I ran the same load of dishes three times once. Three cycles. The plates still came out with oatmeal crusted in the corners and a weird film on the glasses. I was ready to call a repair person, which in my area starts at a hundred bucks just to show up.

Then I actually looked inside the dishwasher. What I found was disgusting, and also completely fixable in about 15 minutes with zero tools and zero dollars.

Clean the Filter (Yes, There Is a Filter)

Most people do not know their dishwasher has a filter. It does. It lives at the bottom of the tub, under the lower spray arm. Twist it out (usually a quarter turn) and prepare to be horrified. Mine looked like a science experiment — grey sludge, bits of food, and what I am fairly sure was a piece of a sticker from a produce label. Rinse it under hot water and scrub with an old toothbrush. If the filter is clogged, water cannot circulate properly. This fixes about 60% of cleaning problems.

Check the Spray Arms for Clogs

The spray arms have tiny holes that shoot water onto your dishes. Those holes clog with mineral deposits and food particles. Pull the arms off (they typically snap or twist off) and hold them under a faucet. Water should stream out of every hole. Clogged ones will dribble or do nothing. Use a toothpick or paper clip to clear each hole. I had three completely blocked holes on my upper arm — no water was hitting the top rack at all.

Load Dishes the Right Way

If the spray arms cannot spin, nothing gets clean. Do not block them with tall pots or cutting boards in the lower rack. Angle bowls downward so water does not pool. Glasses on the top rack go between tines, not on top of them — they can flip and fill with dirty water. Plates face the center. This sounds obvious until you realize you have been loading it wrong for years. I definitely was.

Use the Right Detergent and Amount

Powder or gel detergent can leave a white film if your water is hard. Switch to pods or tablets — they include water softeners and rinse aids. Too much detergent is as bad as too little; residue attracts dirt. And make sure the detergent dispenser door opens fully during the cycle. If a pan or tall item blocks it, the detergent never releases.

Run Hot Water First

Before starting the dishwasher, run the kitchen sink tap until the water is hot to the touch. Dishwashers pull from the same hot water line, and if the first burst of water is cold, the pre-wash cycle does nothing. This one change improved my cleaning results immediately — I tested it side by side and it was not subtle.