What is actually blocking it
Where the blockage is tells you what it is.
One fixture slow, everything else fine. The blockage is local - in the trap or the branch line. Hair and soap in a bath or shower, food and grease in a kitchen sink.
Several fixtures slow, all on one side of the house. A branch line serving that group.
Everything slow, and the lowest drain in the house gurgles or backs up first. The main line. This is the one to take seriously - if a toilet on the ground floor backs up when you run the washing machine, stop using water and call someone.
What a plumber will do
- Locate. Which fixtures are affected narrows it before anyone opens anything.
- Access. Through a cleanout if the property has one, otherwise by pulling a toilet or going through the roof vent.
- Clear. Cable machine for most blockages; jetting for grease, scale, or anything recurring.
- Verify. Run water and watch it drain properly, not just briefly.
A camera inspection is worth paying for when the same line blocks repeatedly, when the house is old enough to have cast iron, or when you are buying the property.
What prevents the next one
- Strainers on every shower and bath
- Grease into the bin, never the sink - it congeals as it cools
- “Flushable” wipes are not flushable; they are the single most common cause of main-line blockages
- If you have mature trees and clay drains, budget for a camera check every few years
Common questions
Can I use a chemical drain cleaner first?
Once, on a slow drain, maybe. Repeatedly, no. Caustic cleaners sit against the pipe wall when they fail to clear the blockage and will corrode older metal traps and joints. They also make the job hazardous for whoever opens the line afterwards - tell your plumber if you have used one.
What is the difference between snaking and hydro jetting?
A snake (auger) bores a hole through the blockage so water flows again. Jetting scours the full diameter of the pipe with high-pressure water, removing the grease and scale the snake left behind. Snaking is cheaper and often enough; jetting lasts longer on recurring blockages.
My drain keeps clogging in the same place. Why?
Recurring blockages in one spot usually mean the pipe itself has a problem - a belly where water pools, root intrusion at a joint, or scale narrowing the bore. A camera inspection tells you which, and stops you paying to clear the same blockage four times a year.