There is a difference between a drain that blocked once and a drain that blocks repeatedly, and it is worth taking seriously. A one-off is bad luck. A pattern means something structural, and clearing it again will buy you the same interval it bought you last time.
What actually builds up, by drain
Kitchen sinks clog with grease more than anything else. Fat goes down warm and liquid, then cools on the inside of the pipe and hardens. Each wash adds another layer, the pipe narrows, and eventually food debris that would have passed catches on it. The blockage you eventually get is food; the reason you got it is grease.
Coffee grounds and rice make it worse — grounds are abrasive and settle in low spots, rice swells.
Bathroom sinks clog with hair bound together by soap scum and toothpaste. It forms a mat that catches everything else. The stopper mechanism is usually where it starts.
Showers and tubs are hair too, and it collects further down where the drain turns.
Toilets block on things that should not be there. The main one is wipes — including the ones sold as flushable, which do not break down the way toilet paper does. Municipal wastewater systems across Metro Vancouver spend real money on this.
Laundry drains catch lint and fabric residue.
Why the same one, repeatedly
If clearing a drain buys you three months, and three months later you are back, the useful question is what makes that specific drain different.
Slope. Drains rely on gravity, and there is a right amount of fall. Too little and waste moves too slowly and settles. Too much and water runs away faster than the solids, leaving them behind. Both produce a drain that works but accumulates. This is common where a kitchen or bathroom was moved during a renovation and the new drain was routed to fit the space rather than to fall correctly.
Sags. A drain line that has settled in the middle holds standing water, and standing water is where everything collects. Common under slabs and in long horizontal runs.
Undersized pipe, or a reduction where there should not be one.
Rough interior. Old galvanised drain pipe corrodes internally and gets rough and narrow. Debris catches on the roughness. Once a pipe is like that, cleaning it restores flow briefly and the roughness is still there.
A partial obstruction downstream — a root intrusion, a crushed section, an offset joint — that lets water past but catches solids. This one presents as a drain that works fine on its own and blocks whenever there is real load.
Venting. Drains need air to flow properly. A blocked or missing vent produces slow drainage and gurgling, and it is frequently misdiagnosed as a clog because clearing the line seems to help temporarily.
The signal that it is not local
One slow drain is a local problem. But if more than one fixture is slow, or a toilet bubbles when the washing machine drains, or the shower backs up when the toilet flushes, the problem is not in the fixture's own trap — it is in the shared line downstream, and it is a different job.
That distinction matters, because plunging and chemicals will not touch it, and it tends to become an emergency eventually.
Why chemical drain cleaners are a poor answer
They are marketed for exactly this situation and they are the wrong tool for most of it.
They do not clear a genuine obstruction — they reach the top of it, react with whatever is nearest, and stop. They sit in the pipe afterwards. On old or plastic pipework the heat they generate can cause damage. And the next person to open that drain has to deal with a pipe full of caustic liquid, which changes how the work has to be done.
If you have already used one, say so when you call. That is not a criticism — it genuinely affects how the job is done safely.
What breaks the cycle
Clearing a recurring drain properly means finding out why it recurs, which usually means putting a camera down it. A camera shows slope, sags, roughness, roots, offsets, and the actual condition of the pipe — and it turns "clear it again" into "here is why."
Sometimes the answer is a repair. Sometimes it is that this line needs periodic maintenance and now you know the interval. Either is better than being surprised twice a year.
Living with it better
Grease into the bin, not the sink. Strainers on shower and sink drains — the single most effective thing you can do, and it costs almost nothing. Only toilet paper down the toilet.
And if a drain has started running slower than it used to, deal with it while it is slow rather than after it has stopped. A slow drain can be cleared calmly; a blocked one on a Sunday cannot.
Vancouver, Burnaby, Richmond, Coquitlam, Port Coquitlam, New Westminster. 604-865-7979.
Related: Drain cleaning and unclogging · Drain camera inspection · Hydro jetting
