How to Descale a Dishwasher

Dishwashers accumulate mineral scale the same way kettles do, only you can't see it happening. Hard water leaves calcium and lime deposits on the heating element, inside the spray arm jets, and across every surface the water touches. Over time, these deposits reduce water flow, make the machine work harder, and leave a chalky film on supposedly clean dishes. A proper descaling every three to six months strips away this buildup and restores the machine to something close to its original performance. The process takes less time than a standard wash cycle and uses supplies you likely already have.

1. Spot the Scale Problem. Remove all dishes, utensils, and racks. Check the bottom filter area for food debris, bone fragments, or buildup that could block drainage during descaling. Pull out the bottom spray arm if it lifts free and examine the spray holes — white crusty deposits here mean you're working on the right problem.
2. Unclog the Filter First. Twist and remove the cylindrical filter at the bottom of the tub. Rinse it under hot water while scrubbing with an old toothbrush to dislodge trapped particles. If the mesh is clogged with white deposits, soak it in a bowl of white vinegar for 15 minutes, then scrub again. Reinstall the filter securely before proceeding.
3. Dissolve the Buildup. Place two cups of white vinegar in a dishwasher-safe bowl or measuring cup on the top rack. Run the hottest, longest cycle available without detergent. The vinegar will vaporize and circulate through the spray arms, dissolving calcium deposits throughout the system. Let the cycle complete fully.
4. Scrub Away Remaining Deposits. Open the door and while everything is still warm and damp, use a stiff brush or old toothbrush dipped in straight vinegar to scrub any remaining white buildup around the door gasket, on the heating element, and along the bottom edges. The acid will have softened the scale, making it easier to remove mechanically.
5. Clear Every Spray Hole. Remove both spray arms by twisting or unclipping them. Use a toothpick or straightened paperclip to clear each spray hole, pushing through any mineral deposits. Rinse the arms under running water while flexing them gently to dislodge internal debris. Reinstall with spray holes facing down.
6. Neutralize and Deodorize. Sprinkle one cup of baking soda across the bottom of the empty dishwasher. Run a short hot cycle. This neutralizes any remaining vinegar, absorbs lingering odors, and gives the interior a final polish. The combination of acid followed by base removes both scale and any discoloration.
7. Restore Smooth Surfaces. Open the door and use a microfiber cloth to wipe down the interior surfaces, door gasket, and edges while everything is damp. Check that the spray arms spin freely by giving them a manual rotation. Replace the racks and run your hand along surfaces that were previously rough — they should feel noticeably smoother.