How to snake a sink drain from the trap arm, not the plughole

01 /Why snake from the trap arm instead of the plughole?

Snaking from the trap arm works better because it removes three obstacles the cable would otherwise have to pass: the pop-up stopper and its pivot rod, the narrow tailpiece below the basin, and the tight U-bend of the P-trap. Each of those is a place where a thin cable buckles, catches or simply coils up. With the trap off, the cable goes straight into the horizontal pipe that disappears into the wall, which is where the clog usually is if the trap itself was clean.

Taking the trap off is also diagnostic. A bathroom sink trap is 1-1/4 inch (32 mm) and a kitchen trap 1-1/2 inch (38 mm), and both are small enough to fill with hair, toothpaste, soap film, coffee grounds or a dropped cap. Many slow sinks are fixed the moment the trap is emptied into a bucket, with no cable at all.

02 /What do you need before you start?

You need a bucket, a way to loosen the trap, a 1/4-inch hand or drill-powered drum auger with 15 to 25 feet (roughly 4.5 to 7.5 m) of cable, and protection for your hands and eyes. Sink water that has been standing is dirty rather than dangerous, but it can hold residue from cleaning products, so treat it as contaminated.

• Bucket and towels: the trap holds a cup or two of water even when the sink is empty, and more if the basin is full.
• Slip-joint pliers or a large adjustable wrench: plastic slip nuts usually turn by hand; chrome ones may need pliers wrapped in a cloth.
• Hand drum auger, 1/4-inch cable: hollow-core cable is the most flexible for the tee inside the wall.
• Rubber or nitrile gloves and safety glasses: the cable flicks water when it comes out.
• Flashlight and an old toothbrush: for looking into the trap arm and cleaning the trap threads.
• Spare slip-joint washers: old washers often flatten or crack when disturbed.

03 /How do you snake a bathroom sink step by step?

1. Pull and clean the stopper

   Under the sink, find the pivot rod entering the back of the tailpiece. Unscrew its retaining nut, slide the rod out, and lift the stopper out of the basin. Clean off the hair and test the sink. This alone clears a large share of bathroom sinks.

2. Empty the basin

   Bail or sponge standing water into the bucket so it does not dump on you when the trap comes off.

3. Remove the P-trap

   Set the bucket underneath, loosen both slip nuts, and lower the trap. Pour it out and look at what is in it.

4. Look into the trap arm

   Shine a light into the pipe that goes into the wall. If you can see a plug of hair or sludge within a finger's reach, pull it out with a gloved finger or the auger head.

5. Feed cable without rotation

   Pull out about 30 cm of cable, push the head into the trap arm, and keep feeding by hand until it stops. The first stop is usually the tee inside the wall, often within an arm's length.

6. Rotate through the tee

   Lock the thumbscrew so no more than a hand's width of cable is exposed, crank clockwise and push gently. The head should drop down the tee. If it suddenly runs freely upward, see the next section.

7. Work the clog in short bites

   When you meet soft resistance, crank and advance a few centimetres, pull back slightly, and advance again. Unlock, pull out more cable, lock, repeat.

8. Retrieve while cranking clockwise

   Keep turning in the same direction as you pull the cable back, so material stays wrapped on the head. Wipe the cable into the bucket as it comes out.

9. Reassemble and test with volume

   Refit the trap with the washers bevel side toward the joint, tighten plastic nuts by hand plus a quarter turn, refit the stopper, then fill the basin and release it. Run a dry paper towel around each joint to check for drips.

04 /Why does the cable go up the vent instead of down the drain?

The cable goes up the vent because the trap arm meets a sanitary tee inside the wall, and that tee has an open path straight up to the vent as well as a curved path down to the drain. A stiff cable pushed hard tends to follow the outside of the curve and climb into the vent pipe, where there is nothing to clear. You feel it slide freely for a metre or more, which is easy to mistake for breaking through the clog.

The quickest check is the cable itself. Cable that went up the vent comes back dry, clean or dusty; cable that went down the drain comes back wet and dirty. If it came back clean, pull it back to the tee, crank slowly as you push so the head can fall into the downward sweep, and let gravity help rather than pushing hard. A bulb head is heavier at the tip and tends to drop down the tee more readily than a straight coil. Once you find the right path, mark the cable with tape at the trap arm so you know the distance next time.

If the cable will not turn down at all, or stops dead at the tee every time, read why a drain snake is not working, which covers bends, stuck heads and cable that coils instead of advancing.

05 /How is snaking a kitchen sink different?

A kitchen sink is different because its clog is usually grease and food waste further along the branch, not hair near the trap. Fats cool and cling to the pipe wall wherever the drain runs horizontally, so the blockage often sits in the run behind the cabinet or under the floor on its way to the stack, a few metres past the trap.

• Double basins: most have a single trap fed by a continuous waste tee. Plug the second basin with its stopper or a wet rag before plunging, and remove the one trap that serves both before snaking.
• Dishwasher: the dishwasher hose usually drains into the disposal or a tailpiece branch. Do not run cable into the hose. A kitchen clog often shows up first as water left in the dishwasher.
• Reach: a 25-ft hand drum reaches most kitchen branches from the trap arm. If it runs out before the clog, a 5/16 or 3/8-inch drum machine from a basement cleanout on the kitchen line (some houses have one) is the better route.
• Grease: the auger bores a hole through the plug; most of the grease stays on the wall. Flush with several minutes of hot tap water afterwards, and if the sink clogs again within weeks, the line needs cleaning of the full wall. The sister site SewerJetting.ca covers when jetting suits a kitchen line.

Island sinks add a complication: many are vented with a loop under the counter or an air admittance valve instead of a vent through the wall. Follow the drain side of the fitting, not the vent side, and if the layout under the cabinet is unfamiliar, stop and photograph it before taking anything apart.

06 /Can you snake a sink with a garbage disposal?

Yes, but never through the disposal itself. The grinding chamber has an impeller plate and a narrow outlet, and a cable fed through the sink opening will either catch in it or never reach the drain. Snake from the trap below the disposal instead, the same way as any other sink.

1. Cut the power

   Unplug the disposal under the sink, or switch off its breaker if it is hard-wired. Do not rely on the wall switch alone.

2. Rule out a jam

   If the disposal hums without turning, it is jammed, not the drain. Many units have a hex socket in the centre of the underside that lets you turn the motor by hand with the key supplied. Never put a hand into the chamber.

3. Remove the trap below the disposal outlet

   The disposal discharges sideways through a short tube into the trap. Loosen the trap nuts and empty it into the bucket.

4. Snake the trap arm

   Feed 1/4-inch cable into the trap arm as described above, rotating through the tee.

5. Reassemble and run cold water

   Refit the trap, restore power and run the disposal with a strong flow of cold water for half a minute to check flow and leaks.

07 /When should you stop snaking a sink?

• Water rises in another fixture while you work or test, such as the tub beside the bathroom sink. The clog is in a shared branch; run the Clog Locator before going further.
• The cable runs out without meeting the clog and the sink is still slow. Step up to a drum machine or enter from a cleanout closer to the clog; the Auger Cable Sizer gives the cable and length for the line you are in.
• Metal pipe crumbles or leaks where the trap arm meets the wall. Older galvanized trap arms corrode from the inside; disturbing them can start a leak inside the wall.
• The cable kinks or twists instead of advancing. Stop cranking, back off and read the auger cable size chart; the cable may be too light or you may be pushing too hard.
• The sink clogs again within weeks. Grease or a partial obstruction further down is catching new debris; see why the clog came back.

If a tub or shower in the same bathroom is also slow, the technique for those is in how to snake a bathtub or shower drain. If you would rather have a drain professional handle it, you can request quotes and mention whether one fixture or several are affected.

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