How to Clean a Dishwasher: Filter and Spray Arm Guide

Quick Answer

Cleaning a dishwasher involves removing food debris and mineral buildup to prevent odors and drainage issues. The most effective fix is to manually clean the filter and run a cycle with a specialized cleaner or vinegar.

A dirty dishwasher is usually a clogged filter or gunked-up spray arms, and honestly, most people have never cleaned either one. Ignore it long enough and you're looking at standing water, a machine that smells like a swamp, and dishes that come out dirtier than they went in. I see this constantly. Takes maybe 20 minutes to fix and costs you nothing.

GenericDishwasherSeverity: moderateDifficulty: intermediate75% DIY Success

Time to Fix

15–90 min

Difficulty

intermediate

Parts Cost

—

Tools Needed

Old toothbrush, White vinegar (2 cups)

What Does the HOW-CLEAN Code Mean?

OK so here's the deal: your dishwasher cleans itself, right? Wrong. That's the myth that causes all the problems. The filter at the bottom catches all the food junk, and if you never pull it out and rinse it, you're basically recirculating dirty water over your dishes every single cycle. Most people go years without touching it. Probably the most neglected maintenance task in the whole kitchen.

Common Causes

The mesh filter under the spray arm is packed with food particles and grease, so water can't drain properly and just recirculates through the same dirty water every cycle.
Spray arm nozzles are clogged with mineral deposits or a small piece of broken glass, so water doesn't reach the top rack at all.
Thick grease coating on the interior tub walls, usually from running lots of heavily soiled pots without pre-rinsing, trapping odors and reducing wash effectiveness.
Black mold growing in the door gasket folds, which is extremely common in humid climates or when the door is left closed while the machine is still wet inside.
Hard water scale has built up on the heating element and interior walls, leaving a white chalky film that transfers onto glassware and makes everything look dirty even after washing.
Food debris has settled into the drain sump at the very bottom of the tub, just past the filter housing, and it's sitting there rotting and causing that sulfur smell.

Symptoms You May Notice

Dishes come out with a gritty film or visible food particles still stuck to them even after a full cycle.
There's a standing puddle of water at the bottom of the tub after the cycle finishes, maybe half an inch deep.
You open the door and it hits you, that sour, musty, sometimes sulfur-y smell that means something's rotting in there.
Cloudy white film on glassware that won't come off no matter what, which is hard water mineral scale baked onto the glass.
The top rack dishes are consistently coming out dirty or still have dried soap on them because the upper spray arm nozzles are blocked.

Can you reset a Generic dishwasher to clear the HOW-CLEAN code?

For a basic reset after cleaning, open the door, press and hold the Start or Cancel button for 3 seconds until you hear a beep or the display clears. Then close the door and let it drain completely, usually takes about 90 seconds. After that, run one empty hot cycle to flush everything through before loading dishes again.

Tools Required for Diagnosis

Old toothbrushWhite vinegar (2 cups)Baking soda (1 cup)Small wire or toothpick (for spray arm holes)Dish soapOld rag or paper towelsFlashlight (to see into drain sump)

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

Frequently Asked Questions

How often should I actually clean my dishwasher filter?

Honestly? Once a month if you run it daily. Every two months if it's just you or a couple people. I know nobody does this, but the filter is the whole reason your dishes stop getting clean. Pulled one out last week that was so clogged it looked like wet felt. The homeowner had never touched it in three years. Clean filter equals clean dishes, it's basically that simple.

Can I use bleach to clean my dishwasher?

Depends on your machine. If you've got a stainless steel interior tub, skip the bleach entirely, it'll pit and discolor the steel over time. Plastic interior tubs can handle it in small amounts. For mold on the gasket, diluted bleach works great, just don't pour it into the main tub on a stainless machine. Stick with vinegar and baking soda for the tub itself, it works just as well and won't damage anything.

Why does my dishwasher smell like rotten eggs?

That sulfur smell is almost always food debris rotting in the drain sump or filter, specifically proteins like egg and meat breaking down. Pull the filter, clean it, then pour a cup of baking soda in the bottom and let it sit overnight before running a hot cycle. If the smell keeps coming back, check the drain hose where it connects to the garbage disposal or sink drain. Sometimes there's a food clog in there too, and it's easy to miss because you can't see it.

My dishes have white spots. Is that a cleaning problem?

That's hard water mineral deposits, specifically calcium and magnesium scale, and it's not a cleaning problem so much as a water chemistry problem. A good rinse aid helps a lot, like Finish Jet-Dry, because it changes how water sheets off the dishes. Also try running a citric acid cleaning cycle, you can buy dishwasher descaler at any hardware store for about $8-10. If your water is really hard, you might need to do this monthly.

How long does it take to fully clean a neglected dishwasher?

Start to finish? About 20-25 minutes of actual hands-on work, plus the time for the cleaning cycles to run. Filter and spray arms take maybe 10 minutes. Gasket scrub is another 5. Then two cleaning cycles run themselves while you do something else. So realistically you're looking at under 30 minutes of effort total. Way cheaper than a service call, and way less embarrassing than a repair tech opening your filter for the first time.

Do I need to use a special dishwasher cleaner or does vinegar work?

Vinegar works fine for regular monthly maintenance, honestly. The commercial cleaners like Affresh or Finish dishwasher cleaner are a little more effective on heavy grease and mineral buildup, and they're only about $5-7 for a pack of three tablets, so they're worth it for a really neglected machine. I usually tell people: use vinegar monthly, use a commercial cleaner every 3-6 months or when you notice odors coming back. Don't use both in the same cycle though.

Written by

Mike Sullivan

Lead Appliance Repair Technician · 20 years experience

Last verified for technical accuracy on March 17, 2026