A sour or musty smell coming from a washing machine is frustrating because the machine may look clean, and the clothes can still smell after a full cycle. In St. Louis homes, the source can be the water coming into the machine, the drum and door seal, or the drain line. You do not need to scrub anything before you start. Begin by figuring out where the smell is coming from.
Start with the water you are washing with
Before you clean the machine, check the supply water. Fill a clean, clear glass from the cold tap closest to the washer. If your machine uses hot water, fill a second glass from the hot tap. Smell each glass right away, then wait a few minutes and smell it again. Tap water should have little or no odor, so if either glass smells sour, musty, or like rotten eggs, the supply is part of the problem and deserves its own look.
If both glasses smell fine but the washer still smells sour, the water is probably not the main source. If only the hot glass smells, the water heater or the hot water lines may be the next place to check. A hot-only odor often needs separate testing, because the cold supply can be fine while the heated side is not.
Check the door seal and the drum
Front-load machines are known for trapping moisture in the rubber gasket around the door. Pull the seal gently away from the drum and look for standing water, lint, detergent residue, or dark film. Wipe the gasket and the inside of the drum with a clean cloth, then look at the glass in the door for buildup. If you find slime or a dark film, that residue is a likely source of the smell, even when the water tests fine.
Top-load machines need a different check. Lift the lid and look at the area around the agitator and the rim of the tub. Pull out the detergent and softener dispenser drawer and rinse it. Old product can sit in the drawer, stay damp, and smell sour between cycles.
After cleaning, leave the door or lid open between loads so the inside can dry. A closed, damp drum is one of the most common conditions behind a lingering smell, so drying time matters as much as cleaning.
Look at the drain and the standpipe
A sour odor can also come from the drain side. Check that the drain hose is not kinked, cracked, or sitting in standing water. The hose should connect to the standpipe or drain according to the machine instructions. If the drain trap under the standpipe has dried out, sewer odor can travel back into the laundry area. Pouring a few cups of water into the drain to refill the trap usually fixes that case, and it is a simple check to make before you assume the washer is at fault.
Run a clean-water test cycle
Once the drum and drawer are dry and clean, run an empty hot cycle using a washer cleaning product made for drum cleaning. Follow the label directions for amount and cycle type. When the cycle finishes, open the door and smell the drum right away. Then run a second empty cycle with cold water and smell again.
If the hot cycle smells but the cold does not, focus on the hot supply and the heater. If both cycles smell after cleaning, the buildup is probably inside the machine, and a more thorough cleaning or a service check may be needed. If the cycles are clean but clothes still smell after washing, look at your detergent amount, how long damp clothes sit in the drum, and whether the laundry itself was left wet too long.
When to test the water more formally
If the glass from the cold tap smells sour or musty, a basic home check will not settle the question. A water test from a qualified laboratory can show what is in the supply, and a St. Louis homeowner can ask the lab which tests fit a smell complaint. Keep the glass samples you collected, note which tap they came from, and mention the day and time you smelled them. Those notes help a lab or a water professional narrow the cause quickly.
Summary
- Smell a glass of cold tap water and a glass of hot tap water.
- Clean the door seal, dispenser drawer, and drum, and let everything dry.
- Check the drain hose and refill the drain trap if it has dried out.
- Run an empty hot cycle and a cold cycle with a drum-cleaning product, then smell each one.
- If the tap water itself smells, test the supply before you keep cleaning the machine.