How to Unclog a Sink Drain

Occasional clogs in the sink, tub, or shower drains are a fact of life. They are usually caused by localized clogs in the drain trap or branch drain for a single fixture. However, if you have several fixtures that are draining slowly or not draining at all, the problem may be in the main drain or sewer line in your home.

Here's how to unclog a sink using several methods:

• Use a plunger.
• Try a sink auger.
• Remove the drain trap to auger the branch drain.
• Use a mild, non-toxic, and biodegradable drain cleaner.
• Try a baking soda and vinegar solution.

Read on for details and tips for each method.

Try Using Boiling Water to Fix a Clogged Sink

Most clogs in sinks and tubs are due to a combination of hair, grease, soap residue, and tepid water that are trapped in the drain trap right below the drain opening. If you have metal pipes, you can try to loosen the clog with hot water—very hot. Pouring a pot of boiling water directly down the drain into the trap may dissolve the clog, especially if it consists of soap scum or grease. Hot tap water won't do the trick—it has to be boiling water.

Boil a gallon of water in a large pot or tea kettle. Something that will allow you to pour directly into the drain, such as a tea kettle, is best. When it's at a rolling boil, carefully carry it over to the clogged sink. Pour the water slowly into the drain. Be careful not to splash the water, as this can lead to burns. Give it a few minutes to dissolve the clog. If it doesn't work, proceed to the steps below.

How to Unclog a Sink Using a Plunger

Two types of drain plungers are common for home use: the cup plunger and the flange plunger (also called a toilet plunger). For working in sinks, showers, and tubs, use a cup plunger.

Prepare for Plunging

If you are working on a bathroom sink, seal the sink overflow outlet found at the top of the sink bowl, just under the rim. Cover the hole with a piece of duct tape or stuff it with a damp rag.

If you are working on a bathtub, apply duct tape over the overflow opening at the front of the tub.

If the clog is in a kitchen sink, lift out the removable basket strainer. If the clog is in a bathroom sink, remove the drain stopper. Try lifting it out or turning and lifting.

Fill With Water

Fill the sink bowl, tub, or shower pan with several inches of water. This will allow the cup of the plunger to form a tight seal.

Seal the Plunger

Place the cup plunger over the drain opening and make sure it has a good seal against the surface around the drain.

Use Your Plunger

Using quick, sharp plunges, pump up and down several times to attempt to clear the obstruction. You may need to hold your hand over the duct tape or wet rag sealing the overflow opening—the air pressure caused by the plunging motion may cause the tape to loosen.

Run the Water

Let the faucet run for a minute or two after the drain is clear.

Replace the Stopper

Remove the overflow outlet seal and replace the drain stopper or sink basket.

Use a Sink Auger for Stubborn Clogs

If the plunger did not clear the clog, try a sink auger (also called a drum or canister auger or a drain-cleaning snake.)

Remove the Stopper

Remove the drain stopper, as applicable.

Insert the Auger

Extend the auger cable into the drain opening. When you feel it bump up against the clog, pull out about 12 inches more of the cable and tighten the setscrew on the auger canisters.

Turn the Auger Handle

Turn the crank handle of the auger clockwise while applying moderate pressure on the cable. The cable end may get stuck on the clog or bends in the pipe; turning the cable helps break up the clog or get the cable end past the bend.

Extend the Cable as Needed

Extend more cable as required until you feel you've worked through the clog. This should work if the clog is in the trap.

Remove the Auger From the Drain

Pull the cable out of the pipe, pushing it back into the canister as you go. The cable may have a large hair clog stuck to its end when it comes out of the drain. Repeat the process as needed until the clog is cleared.

Run the Water

Flush with hot water from the faucet once the drain starts to flow.

If you have extended the cable all the way through the trap without contacting a clog, then the clog is probably in the branch drain or the vertical drain stack in the wall past the branch drain. To get at these pipes, you'll have to remove the drain trap.

Remove the Drain Trap to Auger the Branch Drain

For clogs beyond the trap, getting to them is a bit more work but is still fairly easy.

Place the Bucket

Place a bucket under the trap to catch the water that will come out once the trap is removed.

Remove the Slip Nuts and Drain Trap

Loosen the slip nuts at each end of the trap with tongue-and-groove pliers or a pipe wrench. Remove the slip-nuts and the trap. Note how the nylon slip washers are oriented on the pipe, to make reassembly easier.

Dump the Water

Dump the water in the trap into the bucket. Water will also drain from the disconnected ends of the pipe.

Insert the Auger

Insert the auger cable into the horizontal section of the drainpipe, tighten the setscrew, and crank the cable, as before. If the end of the cable gets stuck at a pipe bend, cranking the auger and applying pressure will help get it past the bend.

Extend the Cable as Needed

Work the cable farther into the drain until you feel you've worked through the clog, then remove the cable.

Replace the Drain Trap and Flush

Reassemble the drain trap and flush the drain with hot water from the faucet to clear any remaining debris.

What About Chemical Drain Cleaners?

If all else fails and you want to use a drain cleaner, opt for a mild, non-toxic, and biodegradable drain cleaner. You can also try a baking soda and vinegar solution.

Do not use chemical drain cleaners. They may cause damage to the environment or the drain pipes in your plumbing system, and these caustic chemicals can be very dangerous to use.

In addition to their danger, chemical cleaners rarely work on stubborn clogs. And after they fail, you will be left with a sink full of water and toxic chemicals that you must bail out by hand.