Dishwasher Not Cleaning Dishes

Common Causes

Grit on dishes almost always means dirty water is recirculating through a clogged filter. A top rack that cleans poorly points at the upper spray arm — blocked holes or a weak pump that cannot push water that high. A half-dissolved tablet means the dispenser opened late, the water was not hot enough, or the tablet fell onto a blocked door. White film is usually hard water or detergent dosing rather than a mechanical fault.

Why a Dishwasher Stops Cleaning Well

Dishwashers reuse the same few liters of water throughout a cycle, cleaning it continuously through a filter at the bottom of the tub. When that filter clogs with food and grease, the machine sprays dirty water back over the dishes — which is exactly what gritty plates and cloudy glasses look like.

The spray arms do the mechanical work. Their small holes clog with food particles and hard water scale, weakening or misdirecting the spray. The upper arm suffers first because it depends on full pump pressure — a weak circulation pump or blocked arm shows up as a dirty top rack while the bottom rack still cleans.

Temperature and detergent round out the picture. Wash water should enter at around 120°F; cooler water dissolves detergent poorly and cuts grease badly. A dispenser that opens against a blocked door drops its tablet too late in the cycle, leaving detergent half-dissolved and dishes half-cleaned.