Clogged Drain: Safe Checks and When to Call a Plumber

Likely causes

Possibilities to verify in person, not a remote diagnosis:

Single fixture

• Hair and soap buildup in a tub or shower drain.
• Grease and food debris in a kitchen line, sometimes with a disposal involved.
• An object flushed or dropped into a toilet.
• Scale and residue narrowing an older branch line.
• A blocked or damaged vent, which shows up as slow draining with gurgling.

Multiple fixtures or the main line

• Root intrusion at joints in an older sewer lateral.
• Sagging, cracked, offset or collapsed pipe.
• Accumulated debris in the main run.
• Non-flushable wipes and similar products lodged in the line.
• A municipal-side or shared-line issue.

Safe checks you can do

• Test every drain in the home and note which are slow, which are stopped, and which are normal.
• Listen for gurgling in one fixture while another drains.
• Remove visible hair from a shower or tub strainer by hand with gloves on.
• Try a plunger on a single fixture only — never after any chemical has been used in that drain.
• Pour hot tap water down a slow kitchen drain. Do not use boiling water on plastic piping.
• Look outside for a cleanout cap and note whether water is standing there. Do not open a pressurized or overflowing cleanout.
• Note any recent history: repeat backups, prior work on the line, or new landscaping and tree growth.
• Take photos of the affected fixtures and any water outside.

What not to do

• Do not pour chemical drain cleaner, and never mix two products together — the reaction can release harmful fumes.
• Do not snake or plunge a drain after chemicals have been used in it. Tell the plumber what went in.
• Do not run a rented power auger into a main line or a toilet without knowing what is there; it can damage the pipe.
• Do not keep flushing a stopped toilet to "push it through."
• Do not enter, mop, or vacuum contaminated water.
• Do not remove a cleanout cap when water is under pressure behind it.
• Do not reach a hand into a disposal, and never operate one while an object may be inside.

When professional help is warranted

Get help when more than one fixture is affected, when a toilet or floor drain backs up, when the same drain clogs repeatedly, when there is sewage odor or contaminated water, when the home has an older sewer lateral or mature trees over the line, or when a single fixture does not clear with a plunger. Repeat main-line clogs are usually a line condition, which is why a camera inspection is common on sewer line service calls. For a single stubborn branch, see drain cleaning, and treat an active backup as emergency plumbing.

Have this ready before you call

• Which fixtures are slow or stopped, and which still drain normally.
• Whether any waste water came up, and where.
• Whether anything was poured, plunged, or snaked already — chemicals especially.
• Photos of the fixture, any backup, and the outside cleanout if you can find one.
• Approximate age of the home and whether it is on a slab.
• Whether the property is on municipal sewer or a septic system.
• History of previous backups or line work.
• Your address and best callback number.

Related help on this site

• Drain cleaning
• Sewer line services
• Emergency plumbing
• Toilet keeps running after you flush