Kitchen Sink Clogged? How to Clear It (Even on Both Sides)

A kitchen sink clogged with greasy, standing water can often be cleared with a plunger, a bucket, and some patience. This guide from Repipe Solutions, a licensed Houston plumbing company, covers how to fix a clogged kitchen sink in the right order, what it means when both sides back up, and when the clog is past what a homeowner can reach.

Before You Start: Two Safety Rules

• If you already poured in a chemical drain opener, do not plunge or snake. The label on Drano Liquid says never to use a plunger during or after use, because the product may still be in the drain if it did not clear. Family Handyman warns the chemicals can cause serious burns if they splash on your skin.
• Never put your hand in a garbage disposal. The InSinkErator owner’s manual says to turn the power off before clearing a jam or pressing the reset button, and to use long-handled tongs or pliers to pull anything out. If the disposal plugs into an outlet under the sink, unplug it. If it is hardwired, switch it off at the breaker.

Clogged Kitchen Sink With a Garbage Disposal: Check the Disposal First

If the disposal side is the side holding water, the disposal itself may be the problem. If it hums or will not run at all, follow our guides to a garbage disposal humming and a garbage disposal not working.

When the disposal spins fine and the sink still holds water, the blockage is further down, in the trap or the drain line past it, so the plunger is the next step. Skip the caustic drain cleaner, too. With a clogged kitchen sink with garbage disposal, those chemicals end up sitting in the disposer, and InSinkErator says they should never go into one.

Plunger for a Kitchen Sink Clog: How to Plunge It Right

Use a cup plunger, the kind with a flat rubber bell, and keep it for the kitchen. Family Handyman suggests keeping at least two plungers, one for toilets and one for sinks and tubs, for hygiene. Then:

1. Clamp the dishwasher hose. If a dishwasher drains into the sink, Family Handyman says to tighten a clamp over the flexible part of the drain hose before plunging, so dirty water does not get pushed back into the dishwasher.
2. Seal the other drain. On a double sink, hold a wet rag tightly over the other drain or set the basket strainer in it. Otherwise the pressure escapes out the second opening.
3. Get water in the basin. You want 3 to 4 inches of water so the plunger seals and pushes water, not air.
4. Plunge hard for about 20 seconds, then pop the plunger off on the last upstroke. Family Handyman says to keep going for several minutes if the water does not swirl away.
5. Switch sides if needed. If one side still will not drain, seal the side you just plunged and work the other one.

If several rounds do nothing, stop plunging and move under the sink.

How to Fix a Clogged Kitchen Sink at the P-Trap

Family Handyman notes that clogs in the P-trap and trap arm most often come from grease or coffee grounds. The P-trap is the U-shaped bend under the sink, and it is held on with slip nuts.

1. Sponge as much water out of the sink as you can, then put a bucket directly under the trap.
2. Loosen the slip nuts by hand or with slip-joint pliers. Go gently; old metal and thin plastic can crack.
3. Pull the trap, dump it into the bucket, and clear it out. Check the trap arm (the short pipe into the wall) too.
4. Reinstall the trap. Family Handyman’s guidance is hand tight plus about a quarter turn with pliers.
5. Run warm water and check every joint for drips.

Snake the Drain Past the Trap

If the trap was clear, the clog is farther along. A hand drain snake (also called a sink auger) is the next tool. Bob Vila notes they are sold at home centers for less than $25, and Family Handyman suggests a 3/8-inch snake about 20 feet long for general use.

• Feed the snake into the pipe stub coming out of the wall with the trap removed, not down through the sink or the disposal.
• Crank clockwise as you push. The first resistance you feel is often the cable turning a corner, so keep feeding.
• When you hit the clog, keep cranking until the tension drops. Pull it back, wipe it, and repeat until it runs freely, then reinstall the trap and flush with warm water.

Skip boiling water as a shortcut. Roto-Rooter says boiling water may damage PVC or older pipes.

Kitchen Sink Clogged on Both Sides: What It Means

Most double kitchen sinks share one trap. The two basins feed a fitting called a continuous waste tee, and the tee drains into a single P-trap. The 2021 International Residential Code adopted in Texas (Section P3201.6) allows one trap to serve two or three adjacent kitchen sinks set up this way. So when the kitchen sink is clogged on both sides, the blockage is not in either basin. It is at the tee, in the trap, or farther down the line.

Kitchen Sink Clogged and You Tried Everything?

If you have plunged, cleaned the trap, and run a hand snake, and the kitchen sink is still clogged, the blockage is usually past the trap arm in the branch line that carries the kitchen’s water to the main drain. That is a drain cleaning job, not a sink problem. A hand snake can poke through years of grease without clearing the pipe walls.

Before you call:

• Are other drains affected? If tubs, toilets, or floor drains are also slow or gurgling, the problem is likely the main sewer line, not the kitchen. Our post on drain line vs sewer line explains the difference.
• Check the city cleanout (City of Houston homes). Houston Public Works says that if your home is backing up, you can check the cleanout located at the street, usually a white plastic pipe with a cap. If sewer water is standing there, call 311. If it is not, the blockage is on your private line and the city tells you to contact a plumber.
• Do not keep pouring products down it. See why chemical drain cleaners are bad for your pipes.

Why Your Kitchen Sink Keeps Clogging

Grease is the number one reason in Houston. Houston Public Works says 70% of sewer overflows in the city are caused by clogs from fats, oils, and grease poured down drains and wipes flushed down toilets. It also reports that crews respond to twice as many grease-related overflows each year when temperatures drop, because holiday cooking makes more grease and colder weather makes it harden faster in the pipes.

The city’s “Protect Our Pipes” campaign puts it simply: put grease in its place, the trash. Its partner toolkit lists three steps:

1. Pour fats, oils, and grease into a safe container.
2. Cool it in the fridge.
3. Toss it in the trash.

The city also recommends wiping greasy pans with a paper towel before washing and using a sink strainer.

Disposal habits. The InSinkErator manual says to run cold water before turning the disposer on and for several seconds after grinding, to flush the line. It warns against pouring grease or fat down any drain and against grinding large amounts of eggshells or fibrous foods like corn husks and artichokes. For a fuller list, see our guide to foods not to put in a garbage disposal.

The drain itself. The code (IRC P3201.1) requires traps with smooth, uniform interior waterways, and ribbed accordion-style drain hoses collect grease in every fold. A trap arm without enough fall, or a deep new sink whose outlet sits near or below the wall pipe, also leaves debris sitting in the line. Those are fixed by reconfiguring the drain, which we handle as part of sink installation in Houston.

If the clog is gone but the sink still smells, see why does my kitchen sink smell.

When to Call a Plumber for a Clogged Kitchen Sink

• You poured in a chemical drain opener and the sink did not clear.
• Plunging, a clean trap, and a hand snake have all failed.
• Both sides back up again within days or weeks of clearing.
• Other drains in the house are slow, gurgling, or backing up too.

When we clear a kitchen line, we match the method to the cause: a drain snake for a clog in the kitchen branch line, and a sewer camera inspection to find the cause when the line keeps clogging or the main may be involved. Clearing a standard kitchen sink line usually falls in the lower part of our drain cleaning range, roughly $150 to $275, and the price is quoted in writing up front. See our drain cleaning service for full pricing.

Frequently Asked Questions

Why does water come up in the other side of my sink when I run the disposal?

Both basins share the same trap. When the line is blocked at the tee, the trap, or beyond, water pushed out by the disposal has nowhere to go but up the other drain. Seal that drain and plunge, then clean the trap if it comes back.

Can I use a toilet plunger on a kitchen sink?

It is better not to. Roto-Rooter recommends a separate kitchen plunger so bathroom germs stay out of the kitchen, and a flat cup plunger is the type made for flat sink drains.

Why does dirty sink water back up into my dishwasher?

The dishwasher drains into the disposal or the sink tailpiece. The code (IRC P2717.2) requires the discharge hose to rise to the underside of the counter before it connects. If the hose sags with no high loop, or the sink is clogged, sink water can run back into the dishwasher. Clamp the hose while you plunge.

Is it safe to pour boiling water into a clogged kitchen sink?

Not into a sink full of standing water, and not into plastic drain pipes. Roto-Rooter cautions that boiling water may damage PVC or older pipes.

Should I call the city if my kitchen sink is backing up?

Only if the city’s side is blocked. In the City of Houston, check the cleanout at the street. Standing sewer water there means a 311 call. A dry cleanout means the clog is on your property and needs a plumber.

Kitchen Sink Still Clogged? Get It Cleared in Houston

Repipe Solutions clears clogged kitchen sinks and branch lines throughout the Houston area. Same-day service is available, and you approve a written price first. See our drain cleaning service in Houston or contact Repipe Solutions to schedule a visit.

Featured photo: “Dirty dishes in a kitchen sink” by Alan Cleaver via Openverse, licensed under CC BY 2.0, converted to WebP.