How to Unclog a Kitchen Sink Drain (and When to Call a Pro)

A kitchen sink that drains slowly — or not at all — is one of the most common calls we get in Calgary. The good news: most kitchen clogs sit in the first few feet of pipe and you can clear them yourself in under half an hour. Here's how, in the order a pro would actually try them.

Before you start, skip the chemical drain cleaner. It rarely clears a full grease clog, it can sit in the pipe and damage the older fittings found in many Calgary homes, and it makes the job hazardous for anyone who opens the trap afterward.

Start with the easy wins

1. Hot water. Kitchen clogs are usually grease, soap, and food softened into a plug. Heat a kettle and pour it down in two or three stages, a few seconds apart, to let the heat work. If the pipes under your sink are white or black plastic, let the kettle cool for a minute first — near-boiling water is kinder to plastic joints. If the water starts draining faster, you're on the right track — repeat once more.

2. Clear the basket and standing water. Pull out the sink strainer and scoop out any standing water so you're working on the clog, not a full basin. Check the strainer itself isn't the whole problem.

3. Plunge it. A flat-bottomed sink plunger works well here. If you have a double sink, stuff a wet rag tightly into the other drain first — otherwise you just push air back and forth. Cover the drain, add enough water to seal the cup, and give it 6–8 firm pumps.

Open the P-trap

If plunging doesn't do it, the clog is likely sitting in the P-trap — the U-shaped pipe under the sink that catches everything.

• Put a bucket and some towels underneath. It will hold dirty water.
• Unscrew the two slip nuts by hand (or with channel-lock pliers) and lower the trap.
• Clear out the gunk, rinse the trap, and check the arm that goes into the wall.
• Reassemble, then run warm water and watch the joints for drips.

In a kitchen, the clog is very often right here.

Try a household drain snake

If the trap is clean and the sink still won't drain, the plug is in the pipe inside the wall. A small hand-crank drain snake from the hardware store can reach it:

1. With the trap still off, feed the cable into the arm that goes into the wall.
2. When you feel resistance, tighten the lock and turn the handle clockwise while pushing gently forward. You're trying to bore through the plug or hook it, not ram it.
3. Pull the cable back slowly and wipe it off as it comes out — it will be greasy.
4. Reattach the trap and flush the line with a kettle of hot water, followed by a few minutes of hot tap water.

Don't force the cable if it keeps catching at the same spot. A tight bend or an old fitting can be damaged by too much pressure, and that's the point where a pro with the right equipment is the safer choice.

Check the dishwasher and disposal connections

Many kitchen sinks share the drain with a dishwasher, a garburator or both. If the sink backs up when the dishwasher runs, check the drain hose where it joins the sink tailpiece or disposal for a kink or a food plug. With a garburator, run it with cold water to clear any ground-up food sitting in the unit, and make sure the knockout plug was removed if the dishwasher was recently installed. Calgary's hard water also leaves scale inside the disposal and tailpiece over time, which gives grease more to cling to.

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Frequently Asked Questions

Is it safe to use chemical drain cleaner on a kitchen sink?

It is best to skip it. Chemical cleaners rarely clear a full grease clog, can damage older fittings, and make it hazardous for anyone who opens the trap afterwards. Boiling water, a plunger, and cleaning the P-trap work better for most kitchen clogs.

Can I pour boiling water down a clogged kitchen sink?

Very hot water helps soften grease and soap clogs. Pour it in two or three stages a few seconds apart, and let the kettle cool slightly first if the pipes under the sink are plastic. If standing water is sitting in the sink, scoop it out first so the heat reaches the clog.

How do I plunge a double kitchen sink?

Stuff a wet rag tightly into the other drain first so you are not just pushing air back and forth. Use a flat-bottomed sink plunger, add enough water to seal the cup, and give it six to eight firm pumps.

Why does my kitchen sink keep clogging?

Grease is the most common repeat cause in Calgary kitchens. If the clog returns within a day or two, or more than one fixture backs up at once, the blockage is likely further down the line. In older homes, scale inside aging cast-iron pipes can also be the cause.

When it's time to call a pro in Calgary

A few signs mean the blockage is further down the line than a DIY fix can reach — and worth a professional with a proper drain auger:

• The clog comes back within a day or two of clearing it.
• More than one fixture backs up at once (sink and dishwasher, or a gurgle in another drain). That points to the main line.
• Water backs up out of another drain when you run the sink.
• You can smell sewer gas or see dark water rising.

Those are signals the issue is past the trap, and snaking it blind can pack the clog tighter or damage the pipe. In older Calgary homes — the established inner-city streets in particular — aging cast-iron lines scale up inside, so a clog that keeps returning often points to the pipe itself rather than what you put down it.

Quick tip to prevent the next one: wipe grease into the garbage before it goes down the sink, and run hot water for 10 seconds after washing oily pans. Grease is the most common repeat offender in Calgary kitchens.

If you'd rather not pull the trap apart — or the clog has already come back — YOFF drain cleaning starts from $100 across Calgary and nearby communities. Our technician clears the kitchen line with a proper auger, tests the flow, and you only pay if we fix it. Book a drain cleaning or call us and we'll take a look.