Dishwasher Not Cleaning or Not Draining? Here's the Real Cause

Two complaints make up the bulk of our dishwasher calls across Los Angeles: dishes coming out dirty or filmy, and water sitting at the bottom of the tub after a cycle finishes. Both look like they could be a major motor or pump failure. Most of the time, they aren’t.

Dishes Not Getting Clean: Check the Filter First

This is the most common dishwasher complaint we see, and it’s rarely the wash arms or the motor.

What’s actually happening: Modern dishwashers — especially European brands like Bosch and Miele — don’t have a self-cleaning grinder like older American models did. Instead, they rely on a fine mesh filter at the bottom of the tub that traps food debris. When that filter clogs, water can’t circulate properly through the spray arms, and dishes come out greasy, filmed, or with visible food residue.

How to check it: Most filters twist and lift straight out of the bottom of the tub — no tools required. Rinse it under warm water and use a soft brush (an old toothbrush works fine) on the fine mesh screen. This takes about three minutes and is, by a wide margin, the single biggest fix for poor cleaning performance.

If the filter is clean and dishes still aren’t clean, check these next:

• Water temperature — the water entering the dishwasher should be at least 120°F. If your water heater is set low or the kitchen sink hasn’t been run hot first, cold fill water won’t dissolve detergent properly.
• Spray arm rotation — spin each spray arm by hand. If it doesn’t move freely, food debris or a mineral deposit is likely blocking it.
• Detergent dispenser — check that it’s actually opening and emptying during the cycle. A dispenser that’s stuck closed means the detergent never even enters the wash.

Not Draining: Three Places to Look

Water sitting at the bottom of the tub after a completed cycle points to one of three things.

1. Clogged filter or drain path. Same filter mentioned above — when it’s packed with debris, water can’t make it back to the drain pump efficiently.

2. Kinked or blocked drain hose. The hose connecting the dishwasher to your garbage disposal or drain standpipe can kink during installation or become blocked with buildup over time.

3. Failed drain pump. If the filter is clean and the hose isn’t kinked, the drain pump itself may have failed — either the motor or the impeller. On Bosch units specifically, the drain pump is a frequent failure point, but the part is well-sourced and this is usually a same-day repair.

A quick test: Run a drain-only cycle (most dishwashers have one) and listen at the base of the unit. A healthy pump has a consistent hum. Silence, or a hum with no actual water movement, points to pump failure.

Leaking Is a Different Problem — Check These Instead

If your issue is water on the floor rather than water in the tub, the cause is usually one of: a worn door gasket (most common), a failed water inlet valve, or a cracked pump housing on an older unit. We cover this in more detail on our Dishwasher Repair page.

Why Hard Water Makes Both Problems Worse

Los Angeles has moderately hard water, and mineral sediment accumulates in the water inlet valve screen over time. A partially blocked inlet valve means the dishwasher runs through a full cycle without enough water actually entering the tub — which looks exactly like a “not cleaning” problem but is really a “not filling” problem. If your dishwasher seems to be skipping water fill or the cycle finishes unusually fast, this is worth checking before assuming the pump or motor has failed.

DIY Difficulty by Repair

Issue	DIY Rating	Notes
Clogged filter	Easy	No tools needed, 3 minutes
Spray arm blockage	Easy	Twist off, rinse, reattach
Kinked drain hose	Easy–Moderate	Requires pulling the unit out slightly
Drain pump replacement	Moderate–Hard	Requires disassembly, part sourcing by model
Door gasket replacement	Moderate	Straightforward but fiddly
Water inlet valve	Moderate	Requires water shutoff

When to Call a Tech

• You’ve cleaned the filter and checked water temperature, and dishes are still coming out dirty
• Water is still sitting in the tub after checking the filter and drain hose
• You have a Bosch or Miele unit and suspect a pump or control board issue — these use proprietary parts and diagnostics
• The dishwasher is leaking, not just failing to drain

We do dishwasher repair throughout Los Angeles, including dedicated service in Los Angeles. The $85 diagnostic fee is applied toward your repair when you approve the work. Call (323) 806-3039.