TL;DR
Deep cleaning a washer drum is a hot empty cycle plus about ten minutes of hand scrubbing, and it works better with oxygen bleach than with harsh chemistry. Run the machine empty on its hottest setting with an oxygen bleach booster, scrub the areas water never reaches, and repeat monthly. Skip the drum entirely if the odor is coming from the gasket -- that is a different job.
What actually builds up in a drum
Three things accumulate on the inside of a washer tub, and they need different handling.
Soap and softener residue. Detergent that never fully rinses, plus the waxy coating fabric softener is designed to leave behind, forms a sticky film on the stainless drum and, more importantly, in the outer tub you cannot see.
Biofilm. That film feeds bacteria and mold, which is what produces the sour, musty smell.
Mineral scale. In hard water areas, calcium and magnesium deposit as a chalky white crust on the heating element and the drum. Roughly 85 percent of U.S. homes have hard water to some degree. Source: U.S. Geological Survey
An empty hot cycle handles the first two well. Scale needs a different approach, covered in hard water scale in a washing machine.
How do you deep clean a washer drum?
Run the machine empty on the hottest and longest cycle it has, with an oxygen bleach booster added directly to the drum. When it finishes, scrub the drum lip, the underside of the top loader agitator or the front loader gasket, and the door glass by hand. Wipe dry and leave it open.
Start somewhere else
If you came here because the machine smells, clean the door boot before the drum. The overwhelming majority of front loader odor lives in the gasket fold, not on the drum surface, and a tub cycle will not touch it. Clean the door gasket first, then come back.
For a top loader, the equivalent spot is the underside of the lid, the rim above the water line, and the top edge of the tub.
The hot empty cycle, step by step
1. Empty the machine completely. No towels, no "one small load while I am at it." The point of the cycle is high water volume with nothing absorbing it.
2. Add oxygen bleach to the drum, not the dispenser. Oxygen bleach is sodium percarbonate. In hot water it releases hydrogen peroxide, which lifts organic film over a period of minutes to hours rather than seconds. It is color safe and gentle on rubber and stainless. How to use oxygen bleach at home covers dosing.
3. Choose the hottest, longest cycle. Many machines have a dedicated tub clean or sanitize cycle. If yours does not, use a heavy duty cycle at the maximum temperature with an extra rinse.
4. Pause it midway if you can. Letting the drum soak for thirty to sixty minutes partway through gives the oxygen bleach time to work. Some tub clean cycles already build in a soak.
5. Let it finish and drain fully.
Now do the parts water never reaches
The cycle handles submerged surfaces. These need hands.
- The drum lip and the front rim, where residue collects above the water line.
- The door glass, inside and out, and the metal frame around it.
- The underside of a top loader lid and the plastic rim beneath it.
- The bleach and softener dispenser cups, which are separate from the drum.
- The base of a top loader agitator, if it lifts out.
Hot water with a drop of dish soap on a cloth handles almost all of it. For stubborn film, a paste of oxygen bleach and a little warm water, left to sit for fifteen minutes, does the rest.
Skip these
Do not use a scouring pad or powdered abrasive on a stainless drum. Scratches hold residue and make the next cleaning harder.
Do not combine cleaners. One product per cycle. Bleach plus any acidic descaler releases chlorine gas -- see never mix bleach and vinegar. Bleach with an ammonia-containing cleaner releases chloramine. Ventilate the room whenever you use a chlorine product.
Do not run bleach cycles constantly. Chlorine bleach dries rubber components over time. Once in a while for a badly neglected machine is fine; monthly is not.
How often, honestly
Once a month is the right rhythm for most households. Move to every two or three weeks if you wash a lot of heavily soiled clothing, wash pet bedding, live with hard water, or use fabric softener regularly.
If the machine has never had this done, expect two cycles back to back the first time. Years of residue does not leave in one pass.
Preventing buildup beats cleaning it
The cheapest deep clean is the one you do not need. Dose detergent to the actual load size rather than filling the cap, use detergent formulated for your machine type, cut back on fabric softener, move wet loads out promptly, and leave the door and dispenser drawer ajar so the machine dries. That set of habits, plus a full washing machine cleaning routine once a month, keeps a drum clean indefinitely.
FAQ
Does a tub clean cycle actually do anything?
Yes, but only for surfaces the water touches. A tub clean cycle runs hotter, longer and at a higher water level than a normal wash, which flushes residue out of the outer tub. It cannot clean the gasket fold, the dispenser housing or the drain pump filter, which is why those need hands.
Can I use vinegar to clean my washer drum?
Vinegar helps with light mineral scale but does little against soap film and biofilm, which are the usual problems. It also should never share a cycle with any chlorine product. For general drum cleaning, oxygen bleach in a hot cycle is more effective.
Should I use bleach or oxygen bleach in the washer?
Oxygen bleach for routine monthly cleaning, because it is gentle on rubber and stainless and works over time on organic film. Chlorine bleach only occasionally, for a badly neglected machine, used alone with the room ventilated and never mixed with another product.
Why is there black residue flaking off inside my drum?
Flaking black material is usually biofilm breaking loose from the outer tub or the gasket, often after the first deep clean. Run a second hot empty cycle and wipe the drum. If it keeps appearing, the source is likely the outer tub and needs repeated cycles over a few weeks.
How do I clean a top load washer drum?
The same way. Fill it on the hottest setting, add oxygen bleach, let it agitate briefly and then soak, and finish the cycle. Then scrub the rim, the underside of the lid, and the base of the agitator, since those sit above the water line.
Will cleaning the drum stop my clothes from smelling?
Only if the drum was the source. Clothes that smell sour after washing usually point at a wet load left sitting, a gasket full of film, or too much detergent leaving residue in the fabric itself. Fix those and the smell goes away.
For the whole-home version of this work, see house cleaning services.
If the laundry room has gotten past the point where an hour fixes it, that is a reasonable thing to hand off. Every home is different, so the real number depends on size, condition, and what you want covered. Get a quote and we will walk you through it.