"Dishwasher won't drain" is the third-most-common residential service call we run in LA — about 12 percent of dishwasher calls overall. Half of these resolve at customer-side diagnosis before the tech truck even rolls. This guide walks you through the priority order our techs use, so you can fix the cheap stuff yourself and only call when it's a real component failure.
BHGS #A49573, EPA 608 Universal certified #1346255700410. We service dishwashers across LA, Orange, Ventura, San Bernardino, Riverside. $89 residential diagnostic, applied toward repair.
Step 1: Check the garbage disposal — about 35 percent of "dishwasher won't drain" calls start here
Almost all residential dishwashers drain through the garbage disposal. The disposal has a knockout plug that's removed during dishwasher installation; if your disposal is partially clogged, the dishwasher drain backs up because the disposal can't accept the water flow.
The five-minute test:
- Run the disposal for 30 seconds with cold water. Does water drain freely from the sink?
- If no — disposal is partially clogged. Clear it (manual reset button at the bottom, ice cubes + cold water to grind, plumber's snake if needed).
- If yes — disposal is fine, move to step 2.
About 35 percent of dishwasher drain calls in LA resolve at the disposal. Especially common in homes with high-grease cooking — the grease accumulates at the disposal-to-drain trap junction.
Step 2: Check the drain hose — about 15 percent of calls
The drain hose runs from the dishwasher pump to the disposal (or to a separate drain stub on dishwasher-only sink installations). Two failure modes:
- Kink in the hose. If the dishwasher has been pulled out for service or the cabinet base has shifted, the hose can fold and restrict flow. Pull the dishwasher out gently (or look behind the kick plate) and inspect.
- Improperly-installed high loop. Code requires the drain hose to loop up to the underside of the counter before going down to the disposal. Without the high loop, dirty disposal water can siphon back into the dishwasher. Confirm there's a loop; if not, you need code-correct rerouting.
Step 3: Check the air gap (if installed) — about 10 percent
The air gap is the small chrome cylinder mounted next to the faucet on some installations (more common in older LA homes). It serves the same function as the high loop but as a code-required physical barrier. Air gaps clog with food debris over years.
How to clear: pull off the chrome cap, lift the inner plastic cap, inspect for debris. Clean with a brush and warm water. Reassemble. Five-minute fix.
Step 4: Check the dishwasher filter and sump
Most modern dishwashers (KitchenAid, Bosch, Miele, premium GE) have a removable cylindrical filter at the bottom of the tub. Pull it out, wash under running water, inspect the sump (the recess where it sits) for food debris or broken glass.
Older dishwashers have a coarse filter under the spray arm (usually metal mesh). Same procedure: remove, clean, reinstall.
About 10 percent of "won't drain" calls resolve at filter cleaning. The filter is supposed to be cleaned every 1-3 months on heavy use, every 6 months on light use. Most LA households we service haven't cleaned the filter in 1+ years.
Step 5: When to call us — drain pump failure
If the disposal is clear, the drain hose is unkinked, the air gap is clean, and the filter is clean, you're looking at drain pump failure. Year 5-8 typical wear. Symptom: motor hums when the cycle reaches drain phase but no water moves out, or motor runs silently with no flow.
Drain pump replacement is in our $280-$440 typical range, depending on brand. Bosch, KitchenAid, Miele drain pumps are slightly more expensive than Whirlpool, GE, Frigidaire. We carry common pumps on the truck for same-day repair on most calls.
Quick reference: the priority order in summary
| Step | Cost / Effort | % of calls |
|---|---|---|
| 1. Garbage disposal cleared | 5 min, free | ~35% |
| 2. Drain hose kink check | 10 min, free | ~15% |
| 3. Air gap cleared | 5 min, free | ~10% |
| 4. Filter cleaned | 10 min, free | ~10% |
| 5. Drain pump replacement | $280-$440 turnkey | ~30% |
If steps 1-4 don't fix it
Call us. $89 residential diagnostic includes the drain pump test, control board diagnostic, and inlet valve check. If the diagnostic identifies the drain pump, the $89 is applied toward the $280-$440 repair total when you approve the work.
For service: dishwasher repair. Hard-water angle: LA hard water killing dishwasher. By city: Los Angeles, West Hollywood, Beverly Hills, Pasadena.