A dishwasher that hums, runs its cycle and comes to the end with dry dishes and a dry tub is not failing to wash — it is failing to fill, and those are different faults with different fixes. Water reaches the tub through a short and very testable path: a stop valve under the sink, a supply line, an inlet screen, the inlet valve itself, and a float that tells the machine when to stop. There is also one commonly missed possibility, a flood switch that has tripped and is refusing to let the machine take any water at all.
Read this first
- Switch off the breaker and close the hot water stop valve before disconnecting any fitting or testing the inlet valve.
- Have a pan and towels ready — the supply line and the valve body hold water even after the stop is closed.
- Water in the base pan under the machine is not normal. If you find it, find where it came from before you put the machine back into service.
- Do not run a dishwasher that fills but will not stop filling. Close the stop valve and leave it closed until the valve is replaced.
Step by step
Confirm it is a fill fault and not a wash fault
Start a cycle and listen with the door closed for the first minute or two. A fill is an audible hiss or rush of water. If you hear nothing at all, you have a fill problem. If you hear water arriving but the dishes come out dirty, the machine is filling and the fault is in the wash action — spray arms, filter or circulation. You can confirm by opening the door a few minutes into a cycle and looking at the sump: it should be wet, with water standing in the filter well.
Check the stop valve under the sink
Dishwashers are fed from a small stop valve, usually on the hot supply under the kitchen sink. It gets closed during other plumbing work and forgotten, and it is worth checking before anything else because it is out of sight and costs nothing to rule out. Open the cabinet, trace the line to the machine, and confirm the handle is fully open. While you are there, run the kitchen tap and confirm you have hot water pressure at all — a machine fed by a supply that has been isolated at the main will behave identically.
Clean the inlet screen
There is a fine screen where the supply line meets the inlet valve, and it catches grit, pipe scale and rubber shed from an ageing hose. When it silts up the machine either fills slowly or not at all. Close the stop, put a pan underneath, disconnect the line at the valve, and look into the port. Pick the screen out carefully, rinse it, and refit it — do not leave it out, because the screen is what protects the valve. If you find heavy sediment, check whether recent work on the household plumbing stirred it up.
Lift and drop the float
The float is a small plastic cup or dome standing in the floor of the tub, and it rises with the water to tell the machine to stop filling. If it sticks in the raised position — held by a build-up of detergent residue, a piece of broken glass, or a label washed off a jar — the machine believes the tub is already full and will never take water. Lift it and let it drop several times. It should move freely with an audible click from the switch underneath. Clean the well beneath it while you are there.
Check whether a flood switch has tripped
Most machines have a shallow base pan under the tub with a float or a moisture sensor in it, designed to catch a leak. When it trips, the machine typically refuses to fill and may run its drain pump continuously — which reads as a machine that hums but never takes water. Tip the machine gently back or look under the toe kick with a flashlight and a mirror for water in that pan. If there is water there, sponge it out, reset the switch, and then find the leak, because it will trip again.
Test the inlet valve
The valve sits at the front base of the machine behind the toe kick, where the supply line lands. With the breaker off, unplug its connector and measure the solenoid coil with a multimeter — a coil that reads open is dead. You can also listen during a fill attempt: a distinct buzz with no water arriving usually means the solenoid is energised but the valve is silted up or the screen is blocked, while total silence points at the coil, the wiring, or the board not commanding a fill.
Check the door switch and read the code
A machine that does not believe its door is shut will not fill, because filling an open dishwasher is exactly what the interlock exists to prevent. Confirm the door latches firmly and the latch switch makes. Then put the machine into its diagnostic mode using the sequence in your model documentation and read any stored fault code. A code pointing at the fill circuit, the float, or a leak detection event will save you the rest of this list — guessing without it is how people end up fitting a valve that was never faulty.
What this repair costs
Doing it yourself
$5–$95
Hiring a technician
$150–$400
Prices are general estimates for typical US jobs, not quotes. What you actually pay depends on your appliance's brand and age, the part required, your region, and each shop's labour rate. The DIY figure assumes you supply the labour and buy the part yourself.
Parts you may end up buying
| Part | Install | Typical price | Typical lifespan |
|---|---|---|---|
| Spray Arm | easy | $15–$40 | 5–8 years |
| Inlet Valve | moderate | $15–$40 | 8–12 years |
| Drain Pump | moderate | $35–$120 | 8–12 years |
| Door Latch and Switch Assembly | easy | $20–$80 | 6–12 years |
| Heating Element | moderate | $25–$85 | 8–14 years |
| Float Switch | easy | $10–$35 | 10+ years |
| Door Gasket | easy | $20–$75 | 6–12 years |
| Rack Roller and Adjuster Kit | easy | $12–$50 | 5–10 years |
| Detergent Dispenser | moderate | $30–$100 | 8–12 years |
| Circulation Pump and Motor | advanced | $90–$330 | 8–14 years |
Still not fixed
When to call a pro
Call a plumber rather than an appliance technician if the stop valve is seized, the supply line is corroded at the fitting, or you have no hot water pressure at the sink — none of that is an appliance fault. Call a technician when the valve, float and door switch all test good, since a machine that will not command a fill is a control board diagnosis. If the flood switch has tripped, treat finding the leak as the real job; resetting the switch and carrying on just delays the water damage.
More dishwasher guides
- Dishwasher Not Cleaning — Find Out What It Is Short Of30–60 minutes
- Dishwasher Not Draining — Clear the Standing Water20–60 minutes
- Dishwasher Leaking — Find the Source Before It Damages the Floor30–90 minutes
- Dishwasher Not Drying Dishes — Why, and What Actually Helps15–45 minutes
- Dishwasher Soap Dispenser Not Opening — Why the Pod Is Still There20–60 minutes
- Dishwasher Spray Arm Not Spinning — Restore the Wash Action20–45 minutes
- Dishwasher Door Won't Latch or Stay Closed30–90 minutes
- Dishwasher Won't Start — Work Through the Lockouts First30–75 minutes
- Dishwasher Smells Bad — Clear the Sources in Order45–90 minutes plus a cleaning cycle
- White Film on Dishes — Hard Water Scale or Permanent Etching?30 minutes plus a test cycle
- Dishwasher Making Noise — Match the Sound to the Part30–75 minutes