Drain care
Why Does My Kitchen Sink Keep Clogging, and How Do I Stop It?
A kitchen sink that keeps clogging is almost always grease and food residue building up inside the drain line, and a few changes to what goes down the drain can stop it from coming back.
A kitchen sink that keeps clogging is almost always caused by grease, oil, and food particles sticking to the inside of the drain pipe a little more every time you wash a pan or rinse a plate. Unlike a bathroom clog, which is usually one obvious blockage, kitchen clogs tend to build up slowly in layers until the pipe is narrow enough that water backs up. The good news is that most of it comes down to a few habits, and the fixes are usually simple.
Why does grease cause so many kitchen sink clogs?
Grease and cooking oil go down the drain as a warm liquid, but pipes are cooler than your stove, so the fat cools and hardens as it travels through the line. That hardened layer coats the inside of the pipe and catches everything that flows past afterward — coffee grounds, rice, flour, vegetable peels — until the opening left for water gets smaller and smaller. This happens gradually, so a sink often seems fine for weeks and then starts draining slowly all at once, which is really the moment the buildup finally caught up with itself. It's also worse in older Toronto homes with narrower or aging drain lines, where there's less room for buildup before it becomes a real blockage.
What should never go down a kitchen sink drain?
Grease and oil from cooking are the biggest offenders, but they're not the only ones. Coffee grounds and eggshells don't dissolve and tend to pack together with grease rather than flush through on their own. Starchy foods like pasta, rice, and potato peels can swell or turn gummy inside the pipe. Even with a garburator running, fibrous vegetable scraps like celery or onion skins can wrap around the blades or catch further down the line instead of breaking apart cleanly. The simplest habit that prevents most of this is wiping greasy pans with a paper towel before washing them and scraping food scraps into the garbage or green bin rather than rinsing them straight down the drain.
Does hot water flush grease away, or make it worse?
It's a common assumption that running hot water while you wash dishes will carry grease safely through the pipes, but it mostly just moves the problem further down the line. The grease stays liquid while the hot water is running, but once it cools inside the pipe — which happens quickly once it's a few feet from the tap — it hardens again, often somewhere less convenient to clear. Hot water isn't harmful to run, but it isn't a real fix either, so it shouldn't be the reason you feel comfortable pouring grease down the sink.
What can I do if my kitchen sink is already draining slowly?
A kettle of hot (not boiling, if you have older pipes) water followed by a mix of baking soda and vinegar can loosen light buildup, and a sink plunger or a drain snake designed for kitchen use can often clear the rest. Avoid chemical drain cleaners in a kitchen sink that's already slow, since they can sit in the pipe and cause damage without actually reaching a grease clog that's coating the walls of the pipe rather than blocking it in one spot. If the slow drain keeps coming back within days of clearing it, that's usually a sign the buildup extends further down the line than a plunger or basic snake can reach.
When is it time to call a plumber for a kitchen sink clog?
Call a plumber if the clog comes back repeatedly despite clearing it yourself, if water backs up into the other side of a double sink, if you notice a slow drain in the kitchen along with gurgling elsewhere in the house, or if a plunger and drain snake haven't made a difference. Professional drain clearing reaches further into the line and clears the pipe fully rather than just pushing the blockage along, and with GetFixHero that typically runs $125–250. If the clog turns out to be tied to the garburator itself rather than the pipe beyond it, that's worth mentioning when you call, since it can change what the fix looks like.
Frequently asked questions
Can I ever pour grease down the sink if I run the garburator first? No — a garburator chops food waste into smaller pieces, but it doesn't change how grease behaves once it's in the pipe, so cooled grease will still coat the line and catch debris the same way whether or not it went through the garburator first.
Is it better to collect grease in a container instead of the sink? Yes, and it's the single most effective habit for preventing kitchen clogs — let grease cool in the pan or a heat-safe container, then scrape it into the garbage rather than washing it down the drain while it's still liquid.
Does a garbage disposal make grease clogs more or less likely? Less likely for food that would otherwise sit in the pipe and trap grease, but a garburator doesn't process grease itself, so the habit of scraping grease into the garbage still matters even in a kitchen that has one.
A little care about what goes down the kitchen drain saves you from a much bigger clog later — request a plumber or message us on Facebook. Free for homeowners, care of GetFixHero.
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