Washing Machine Connections

• During the drain cycle, the water inside a dishwasher is pumped out by the pump mechanism and sent through the drain hose to the sink drain. The connection on the sink side could either be through the tailpiece, the long straight pipe located directly underneath the sink drain, or into the side of a garbage disposal. The drain hose is connected at either end by a hose clamp which is usually tightened with a screw.
  
  

Sink Drains

• The tailpiece underneath the sink is held in place by the sink flange in the bottom of the drain. In the case of a garbage disposal, a special mounting bracket is installed on the underside of the flange which holds it in place. Beneath the tailpiece or garbage disposal is a curved section of pipe known as the p-trap, which keeps sewer gases from coming through the drain.
  
  

Clogged P-Trap

• If the p-trap is clogged, it will prevent water from draining. When the dishwasher pumps out the dirty dishwater, it will have nowhere to go but up and into the new sink. There are a couple of ways to fix a clogged p-trap. Try inserting one end of a plumber's snake into the drain opening and continue until you feel it pass through the p-trap. Move the snake back and forth in the p-trap bend until you see the water level in the sink start to go down. The second way to break up a clog in the p-trap is to simply unscrew the couplings holding the p-trap in place, pull it out of the drain line, and power through the clog with a garden hose or bit of wire. Keep a bucket and towels handy when you pull the p-trap out of the drain.
  
  

Clogged Sewer Main

• All the drain pipes in a house drain to the municipal sewer system or septic tank through one large drain pipe called the sewer main. A clogged sewer main can not only cause a dish washing machine to drain water in a new sink, but will clog up every drain in the house. To clear out a sewer main, locate the clean out plug and remove it with a wrench or pair of pliers. Rent or purchase an electric auger from a local hardware or plumbing store. Run the auger through the sewer line towards the house until the drains begin flowing again.