What it usually means, the likely causes in order, what to safely try first, what a pro charges in Canada, and when to stop and call one.
This guide covers the common cases. Describe your exact problem and get a personalized diagnosis — free to start, with a DIY vs. call-a-pro verdict and a real cost estimate.
A drain that's slow, or that gurgles as it empties, is telling you the pipe is partly narrowed — usually a mat of hair and soap in a bathroom drain, grease and food residue in a kitchen line, or lint and detergent buildup near a laundry drain. The water still gets through, which is exactly why people ignore it, but a partial clog almost never clears itself: it keeps collecting material until the drain stops completely, usually at the least convenient moment. The fixes below start with the free mechanical ones, which also happen to be the ones that work.
A single slow drain is not an emergency — it's a maintenance task for this week. It becomes a priority if the water is backing up rather than just draining slowly, if several drains in the house are slow at once (that suggests the main line, a bigger problem), or if you smell sewage, which can mean gases are being pushed past a failing trap or a blockage is building pressure in the line.
The classic cause for tubs and bathroom sinks: hair wraps around the stopper mechanism and the trap bend, then soap and toothpaste cement it into a mat. It builds gradually, which is why the drain seemed fine last month and isn't now.
Cooking grease goes down liquid and solidifies on the cooler pipe walls further along, narrowing the pipe layer by layer. Coffee grounds and starchy food residue stick to it. The drain often runs fine with cold water and slows with greasy loads.
If clearing the trap doesn't restore flow, the narrowing is further along the branch line that carries this fixture to the main stack. This is snake territory — reachable, but past the point a zip tool can reach.
Drains need air from a vent pipe to flow smoothly. A partly blocked vent makes drains gurgle, glug, and drain slowly as air struggles to move. Gurgling plus slowness at several fixtures that share a vent points here rather than at one trap.
Over years, a drain run can settle so a section holds water instead of sloping to the stack. Solids settle in the low spot and re-clog it regularly — the signature is a drain that clears with snaking, then slows again within weeks.
| Job size | Typical estimate (CAD) |
|---|---|
| Simple fix — the straightforward version of this repair | $120–$250 |
| Major job — complex, hidden, or replacement-level work | $400–$1,200 |
Estimates only, calibrated to Greater Toronto Area trade rates and adjusted by region on this site — not a quote. Your exact price depends on the cause, parts, and access. A personalized diagnosis narrows this range using your specific symptom.
DIY handles most single-fixture slow drains: stopper cleaning, zip tools, plunging, and trap removal are all within reach with a bucket and basic tools. Call a pro when the clog is past the trap and a hand snake doesn't reach it, when multiple drains slow down together, when sewage odour shows up, or when the same drain re-clogs within a few weeks of a thorough clearing — repeat clogs have a cause (a belly, roots, or a damaged pipe) that a camera inspection finds faster than repeated snaking.
Gurgling is the sound of air being pulled or pushed through water in the trap — the drain is struggling to get air as water moves, usually because the pipe is partly narrowed by a clog or the vent path is restricted. A gurgle that appears along with new slowness almost always means a developing clog, so treat it as an early warning rather than a quirk.
They can dissolve some organic material in the trap area, but they do little against a mature clog further down the line, and they add risk — heat and caustic residue in older or damaged pipes, and a hazard for the next person who opens the trap. Mechanical clearing (zip tool or snake) removes the actual obstruction and is why pros reach for it first.
A simple mesh drain catcher over the opening catches most hair before it reaches the trap, and it's the single most effective prevention. Running hot water after use helps soap residue move along, and cleaning the stopper mechanism every few months stops the mat from cementing in place.
The two sides of a double sink usually share the trap and line after a short separate run. If one side drains well, the shared line is likely clear and the problem is in the slow side's own short run or stopper area; if both are slow, look at the shared trap or further down the line.
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