How to Locate Drain Clogs

Every plumbing fixture in your home carries waste to the sewer or septic tank via a system of drainpipes. Also connected to this system are vents, which expel sewer gases out the roof. Each fixture has a “trap”—a U-shaped pipe (in the case of a toilet, part of the fixture itself)—that contains water to block sewer gases from entering your home.

When a fixture is blocked, check other toilets, sinks, and tubs to see if they’re also draining improperly. If only the one fixture is clogged, the stoppage is usually located in that fixture’s trap or branch drain. If other fixtures are backed up, the blockage is probably beyond where they join a branch line.

Backups at lower points in the system—or throughout the entire system—usually mean that the main stack or sewer line is clogged. To remedy this situation, it’s usually wisest to call in a plumber.