How to Unclog a Kitchen Sink

Run water on both sides of the sink and watch what happens. If the garbage disposal side drains fine but the other side has standing water, the blockage is probably in the riser pipe directly below the basket strainer. Look down through the strainer - you may spot a straw, a wad of food debris, or a buildup of grease that's narrowed the opening. Knowing which side is clogged tells you exactly where to start.

Get a flat-cup sink plunger - the kind made for flat surfaces, not a toilet plunger. Plug the garbage disposal drain with a stopper or a rag to seal it shut. Set the plunger over the basket strainer so it seats against the sink bottom and covers the drain opening completely. Push down firmly and repeatedly. What you're doing is forcing water pressure against whatever is blocking the pipe. It may take several hard pushes. If the blockage breaks loose, you'll feel the resistance give and the water will drain.

If the clog is on the garbage disposal side, move the plug to the basket strainer side to seal it off. Then insert the handle end of the plunger into the disposal opening and manually spin the grinding plate to break up whatever jammed it. If the disposal is completely unresponsive, reach underneath and press the reset button on the bottom of the unit - it pops out when the motor overloads. Press it back in and try again. Avoid putting your hand into the grinding chamber.

When both sides are backed up or the plunger isn't moving anything, the clog is likely sitting in the P-trap - the curved pipe directly under the sink. Place a bucket underneath it before touching anything. The P-trap holds a full cup or more of standing water and it will all come out when the connection releases. Unscrew the slip joint nuts by hand, working slowly. If they won't budge by hand, use channel-lock pliers - but go easy, these are usually plastic.

With the P-trap removed, look inside it. Grease, food scraps, and hair collect in the curved section over time and can completely block flow. Clean it out over the bucket, then run water through it to clear it fully. Also check the horizontal trap arm - the pipe that runs from the sink into the wall. If water pours back out of the wall when you pull the arm free, the clog is further in and you'll need a drain snake. Check the rubber washers inside each fitting before putting everything back together.

Thread the slip joint nuts back on by hand and snug them up just until they stop - hand-tight only. Over-tightening plastic nuts cracks them, and a cracked nut is a slow leak waiting to happen. Line up the pipes carefully before tightening so nothing is under lateral stress. Work from the trap arm at the wall toward the sink, threading each connection before tightening any of them.

Turn on the hot water and watch the sink. If it starts filling up and not draining, shut the water off - the clog is still in the trap arm or further back in the wall. If it drains freely, let the hot water run for a minute, then reach under and check every slip joint nut with your fingers. Lay a few paper towels flat across the cabinet floor, run a full sink of dishes, then check the towels the next morning. Any drip at all will show on the paper before it ever damages the cabinet wood.

If you've cleared the P-trap and the sink still won't drain, the clog is deeper in the wall - past where hand tools can reach. Feed a drain snake into the trap adapter opening where the arm goes into the wall. Crank it until you feel resistance, then work back and forth until it breaks through. For a clog that won't move, a power drain machine from a rental store is the right tool. If you're not comfortable working in the wall drain, calling a plumber is the practical choice.