There are two general areas where you will commonly find water leaking from a dishwasher.
The first is from around the door.
The second is from some component under the tub. The most common sources are pump seals and water valves, though it really can come from just about anything else under there, such as heater mounts, float switches, dryer fans, hoses, etc.
A slow, under-tub leak may go years without being detected. Often the tile or linoleum in front of the dishwasher is slightly raised, and water does not flow uphill. A slow leak beneath the tub can rot a wooden floor or cabinetry. It can also cause odors, mildew, etc. Often the first sign you might see is water leaking under the cabinetry and into the space beneath the kitchen sink.
It pays to pull off the kickplate every six months or so and look around under there with a flashlight for any sign of a drip. Do it while the machine is running. Also check the hot water shutoff valve beneath the sink for leaks, and exercise it; open and close it a couple of times and make sure it works so that you will be able to shut it off when you need to.
If you do not see any physical damage or excessive soap scum buildup on the door seals, it is rare for them to be the source of a leak.
If you think they are leaking, try cleaning them first. Really get in there and get all the built-up detergent and gunk out of there. Pay particular attention to the area around the inside bottom of the door; it tends to collect detergent build-up, food particles and soap scum. Use Lime-Away or full-strength white vinegar to remove any hard-water calcium buildup.
A particular Whirlpool machine was designed with a “bladder,” or expandable rubber chamber, at the top of the water tower. This bladder expands under water pressure to mate the tower with the upper spray arm. These bladders can develop holes. A jet of water may shoot out of the holes, and no matter how good the door seal is, the waterjet will blow right past it, causing an apparent “leak.” To replace the bladder, simply unscrew it from the top of the spray arms.
Vertical Maytag machines may exhibit this same symptom. The culprit is a sealing ring beneath the spray arm assembly; it wears out and allows a high-pressure jet to blow water past the door seal.
In models with plastic spray arms, the spray arm can split, causing similar symptoms.
Suds are great when you’re washing dishes in a sink. In your dishwasher, not so much.
Using the wrong detergent can cause sudsing during the wash cycle. When this happens, the suds may rise above the level of, or be splashed over the door sill. It usually shows up on the floor as a drip, and not as suds.
To diagnose, open the door during a wash cycle and look inside. A high level of suds will be obvious to you.
The solution is to change detergents. I highly recommend powdered Cascade™ detergent.
To get through the cycle you’ve already started without spilling too much more water, try adding a couple of tablespoons of cooking oil to the wash cycle. The oil will knock down the suds and it will be washed out during the rinse cycle.
To look for further floor leaks, you will need to look beneath the tub.
To do this, you will need to remove the kick plate underneath the door, and look under there with a flashlight.
Removing the dishwasher from under the countertop
And to repair the problem, you may possibly even need to remove the dishwasher from under the kitchen counter.
To remove the dishwasher from under the counter, first UNPLUG THE DISHWASHER or TURN OFF THE BREAKER.
Bail or sponge or vaccum as much water out of the dishwasher as possible.
You will need to reach under there with pliers or a screwdriver and disconnect the water feed tube.
Disconnect the drain from your house’s system. Usually this is easiest at your air gap or garbage disposer connection, or where the drain enters your house’s plumbing.
Remove the screws holding the dishwasher to the underside of the countertop.
If the dishwasher has adjustable feet, set them on the lowest setting possible, especially if there is a lip on the flooring in front of the dishwasher (perhaps there is raised tile, or linoleum or other flooring.) Make sure there is nothing sharp sticking out to gouge or scratch the flooring.
Slowly slide the dishwasher out from under the countertop, making sure your drain and fill hoses do not interfere with movement.
Re-installing the dishwasher
Re-installing the dishwasher is pretty much the opposite of removing it, with two things to watch out for.
1) When you readjust the legs, make sure you level the dishwasher. If anything, you want it sloping slightly towards the rear. Too much slope forwards can cause water to slosh over the front door sill. You will also need to raise it enough to reinstall the mounting screws into the countertop, but not so much that the countertop interferes with the door opening!
2) Make sure you plug the power cord back into the correct receptacle. Most dishwashers are plugged into a receptacle under the sink…into the same wall outlet as the garbage disposal. The garbage disposal receptacle has a wall switch…if you plug the dishwasher into the wrong receptacle, your dishwasher may not work unless the wall switch is on!
Water Solenoid Valve
Remove the kick plate and look at the water inlet solenoid valve.
On occasion, the guts of the water valve may rot out.
This usually shows up as a very slow drip coming from the top of the water valve solenoid. If the leak has been going on for a while, there may also be traces of rust or mineral deposits on top of the solenoid. The solution is to shut off the water supply and replace the valve.
On rare occasions, the diaphragm within a water valve has been known to rupture. When this occurs, water will start filling the tub and will not stop. The anti-flood float switch will not close the valve. All it does is shut off the valve electrically, and this is not an electrical problem. The water will continue flowing no matter how much runs out onto the kitchen floor. Better hope it doesn’t happen while you’re not home!
The solution is to shut off the water supply and replace the valve.