makes a real seal. A flange plunger costs a little more than a cup plunger and is worth every bit of it. Buy one and keep it in the bathroom.

Steps:

1. Shut the supply stop behind the toilet before your first plunge if the bowl is near the rim. Turn the oval handle clockwise until it stops. This prevents an overflow if a fill cycle triggers.
2. Get the water level right. You want enough water to submerge the plunger cup, not so much that it splashes over. Bail some out with a cup into a bucket if it's high, or add some if the bowl is nearly empty.
3. Seat the flange into the outlet and push down gently the first time. Air trapped under the cup will blow bowl water at your face otherwise.
4. Twelve to fifteen firm strokes, keeping the seal, finishing with a sharp pull.
5. Watch the water level. If it drops on its own, you've broken the clog. Open the supply and flush once, watching. If the bowl fills toward the rim, close the flapper by hand or shut the supply again immediately.

If two full plunging rounds fail, switch to a closet auger. It's a 3 to 6 foot cable inside a rigid tube with a protective vinyl boot on the bend. The boot is the point, because a plain drain snake will scratch the porcelain glaze permanently.

Put the boot into the outlet with the curve pointing into the trapway, crank the handle while pushing gently, and feel for the obstruction. When you hit it, either bore through it or hook it and withdraw. Pull the cable back slowly. Whatever caused the clog often comes back with it, and toys, dental floss wads, and wipes are the usual suspects.

If the auger reaches its full length and still finds resistance, or the clog keeps returning, the toilet may need to come off the flange so you can work from underneath. That's the point where our toilet installation guide covers the wax ring and reset properly, and also the point where many people are better off calling a plumber.

The honest truth about chemical drain cleaners

Chemical cleaner is the first thing most people reach for and the thing plumbers wish they wouldn't. Three real problems, none of them marketing spin.

They don't clear a full blockage. Caustic and acid cleaners work by contact. If the pipe is completely stopped, the product sits in the standing water above the clog, gets diluted, and never reaches the mass in a concentrated form. On a slow drain, they can dissolve some soap and grease film. On a solid clog, they mostly just sit there.

They can damage older pipes. Sodium hydroxide and sulfuric acid formulas generate real heat as they react. That heat can soften and deform PVC and ABS, especially at glued joints, and repeated use thins old galvanized steel and corrodes the rubber washers inside your trap and slip joints. Cast iron and older galvanized drain lines in homes built before the 1960s are the most vulnerable.

A drain full of cleaner is a hazard for the next person. This is the part nobody mentions. When the plumber arrives and pulls the trap, that caustic liquid comes out into their face and hands. If you have used a chemical cleaner and you're calling someone, tell them at the door, before they open anything. It is a basic courtesy and a real safety issue.

If you do use one, never mix products, never follow a caustic cleaner with an acid one, ventilate the room, wear eye protection and gloves, and never plunge a drain that has cleaner sitting in it.

Enzyme drain treatments are a different thing. They use bacteria and enzymes to eat organic buildup over hours, not minutes. They will not clear a blockage today, but as a monthly maintenance pour in a kitchen sink or a slow bathroom drain, they're safe for every pipe material and they genuinely help.

When it's not one fixture: main line and vent problems

Stop DIY work and call a plumber if you see any of these. They point at the shared drain or the vent stack, not at the fixture in front of you.

• More than one fixture draining slowly, especially on more than one floor.
• Using one fixture causes another to react. Running the washing machine backs water into the shower. Flushing the toilet makes the tub gurgle. Water rising in a floor drain when the laundry drains.
• Gurgling. A drain that gurgles is pulling air through the water in a trap because it can't get air from the vent. That's either a blocked vent stack or a partial main line blockage.
• Sewer smell in the house with no dry traps to explain it.
• The lowest fixture in the house backs up first. Basement floor drains and first floor toilets are the canaries.
• Any sewage backup at all. That's a same day call, not a Saturday project.

Why this is not DIY: a main line clog is typically 10 to 60 feet out, often tree roots at a joint or a collapsed section of clay pipe on older properties. Clearing it takes a powered drum machine or a hydro jetter, and diagnosing it properly takes a camera inspection. Renting a power auger and running it yourself is a genuine way to injure a wrist or drive a cable through a compromised pipe.

The services below are listed cheapest to most expensive, and the gaps between them are large. Knowing which one you actually need is most of what protects you on the phone.

Materials and labor are bundled in drain service, which is normal for the trade. Three questions get you a comparable quote from every shop you call: is the drain clearing charged as a flat rate or hourly, is the trip charge separate, and what happens to the price if the cable does not clear it. If a shop will not answer those on the phone, call the next one.

Worked example: a slow bathroom sink, start to finish

A bathroom sink that takes 90 seconds to drain a full basin. Here's an actual run through the escalation, with times and costs.

• Minute 0 to 3. Two quarts of hot tap water, poured in three stages. No change. Cost: nothing.
• Minute 3 to 8. Removed the pop-up stopper by loosening the pivot rod nut behind the drain body. Pulled a hair and toothpaste mass off the stopper tail. Basin now drains in about 40 seconds, better but still slow. Cost: nothing.
• Minute 8 to 14. Zip tool down the open drain, three passes, twisting a half turn each time. Two more clumps came up. Drain time down to 15 seconds. Cost: one two pack of zip tools.
• Minute 14 to 32. Because it was still not free flowing, pulled the P-trap over a bucket. Found about a tablespoon of grit and an earring back. Cleaned the trap, brushed the trap arm, replaced one flattened washer. Cost: one pack of washers.
• Minute 32 to 35. Reassembled hand tight plus a quarter turn, ran water one minute, checked with paper towel. Dry.

Total: 35 minutes, two small packets of parts, both tools reusable forever. That is a small fraction of the trip charge alone on a single fixture service call. The zip tool pays for itself the first time you use it.

Prevention, and the truth about grease

Prevention is cheap and boring, which is why nobody does it until the second clog.

Put a strainer on every drain. A mesh basket in a kitchen sink and a silicone hair catcher in each shower cost pocket change and stop the overwhelming majority of clogs before they start. This is the single highest return item in the whole article.

Never put these down a drain:

• Grease, oil, or bacon fat, in any amount, even chased with hot water
• Coffee grounds (they clump and settle exactly like wet sand)
• Rice, pasta, oatmeal, and flour, which keep swelling
• Eggshells, fibrous vegetable peels, celery and artichoke strings
• Paint, joint compound, grout slurry, or plaster water
• "Flushable" wipes, cotton swabs, floss, cotton pads, or paper towels
• Cat litter, even the flushable kind
• Any medication

The grease truth. Hot water and dish soap do not solve grease, they relocate it. Grease that's liquid in your sink cools within a few feet of pipe and coats the walls, and every subsequent bit of food debris sticks to that coating. Over months the pipe narrows until it closes. This is the single most common cause of kitchen sink clogs and it's completely preventable. Pour cooking grease into an old can or jar, let it solidify, and put it in the trash.

Habits that actually help:

• Run hot water for 15 seconds after washing greasy dishes, and again after the disposal runs.
• Cold water while the disposal is running, not hot. Cold keeps fats solid so they get ground and carried away rather than smeared on the pipe.
• Clean tub and shower hair catchers weekly, not monthly.
• Pour an enzyme treatment down the kitchen drain monthly, at night, when no one will run water for hours.
• Fill and release a full basin of hot water in every sink once a month. The volume and velocity scour better than a trickle ever does.
• Pour a gallon of water down any drain you rarely use, such as a guest bath or basement floor drain, every couple of months. A dry trap lets sewer gas into the house.

Frequently asked questions

Does baking soda and vinegar actually unclog a drain?

Partly. The fizzing is a neutralization reaction that produces carbon dioxide and salty water, and it does help loosen soap film and light grease on a slow drain. It will not move a solid blockage. Pour a half cup of baking soda, then a cup of vinegar, cover the drain for 15 minutes, then flush with very hot water. Treat it as maintenance, not as a rescue.

Can I pour boiling water down my drain?

Into a stainless or cast iron sink with metal drain lines, yes. Into PVC or ABS plastic, no. Boiling water at 212F is close enough to the softening point of PVC to deform joints, particularly if it sits in a trap. Use hot tap water, around 120F to 140F, on plastic. Never pour boiling water into a toilet, since thermal shock can crack the porcelain.

How do I know if the clog is in the drain or the main line?

The count tells you. One fixture misbehaving means the clog is local, usually within a few feet. Two or more fixtures, or a fixture that reacts when you use a different one, means the shared line. Gurgling and the lowest drain in the house backing up first are both main line signals. Local clogs are a DIY job, main line clogs are not.

Will a drain snake damage my pipes?

A hand snake used gently will not damage sound drain pipe. Problems come from force. Cranking hard against a solid obstruction can kink the cable or scratch the interior, and in old, corroded galvanized or cast iron it can hole a thin section. Never use a plain snake in a toilet, since it scratches the glaze permanently. Feed slowly, crank rather than shove, and stop if the cable stops advancing.

What is a P-trap for, and can I leave it off?

The bend holds a water plug that stops sewer gas from coming into the room, so no, it can't be left off, even briefly overnight. If a trap has to stay disconnected while you're working, stuff a rag into the open pipe going to the wall and leave a note on the fixture.

Why does my drain smell even though it's not clogged?

Usually biofilm inside the drain and around the stopper, which is a slimy bacterial layer feeding on soap and hair. Scrub the visible drain walls with a bottle brush and hot soapy water, then use an enzyme treatment weekly for a month. If the smell is sewer gas rather than sour, the likely cause is a dry trap in a rarely used fixture, or a venting problem, which is worth a plumber's look.

Are drain cleaners safe for septic systems?

Caustic and acid cleaners are not. They kill the bacteria your septic tank depends on to break down solids, and a disrupted tank takes weeks to recover. Stick to mechanical clearing and enzyme products on a septic system.

How much does a plumber charge to unclog a drain?

A single fixture clear is the cheapest call a plumber makes, and snaking a main line through an accessible cleanout typically runs about double it. No accessible cleanout, emergency hours and weekend rates all push it higher. Most shops quote a flat drain clearing fee plus a trip charge rather than an hourly rate, so ask for both numbers, and ask what happens to the price if the cable does not clear the line. Your local quote is the only real number.

The short version

Mechanical beats chemical every time. A zip tool, a flange plunger, and a willingness to put a bucket under the P-trap will handle almost everything a house throws at you, for less than the trip charge on one service call. Escalate one step at a time, stop the moment more than one fixture is involved, and put strainers in every drain so you don't have to read this page again.

If the fixture itself is on its way out rather than just blocked, shower installation costs and the bathroom remodel cost guide will tell you what replacement really runs.