How do I load a dishwasher properly?

A dishwasher does not scrub. It fires jets of detergent solution from rotating arms and relies on those jets hitting every soiled surface directly. Almost every complaint about a machine that does not clean is a loading problem: something shadowed something else, or something stopped an arm turning. The rules below all come from that one mechanism.

Step by step

1. Scrape, but do not rinse.Take off bones, skins, stickers and large lumps. Leave the residue. Modern detergent enzymes need soil to work on, and many machines have a turbidity sensor that runs a shorter, weaker cycle if the water stays clean.
2. Load plates in the lower basket, all facing the centre.The lower arm sprays upwards and outwards from the middle, so the dirty face of every plate should point inwards and downwards towards it. Plates all facing the same way, evenly spaced, never nested.
3. Put pans, casserole dishes and mixing bowls at the sides, tilted.Face down and angled so water can drive in and drain out. A bowl sitting flat traps a pool of dirty water that then floods everything below it when you unload.
4. Keep everything below the height of its own basket.This is the rule people break. A tall item in the lower basket catches the middle spray arm and stops it turning, and everything in the upper basket then comes out dirty. Chopping boards and baking trays go down the sides, never across the middle.
5. Cups, glasses and small bowls face down in the upper basket.The upper arm sprays upwards into them. Anything the right way up fills with dirty water. Angle glasses slightly rather than sitting them dead flat, so water runs off the base rim rather than pooling in it.
6. Space glasses so they cannot touch each other.Glass against glass under water pressure is how the rim chips. Use the stem clips if the basket has them, and leave a finger's width between anything fragile.
7. Mix cutlery handle-down in the basket, or lay it flat in the top drawer.In a basket, mix knives and forks and spoons rather than grouping them, so they do not nest and shield each other. Knives go handle-up as a safety rule; everything else handle-down so the dirty end faces the spray. In a flat third rack, spread everything out with space between pieces.
8. Keep plastics on the top basket only.The heating element and the hottest air are at the bottom. Plastics in the lower basket warp, and light plastics anywhere will flip over during the cycle unless they are held by a clip or weighted down.
9. Check nothing is blocking the detergent dispenser flap.The flap springs open partway through the cycle. A tall item or a plate leaning against it holds it shut, the tablet never releases, and the whole load comes out unwashed.
10. Spin both spray arms by hand before closing the door.Two seconds, every single time. If either one catches, move whatever it caught on. This single habit prevents most poor wash results.

Tips

• Load the machine as the day goes on, but run a cold pre-rinse programme rather than rinsing plates under a hot tap — it uses a fraction of the water.
• Unload the bottom basket first. Water pooled in upside-down cups in the top basket runs down onto clean dry plates otherwise.
• If one specific area comes out dirty every time, that tells you which spray arm is obstructed or which of its holes is blocked. It is a map, not bad luck.
• A very full machine cleans better than a half-full one run twice, so long as nothing overlaps. Overfilling only fails when items shadow each other.

Common mistakes

• Pre-rinsing everything under the tap — It wastes far more hot water than the machine uses, and on sensor machines it actively makes results worse by convincing the machine the load is clean.
• Nesting spoons and bowls — Two identical shapes stack together and the inner surface never sees water. Mixing cutlery types in the basket exists solely to stop this.
• Laying a baking tray flat across the lower basket — It blocks the middle spray arm completely and turns the entire upper basket into a rinse-only zone. Trays go vertically down the side.

Questions people ask