A washing machine that smells sour, musty or faintly metallic is a common complaint in St. Louis homes, especially in older houses where the laundry sits in a basement or utility room. The smell usually comes from something sitting in the machine, the drain, or the water supply, not from the clothes. Sort the possibilities into three groups: the machine itself, the drain, and the water coming in. Work through them in that order, since the first two are cheap and quick to check.
Check the machine first
- Door seal: On a front-load machine, pull back the rubber gasket around the door and look at the folds. Damp folds with gray or dark spotting point to mold, which grows in standing moisture.
- Detergent and softener drawers: Pull them out and rinse them. Old detergent and fabric softener build up into a slimy paste that smells sour.
- Drain pump filter: Many machines have a small filter behind a panel near the bottom front. Lint, hair and coins collect there, and the trapped water can smell bad.
- Drum: Run an empty hot cycle with a washer cleaner made for the purpose, and follow the label. Leave the door open afterward so the drum dries out.
Check the drain and standpipe
The floor drain or standpipe that takes the wash water is the next suspect. If the floor drain trap has dried out, sewer gas can come up through it, and that smell often gets blamed on the washer. Pour a bucket of water into the floor drain to refill the trap, then check again after a day. Also look at the drain hose where it meets the standpipe. Slime and lint can build up there, and a quick scrub with a long brush usually clears it.
Check the water coming in
If the smell is metallic, or the wash leaves faint orange flecks on the drum or on light-colored clothes, iron may be part of the picture. Iron in water can feed slime-forming bacteria in pipes and appliance lines, and that slime can give off an odd smell. Hot water is the first place to look, because the water heater and the hot line often carry more iron residue than the cold side. A rough check is to compare the two sides.
Simple tests you can run at home
- Run a short cycle with cold water only, with no clothes in the drum, and smell the drum and the drain afterward.
- Repeat the same short cycle with hot water only.
- Fill a clear glass from the laundry faucet, let it sit for a while, and watch for cloudiness or orange flakes settling to the bottom.
- Smell the water from the glass and note whether it is metallic, sour or closer to rotten eggs.
If only the hot side smells, or the glass test shows flakes, the water heater or the hot line is the place to focus. If both sides smell the same, the problem is more likely the machine or the drain.
When to call for help
If the smell comes back after you clean the gasket, drawers, filter and drain, call a licensed plumber in the St. Louis area. A plumber can inspect the water heater, the hot line and the laundry standpipe, and can flush or sample the lines if needed. A lab test for iron gives more precise answers than a glass test at home, and it is worth doing if you want to know the actual level in your water before deciding on any fix.
Keep a short note of what you checked, what you changed and what the smell was like after each step. That record makes it much easier for a plumber or testing lab to pick up where you left off. This guide is general information about common causes, not a diagnosis of your plumbing or your water.