Why Does My Drain Keep Clogging? Common Causes & Fixes

Drains & Sewers

A clogged drain that clears with a plunger and never comes back is a minor annoyance. A drain that clogs again every few weeks is a sign of something more serious happening further down the line, and it's one of the most common issues we get called out for across York Region. Here's what's usually going on, how to tell which drain is blocked, and when it's time to stop reaching for the plunger and book professional drain cleaning.

Which Drain Is It?

A kitchen sink that slows every few months is usually grease and soap in the kitchen line, which often runs long with little slope. A tub or bathroom sink is usually hair and soap scum at the trap or the branch line. When the tub fills as the toilet flushes, or the basement floor drain gurgles as the washer empties, the fixtures are sharing one blockage and it is in the main line. Call before it comes up the floor drain. For a single slow fixture, see clogged sink repair.

Buildup Further Down the Line

Grease, soap scum, hair, and food residue don't always wash all the way through your plumbing, they can collect along pipe walls further down the line, gradually narrowing the passage until water can barely get through. Surface-level fixes like plungers or store-bought drain cleaners only address what's immediately visible, not the buildup that's actually causing the recurring problem. Chemical drain cleaners do not clear roots or fix a sagging line, and they are hard on older metal pipe.

Tree Root Intrusion

This is especially common in older neighbourhoods across Newmarket, Aurora, Thornhill and North York, where mature trees stand over older clay sewer laterals. Roots are drawn to the moisture inside pipes and can work their way into small cracks or joints, gradually restricting, and eventually blocking, the flow entirely. If multiple drains in your home are slow at the same time, root intrusion in your main line is a strong possibility.

A Sagging Section of Pipe

Buried drain lines usually sag because the soil under them settles: fill that was never properly compacted, clay that shrinks in a dry summer, or wet organic ground like the land around the Holland Marsh. A low section, which plumbers call a belly, holds water and catches everything that goes past, so the same spot clogs again no matter how often it is snaked. A camera shows the water sitting in the belly, and a locator marks where to dig if the section needs replacing.

Signs It's Time to Call a Professional

• The same drain clogs repeatedly, even after clearing it
• Multiple fixtures are slow to drain at once
• You notice gurgling sounds from drains or toilets
• There's a persistent bad odour coming from a drain
• Water backs up into a different fixture when you run another

How We Diagnose It Right the First Time

Most repeat clogs start with a cable machine run from the nearest cleanout, sized to the line. When the same line keeps blocking, we follow up with a camera inspection and walk you through the footage: roots at a clay joint, a belly holding water, a cracked section or a coating of grease. Grease and scale usually call for hydro jetting, which scours the pipe wall instead of punching a hole through the blockage.

What changes the cost is how far the blockage is from an accessible cleanout, whether the line needs jetting rather than cabling, and whether the camera finds a broken section that needs a spot repair or digging.

If water comes up the basement floor drain during heavy rain, the city sewer is usually surcharging and a backwater valve is the fix; ask us about municipal subsidy programs.