How do I clean a dishwasher that is not cleaning properly?

A dishwasher that has stopped cleaning well is almost never broken. Three consumables and maintenance items account for nearly every case: a blocked filter, blocked spray arms, and salt or rinse aid that ran out unnoticed.

What you'll need

• Warm soapy water
• Old toothbrush
• Dishwasher salt and rinse aid (optional)
• Cocktail stick (optional)

Step by step

1. Remove and clean the filter.Bottom of the machine, usually twisting out. Rinse under a tap and scrub with a brush. Do this monthly — it is the single most neglected part.
2. Clear the spray arm holes.Take the arms off if they unclip. Push a cocktail stick through each hole — limescale and debris block them, so water no longer reaches the top rack.
3. Check the arms spin freely.Spin them by hand. If a tall item is blocking them, nothing on that level gets cleaned regardless of anything else.
4. Top up the salt and rinse aid.Salt softens the water in machines that use it; rinse aid prevents spotting. Empty reservoirs are a very common cause of a sudden decline.
5. Run a hot empty cycle with a cleaner or white vinegar.It removes grease and limescale from the internals. Monthly is a reasonable frequency.
6. Wipe the door seal and the edges.Grease and debris accumulate there, cause smells, and prevent a good seal.
7. Review how you load it.Nothing blocking the arms, dirty faces towards the spray, no items nested inside each other, and do not overfill. Loading is a common cause of poor results.
8. Scrape but do not pre-rinse.Modern detergents need some soil to work against. Scrape off solids and leave the rest — heavy pre-rinsing genuinely makes results worse.

Tips

• Run the hot tap at the sink until it runs hot before starting the machine. It starts the cycle with hot water rather than cold.
• Use the correct detergent for your water hardness. In a hard water area, salt is not optional even with all-in-one tablets.
• White residue on glasses is usually limescale or too little rinse aid; cloudiness that will not wash off is etching, which is permanent.

Common mistakes

• Never cleaning the filter — It fills with food debris and the machine then recirculates dirty water over everything.
• Rinsing everything before loading — Modern detergents are formulated to act on soil. Over-rinsed loads actually come out worse, and it wastes water.
• Ignoring the salt light — Without salt in a hard water area, limescale builds up on the element and spray arms and performance drops steadily.

Questions people ask