Standing water in your dishwasher is more than an inconvenience — it breeds bacteria and can damage the pump seal over time. Here are the 6 most common causes ranked from easiest to hardest, what each one costs to fix in Los Angeles, and which ones you can handle yourself.
When your dishwasher won't drain, it is tempting to assume the worst. But in most cases, the fix is straightforward and far less expensive than a replacement. At A&Y Appliances, we handle dishwasher repair calls across Los Angeles and Ventura County every day — and roughly half of all drain-related issues fall into the first two categories below, both of which are inexpensive to resolve.
Most dishwashers drain through the garbage disposal. If the disposal is clogged, has food packed in the drain connection, or if the knockout plug was never removed during installation, water backs up into the dishwasher tub. This is the single most common cause of a dishwasher not draining, and it has nothing to do with the dishwasher itself.
How to check: Run the garbage disposal with water flowing for 15-20 seconds to clear it. If the disposal grinds but water does not drain, the clog is further down the line. If your disposal was recently installed or replaced, check that the installer removed the knockout plug from the dishwasher inlet port — this is a surprisingly common oversight.
DIY fix: Yes. Run the disposal thoroughly. If that does not clear it, disconnect the dishwasher drain hose from the disposal inlet and check for blockage. A flashlight and a long bottle brush can clear most obstructions.
Professional cost: $85-$150 (typically just the diagnostic fee if the fix is straightforward).
Every dishwasher has a filter or screen at the bottom of the tub that catches food particles before they enter the drain pump. When this filter is clogged with grease, food debris, broken glass, or label residue, water cannot flow through to the pump. Many homeowners do not realize this filter exists or that it needs regular cleaning.
How to check: Remove the bottom rack. Look at the base of the tub — you will see a cylindrical filter or a flat screen near the drain area. Twist and lift it out. If it is coated in greasy residue or packed with food particles, this is your problem.
LA factor: Los Angeles has some of the hardest municipal water in the country at 12-16 grains per gallon. This mineral-heavy water leaves calcium scale deposits on the filter mesh that trap food particles more aggressively than in soft-water areas. We recommend cleaning your dishwasher filter every two weeks if you run the machine daily.
DIY fix: Yes. Remove the filter, scrub it under hot running water with a soft brush and dish soap. Use white vinegar to dissolve mineral deposits. Reinstall and run an empty hot cycle.
Professional cost: $85-$150 (diagnostic fee covers cleaning and inspection).
The drain hose connects the dishwasher pump to the garbage disposal or sink drain. It runs behind or beneath the dishwasher and can become kinked when the unit is pushed back after installation or maintenance. Over time, grease and food residue also build up inside the hose, gradually narrowing the passage until water can no longer drain at full speed.
How to check: Pull the dishwasher forward enough to see the drain hose. Look for sharp bends, pinches where it passes through the cabinet wall, or visible swelling that indicates a clog inside. The hose should form a high loop near the countertop or connect to an air gap fitting — if it runs straight from the dishwasher to the disposal without a high loop, water can siphon back into the tub.
DIY possibility: Moderate. Straightening a kink is simple. Cleaning a clogged hose requires disconnecting it from both ends, which involves pulling the dishwasher out and working under the sink. If the hose is cracked or brittle, replace it entirely.
Professional cost: $120-$200 for hose replacement including parts. A&Y carries universal and OEM drain hoses on our trucks for same-day repair across Glendale, Burbank, and Pasadena.
The drain pump uses an impeller to force water out of the dishwasher tub and through the drain hose. When the pump motor burns out or the impeller breaks, water remains in the tub after every cycle. You may hear a humming sound during the drain phase (the motor trying but failing) or complete silence where you would normally hear draining.
How to check: Start a cycle and listen during the drain phase (usually the last 2-3 minutes). A working drain pump produces a steady whirring sound. If you hear a loud buzzing, grinding, or nothing at all, the pump motor or impeller is likely the issue. Broken glass or debris caught in the impeller can also jam the pump — a common problem when a wine glass breaks during a cycle.
LA factor: Hard water scale builds up on the pump impeller over time, reducing efficiency. In severe cases, scale freezes the impeller in place and burns out the motor. Running a dishwasher cleaner (citric acid based) once a month helps prevent this.
Professional cost: $180-$300 for drain pump replacement. This repair requires removing the dishwasher and accessing the pump assembly from underneath.
The check valve (also called a backflow preventer) sits in the drain path and allows water to flow out but prevents it from flowing back in. When this valve gets stuck in the closed position — often from grease buildup or hard water scale — water cannot exit the tub even though the drain pump is working correctly. When it gets stuck open, dirty water from the drain line flows back into the tub between cycles.
How to check: If the drain pump sounds like it is running normally but water is not leaving the tub, the check valve is a likely suspect. If you find dirty water in the tub when you have not run a cycle, the valve may be stuck open.
DIY possibility: Low. The check valve is typically located inside the pump assembly or at the drain hose connection point and requires disassembly to access.
Professional cost: $150-$250 including parts. The valve itself is inexpensive, but labor to access and replace it accounts for most of the cost.
The electronic control board manages every phase of the wash cycle, including sending voltage to the drain pump at the appropriate time. If the control board fails or a relay on the board burns out, the drain pump never receives the signal to run. The dishwasher completes the wash and rinse phases normally but skips or cuts short the drain phase entirely.
How to check: If the dishwasher runs a full cycle but never attempts to drain (no pump sound at all during the drain phase), and the pump is confirmed working, the control board is the likely cause. Some models display an error code — check your owner's manual. Power surges are a common cause of board failure, and LA's aging electrical grid makes this more frequent than you might expect.
DIY possibility: No. Control board diagnosis requires testing relay outputs with a multimeter, and replacement involves reprogramming on some brands.
Professional cost: $250-$450 depending on the brand and board availability. High-end brands (Miele, Thermador, Bosch) tend to run on the higher end due to parts cost.
Los Angeles municipal water measures 12-16 grains per gallon of hardness — well above the national average of 3-7 grains. This mineral-heavy water deposits calcium and lime scale inside every component the water touches: the drain filter mesh, check valve flap, pump impeller, and the interior of the drain hose. Over months and years, scale narrows drain passages and creates rough surfaces that trap food particles and grease.
For dishwashers in the LA area, A&Y recommends three preventive steps: clean the drain filter every two weeks, run a citric acid dishwasher cleaner once a month, and use a rinse aid to reduce mineral deposits on internal surfaces. These simple habits can prevent the majority of drain-related failures we see across Glendale, Pasadena, Burbank, and the rest of LA County.
| Issue | Cost (LA Area) | DIY Possible? |
|---|---|---|
| Clogged garbage disposal connection | $85 - $150 | Yes |
| Blocked drain filter / basket | $85 - $150 | Yes |
| Kinked or clogged drain hose | $120 - $200 | Moderate |
| Failed drain pump motor | $180 - $300 | No |
| Check valve stuck or broken | $150 - $250 | No |
| Control board (drain relay) | $250 - $450 | No |
All repairs at A&Y start with an $85 diagnostic fee applied toward the repair total. Written estimate before any work begins. OEM parts with a 1-year warranty on parts and labor.
Before calling for service, try these steps in order. They solve the problem roughly 40% of the time:
1. Run the garbage disposal. Run it for 20 seconds with hot water flowing. This clears the shared drain path and is the single most effective first step.
2. Clean the drain filter. Remove the bottom rack, twist out the filter, and scrub it under hot water. Reinstall and run a short rinse cycle to test.
3. Check the drain hose. Pull the dishwasher forward and look for kinks. Straighten any sharp bends.
4. Bail out the standing water. Use towels and a cup to remove the water so you can see the drain area clearly and prevent overflow when you pull the unit out.
$85 diagnostic applied to repair · OEM parts · Written estimate · 7 days a week throughout LA County.