Dishwasher Smells Like Mildew? Check These Fixes
Question: I just moved in, and my dishwasher smells like mildew.
The dishwasher looks fairly new. The filter is clean.
Also, when it is windy, my kitchen sink and shower smell a little.
Do you have any suggestions?
Answer: The smell may not be from the dishwasher itself. It may be coming from the drain, a dry trap, a vent issue, or a bad dishwasher drain hose setup.
Why A Clean Dishwasher Can Still Smell
A clean filter is a good sign.
But mildew smells can hide in other places.
Food film can sit inside the spray arms.
Grease can also build up in the drain hose.
Start by running a dishwasher cleaning cycle.
Use a dishwasher cleaner or white vinegar.
Do not mix cleaners with bleach.
Check the rubber door gasket next.
Wipe the folds with warm, soapy water.
Then leave the door cracked after each wash.
Check The Dishwasher Drain Hose
The drain hose should rise before it enters the sink drain.
This is called a high loop.
Some homes use an air gap instead.
A low hose can let dirty sink water flow back.
That can make the dishwasher smell bad.
You can read more about dishwasher air gaps from The Home Depot.
Windy Weather Is A Big Clue
The sink and shower smell during the wind is important.
That may point to a plumbing vent issue.
Wind can affect the air flow at the roof vent.
A blocked vent can also pull water from traps.
When traps lose water, sewer gas can enter.
The smell may seem like mildew or rotten drains.
Run water in every sink, tub, and floor drain.
This helps refill dry P-traps.
Also, check any unused basement drains.
Simple Checks Before Calling A Plumber
- Clean the dishwasher gasket and spray arms.
- Run a dishwasher cleaner cycle.
- Confirm the drain hose has a high loop.
- Run water in every drain for one minute.
- Look under sinks for loose trap parts.
- Check for slow drains or gurgling sounds.
If the smell returns during the wind, call a plumber.
Ask them to check the roof vent.
They should also inspect the drain traps.
A smoke test may help find leaks.
The EPA indoor air quality guide has more home air safety tips.
Sewer gas should not be ignored.
It can point to a real plumbing problem.
Fixing the vent or trap issue may stop every odor.
That includes the dishwasher, sink, and shower smells.
I’m Chris Mayer, writing for Plumbing 101.
