How often should you descale a dishwasher?
Updated July 2026
Run a dishwasher-cleaner or plain white-vinegar cycle once a month, and step up to every two weeks if you have hard water (7+ grains per gallon) or run the machine daily. Descaling clears the limescale, grease film, and biofilm that coat the spray-arm jets, the filter, and the tub. Left alone, mineral scale plugs those tiny jets so glasses come out cloudy and gritty, and the trapped food breeds the sour smell that greets you when the door opens.
What changes the interval
| Your situation | Interval | Why |
|---|---|---|
| Soft or softened water | Every 4–6 weeks | A softener strips most of the minerals that become scale |
| Hard water (7+ grains), no softener | Every 2 weeks | Limescale rebuilds on the jets and heating element fast |
| Daily use, big household | Every 2–3 weeks | More cycles mean more grease and food film per week |
| Glasses come out cloudy or filmy | Descale now | Scale on the jets is the usual cause, not your detergent |
| Musty or eggy smell on opening | Descale and clean filter now | Biofilm in the filter and sump is rotting trapped food |
| Light use or vacation home | Every 2–3 months | A machine that rarely runs builds scale slowly |
The cost of skipping it
What skipping it costs: scale and grease first show up as cloudy glassware and weak cleaning, then as a clogged filter and drain that leave standing water in the bottom. A saturated biofilm can jam the drain pump or foul the water inlet, a $150–350 repair, and chronic scale on the heating element shortens the machine's typical 9–12 year life. A new dishwasher installed runs $450–1,000. A jug of white vinegar is about $4 and a box of cleaner tablets $6–10, so a year of descaling costs less than one service call.
How to do it (5 minutes hands-on · one wash cycle · DIY)
- Pull the bottom rack and scrub any gunk out of the filter under the lower spray arm (twist it out and rinse under the tap).
- Check the spray-arm holes for lodged debris and poke clogged jets clear with a toothpick.
- Wipe the door gasket and edges where grease and food collect.
- Place a dishwasher-safe cup with 2 cups of white vinegar on the top rack, or drop a cleaner tablet on the floor of the tub.
- Run the hottest, longest cycle empty, then sprinkle baking soda on the floor and run a short rinse to freshen and brighten.
Knowing the interval is the easy half. OnOtto reminds you at the right interval, and it won't let you snooze it into next year. Tasks persist until they're done, and completing dishwasher descaling schedules the next one automatically.
Put this on autopilot, free for 30 daysFrequently asked questions
Vinegar or a commercial dishwasher cleaner?
Both work, and they target different things. White vinegar is a mild acid that dissolves limescale and hard-water film for pennies, and 2 cups on the top rack handles routine monthly descaling. Purpose-made tablets (Affresh, Finish, and similar, about $6–10 a box) also cut baked-on grease and sanitize, which vinegar does less well. A practical rhythm: vinegar most months, and a cleaner tablet every second or third month if you cook greasy food or have very hard water.
Do I still need to clean the filter separately?
Yes. Modern dishwashers have a removable filter under the lower spray arm that catches food, and it needs a rinse on its own schedule, weekly to monthly depending on how dirty the dishes go in. Descaling flushes the tub and jets but will not lift the packed food from a neglected filter. See how often to clean a dishwasher filter for that routine, which pairs naturally with the monthly descale.
Why are my dishes cloudy even after descaling?
Two culprits beyond scale. First, etching: a permanent cloudiness on glass caused by soft water plus too much detergent, which descaling cannot reverse. Second, a spent rinse aid, which is what sheets water off glass so it dries spot-free. Refill the rinse-aid dispenser, cut your detergent dose if your water is soft, and make sure the incoming water reaches about 120°F so the detergent dissolves fully.
Does a smelly dishwasher mean it is failing?
Rarely. A sour or eggy odor is almost always trapped food rotting in the filter, sump, or drain hose, not a dying machine. Clean the filter, run a hot vinegar cycle, and confirm the drain hose has a high loop so dirty water cannot sit in it. If the smell returns within days and the machine also drains slowly, then look at a partial clog or the drain pump. Track the descale date in your maintenance checklist so it does not slip.