Why Is Your Dishwasher Not Cleaning Properly? Common Causes
updated 11 July 2026
Quick answer
A dishwasher usually stops cleaning well because a clogged filter and blocked spray arms don't let enough water through, or because the dishes are loaded in a way that stops the rotating arms. Add to that a program temperature that's too low, missing salt and rinse aid with hard water, and weak tablets. Start by cleaning the filter and the arms, then fix the other things one at a time.
Step by step
- 1
Clean the filter and spray arms
Take the filter out of the bottom of the tub and rinse it under running water, removing food scraps and grease. Remove the lower and upper spray arm, poke clogged nozzles clear with a toothpick, and rinse them under the tap. This is the most common cause, because dirty water and a weak spray simply can't get dishes clean.
- 2
Load dishes so they don't block the arms
Check by hand that the lower and upper arm rotate freely - a tall pot or a cutting board often stops them. Place dishes dirty side down and facing the center, don't stack them on top of each other, and don't hide small cutlery behind large items. Angle cups and bowls so water doesn't collect in them.
- 3
Pick a hotter program
Eco and short programs wash at lower temperatures and are designed to save power and water, not to handle dried-on grime. For heavily soiled dishes choose a 60-70°C (140-158°F) or intensive program. Dried-on grease and starch only dissolve at higher temperatures.
- 4
Top up the salt and rinse aid
With hard water, a lack of dishwasher salt leaves a white film and limescale on the dishes and weakens the wash. Refill the salt reservoir in the bottom of the tub and pour rinse aid into the dispenser in the door. Even all-in-one tablets don't fully replace salt when the water in your area is very hard.
- 5
Switch to better tablets
The cheapest tablets often lack the enzymes that break down grease and starch, so dishes come out dull and half-washed. Try proven all-in-one tablets and put them in the closing dispenser, not loose on the bottom. A tablet tossed onto the floor of the tub dissolves too early and loses its power during the main wash.
- 6
Check the circulation pump
If the filter, the arms, the program, and the detergent are all fine and dishes still come out dirty, the circulation pump that pushes water to the arms may be weakening. The telltale signs are a quieter-than-usual spray and lukewarm water despite a hot program. That's a repair for a service technician, because it requires taking the dishwasher apart.
When a worn pump or heater is to blame
If you've gone through the filter, the loading, the program, and the detergent and results don't improve, the cause sits deeper. A weak circulation pump can't push water with enough force, so the arms barely turn and dishes in the top rack stay dirty. A failed heating element, in turn, doesn't heat the water, and then even a good program washes with lukewarm water.
You'll recognize it when the dishes come out not just dirty but also cold and wet at the end of the cycle. A repair service will diagnose and replace a fault like that, because it requires access to the components under the tub. Before you call a technician, though, make sure the cheaper causes really have been ruled out.
Why the dishwasher won't fill with water
If the dishes are completely dry and dirty and the program ends too quickly, the problem isn't poor washing but no water at all. Start by checking that the supply valve at the tap is open and the inlet hose isn't kinked. A closed valve or a clogged mesh screen at the hose inlet is the most common reason a dishwasher won't take in water.
Also check the mesh filter where the hose connects to the valve, because limescale and dirt build up on it. If the supply is clear and water still won't flow in, the solenoid valve inside the dishwasher may have failed. That calls for a service visit.
Frequently asked questions
›Why does my dishwasher leave dishes dirty despite good tablets?
Even the best tablet won't help when the filter is clogged and the arms are blocked, because dirty water just keeps circulating. Also check that the dishes aren't blocking the arms and that the program isn't too cool. Only with a clear water path and hot water can the tablet do its full job.
›Does the eco program clean worse?
Eco washes at a lower temperature and takes longer to save power, so it copes worse with heavily soiled dishes. For everyday, lightly soiled loads it's enough. Dried-on grease and burnt residue come off better on a 60-70°C program.
›Why is there a white film left on my dishes?
A white film is most often limescale from hard water and a lack of dishwasher salt. Top up the salt in the reservoir and the rinse aid in the dispenser, and the film should disappear. If it stays anyway, check whether the water hardness setting matches the hardness in your area.
›Why won't the dishwasher fill with water?
The usual culprit is a closed valve at the tap or a kinked or blocked inlet hose. Also check the mesh screen at the hose inlet, because dirt and limescale collect there. If the supply is clear and water still won't come in, a failed solenoid valve is often the cause.
›How often should I clean the dishwasher filter?
Rinse the filter once a week, or even more often if you regularly wash heavily soiled dishes. It takes a moment and prevents poor washing and unpleasant smells. Once a month, also run an empty, hot cycle with citric acid.