The most common cause: a clogged drain or vent line

A sewer smell from your washer usually means water is sitting in the drum or drain hose instead of flowing out completely. This stagnant water grows bacteria and mold, which produce that sewer-like odor. The blockage can be in three places: the drain hose itself, the standpipe (the vertical pipe your hose connects to), or the washing machine's internal drain pump.

Start by checking the drain hose. Unplug the washer, pull it away from the wall, and look at the hose running from the back of the machine to the wall. If you see kinks, bends, or a crushed section, straighten it out. A kinked hose traps water and creates the perfect environment for odor-causing bacteria. If the hose looks fine, the clog is likely deeper in the standpipe or pump.

Key Takeaways

  • Sewer smells come from stagnant water trapped in the drain hose, standpipe, or internal pump, where bacteria and mold grow.
  • Straighten any kinked drain hose and run a cleaning cycle with hot water and vinegar or a commercial washer cleaner to flush out buildup.
  • If the smell persists after cleaning, the standpipe or drain pump may need professional inspection, especially in older homes or those with plumbing issues.
  • Regular maintenance—running a cleaning cycle monthly and leaving the door open between loads—prevents odor from returning.

How to clean the drain system yourself

Before calling a plumber, run a cleaning cycle designed to flush out the drain. Most modern washers have a "Clean Washer" or "Tub Clean" cycle; check your manual for the exact name. If your washer does not have this cycle, run a hot water wash on the longest cycle with no clothes inside.

Add one of these to the drum: two cups of white vinegar, or a commercial washer cleaning product like Affresh or Tide Washing Machine Cleaner. Do not mix vinegar and commercial cleaners. Run the cycle completely, then run a second hot water cycle with nothing in the drum to rinse. This flushes out mold, bacteria, and soap residue that accumulates in the pump and hose.

Repeat this cleaning once a month to prevent odor from building up again. Many people find that monthly cleaning eliminates the smell entirely without needing further repairs.

When the standpipe is the problem

The standpipe is the vertical pipe in your wall that your drain hose connects to. If the standpipe is clogged or too small, water backs up into the hose and sits there between cycles. This is especially common in older homes where the standpipe was installed decades ago and has accumulated lint, hair, and soap buildup.

You can try clearing it yourself if you are comfortable working with plumbing. Disconnect the drain hose from the standpipe and look inside with a flashlight. If you see visible debris, use a plumbing snake or a straightened wire coat hanger to pull it out. Pour hot water down the standpipe to flush it. If nothing comes out or the smell returns within a week, the clog is deeper and a plumber will need to snake the line from the cleanout access point.

Checking the drain pump filter

Many washers have a small drain pump filter that catches lint and debris before water leaves the machine. Over time, this filter clogs and traps water, creating odor. The filter is usually located at the bottom front of the washer behind a small panel or door.

Unplug the washer and locate the filter access panel in your manual. Open it carefully—there may be a small amount of water inside. Place a towel underneath to catch spills. Remove the filter by turning it counterclockwise. Rinse it under hot running water and use an old toothbrush to scrub away lint and buildup. Reinstall it by turning it clockwise until snug, but do not overtighten. Run a hot water cycle to test.

Why leaving the door open matters

Moisture trapped in the drum between loads creates the conditions bacteria need to grow. After each wash, prop the door open for at least two hours so the drum can dry completely. This straightforward habit prevents odor from developing in the first place.

If you have a front-load washer, also wipe the rubber gasket (the seal around the door) with a dry cloth after each load. Water and lint collect in the folds of the gasket and cause smell. Many people do not realize this gasket is removable—check your manual to see if you can pull it out and rinse it under hot water monthly.

When to call a plumber

If you have cleaned the drain, run the washer cleaning cycle twice, and the smell returns within a few days, the problem is likely in the home's plumbing system, not the washer itself. A plumber can snake the standpipe from the main cleanout, check for a blocked vent line, or inspect the P-trap under the sink to which the standpipe connects.

Sewer smell can also indicate a problem with your home's vent stack—the pipe that allows sewer gases to escape through the roof. If the vent is blocked or damaged, gases back up into the drain system and into your washer. This is not something you can fix yourself and requires a plumber's inspection.

Frequently Asked Questions

Can I use bleach to clean the washer drain?

Bleach can damage rubber hoses and seals inside the washer, so avoid it. Vinegar and hot water work just as well and are safer for the machine. If you prefer a commercial cleaner, use one designed for washing machines, which are formulated to be safe for all washer parts.

Does the smell mean my washer is broken?

Not necessarily. Odor is usually a sign of buildup or stagnant water, not a mechanical failure. Most washers that smell work fine otherwise. Cleaning the drain and running maintenance cycles often solves the problem without repair.

What if the smell is coming from the hot water line, not the drain?

If the smell only happens when you use hot water, the issue is likely in your home's water heater or hot water pipes, not the washer. Run hot water from a sink faucet and smell it. If it smells like sewer, contact a plumber about your water heater. If the sink water smells fine, the problem is the washer's hot water inlet valve.

How often should I run the cleaning cycle?

Once a month is standard maintenance for most households. If you wash frequently, use a lot of detergent, or live in an area with hard water, run it every two weeks. If you rarely use the washer or always leave the door open, monthly is enough.