There are two general areas where you will commonly find water leaking from a dishwasher.
The first is from around the door; water will generally show up on the kitchen floor in front of the dishwasher.
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.
A third source of water "leakage" (though it really isn't a leak) is from the air gap.
The air gap is an anti-backflow device installed in the drain line, to prevent the dishwasher from accidentally siphoning fluid from your house's sewer line back into the dishwasher tub. If this air gap or the house's drain line becomes clogged, water can run out of the air vent, and generally it runs straight into your sink. Note, however, that this will only occur when the dishwasher is operating in the "pumpout" mode, trying to drain the tub. There is an illustration and discussion of the air gap in section 3-1.
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 as a drip, and not as suds on the floor.
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. See section 2-2, preventive maintenance.
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.
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 as described in section 3-1 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. (See figure 4-A) 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. See Chapter 5.
In models with plastic spray arms, the spray arm can split, causing similar symptoms.
Remove the kick plate as described in section 5-2 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. (See figure 4-B.) 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.
Pump seals get worn out. Just a fact of life. Rubber seal... metal shaft... you get the picture. Throw in some tiny bits of broken glass, plastic, nutshells, seeds, and other assorted abrasives over the years, and it's a wonder they last as long as they do. Bits of rust from your rusty dishracks can really accelerate the process.
Pump seal leaks will show up as water dripping from the motor or pump housing. (Or from the pump pulley in Maytag machines.) It may also get slung around a bit from a rotating pump shaft.
The solution is to rebuild the pump. In some designs, you pull the whole motor and pump unit and replace it with a new or rebuilt unit. See Chapter 5 for details.
On rare occasions, the leak will be coming from the sealing washers around tub heater mounts, dryer blower gaskets, or other small tub penetrations. You need to replace the gasket or seal. Drain or recirculation hoses have been known to get old and brittle and crack open. Replace the hose.
In sidewinder machines with butterfly drain valves, such as GE and Westinghouse dishwashers, (see section 1-2) you may get a leak from the drain valve stem. In most of these, this means pulling out the whole pump and motor unit and replacing it with a rebuilt unit as described in chapter 5.
Some Kitchenaid dishwashers have a solenoid drain valve which can also develop leaks. See section 4-3.