Answers / Problems & Symptoms

Washing Machine Leak or Odor

Urgency: Low Last updated September 24, 2026 · Monitor My Air

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Most likely causes, in order

1. Supply hose leak or failure (most common)
2. Drain hose or standpipe overflow
3. Internal machine moisture buildup
4. Floor drain or pan failure
5. Past leak with residual contamination

Washing machines handle more water than almost any other appliance in your home, a single load can use 15–30 gallons. So when something goes wrong, even a small leak adds up fast. And because most people don't look behind or under their washing machine very often, these problems can go unnoticed for months.

If you're smelling something musty or sour near your laundry area

• Front-load washers are notorious for this. The rubber door gasket (that big seal around the door opening) traps moisture, lint, and grime. Peel it back and look inside the folds, you'll often find dark mold and standing water. Wipe it down with a damp cloth and a little dish soap or hydrogen peroxide (3%). Make a habit of leaving the door cracked open between loads so it dries out. Some people also leave the detergent drawer slightly open.

• Top-load washers can also develop odor from standing water in the drum or around the agitator. Run an empty hot water cycle with 2 cups of white vinegar monthly to keep things fresh.

• If the smell is strongest near the FLOOR rather than inside the machine, moisture is probably getting underneath, that's a leak, not just an internal odor.

If you see water on the floor

• Check the supply hoses FIRST. These are the two hoses (hot and cold) that connect to the wall valves behind the machine. If they're the original rubber hoses and more than 5 years old, replace them immediately, rubber hoses are the #1 cause of catastrophic washing machine floods. Braided stainless steel hoses ($15–$25 for a pair) are much safer and last 8–10 years. This is one of the cheapest and most important upgrades you can make.

• Look at the drain. Your washer pumps water out through a drain hose that usually hooks into a vertical pipe in the wall (called a standpipe). If the standpipe overflows during the drain cycle, the pipe may be partially clogged, or the hose may be inserted too deeply. The drain hose should only go about 6–8 inches into the standpipe, and the standpipe itself should be at least 2 inches in diameter.

• Check for leaks at the hose connections. Feel around each connection point, where hoses meet the back of the machine and where they meet the wall valves. Tighten by hand or with pliers if you find dripping. If the hose fitting is corroded or won't seal, replace the hose.

Assessing the damage underneath

• Carefully slide the machine out (unplug it first, and turn off the water supply valves). Look at the floor. Is it damp? Discolored? Does it feel soft or spongy when you press on it? If the floor is solid and just a little dusty, great, no damage. If it's warped, stained, or soft, water has been sitting there and may have damaged the subfloor.

• If your washer is on a second floor (common in newer homes), pay extra attention. A leak on an upper floor can damage the ceiling below, and the stakes of a hose burst are much higher.

What's a drain pan and do you need one?

• A drain pan ($15–$30) sits underneath your washing machine and catches small leaks before they reach the floor. It's a simple plastic or metal tray. It won't save you from a burst hose, but it catches minor drips and gives you an early warning. Highly recommended if your washer is on an upper floor or on finished flooring.

When to call someone

• If the floor beneath the machine is soft, buckled, or water-damaged, you likely need subfloor repair. A handyman or contractor can assess this, repair typically runs $300–$1,000 depending on the area and how much material needs replacing.

• If water is appearing and you can't tell where it's coming from, a plumber can pressure-test the connections and drain ($100–$250).

• If you see mold on the walls or floor behind the machine, and it's more than a small surface patch, get a mold professional to evaluate, especially if the wall feels damp or soft. Inspection typically costs $250–$500.

• If your washer is on a second floor and you've found any leak, get it fixed promptly, water damage to the floor below can escalate costs quickly.

Related answers

• Carpet Smells Musty After Leak
• Mold Behind Cabinets

Education, not medical advice or a professional inspection of your property.