Dishwashers have become a permanent fixture in many homes across the USA in the last few decades. There are many
styles and manufacturer's to choose from, but almost all of them have the same requirements. Unfortunately, there have
been many different ways of connecting the same type of dishwasher over the years.
Most dishwashers require a 115volt electrical connection, these days with their own dedicated circuit. The drain is
typically connected to the tailpiece of the kitchen sink or a garbage disposal. The water supply is generally taken
from the hot water pipe of the kitchen sink.
The electrical connection is fairly straighforward. See the installation instructions for details, but the white wire(neutral)
gets connected to the white wire of the dishwasher, and same for the hot wire(black). The unit must also be grounded. Unqualified people should call a
The drain of a dishwasher is also very common. There are 2 different sizes of drain attachments, but the dishwasher itself
has a double size rubber end on it which will accomodate both drain sizes. There is a specific tailpiece for the kitchen sink
which allows the connection of a dishwasher.
A garbage disposal also has a built-in connection for a dishwasher, as the the disposal is designed to take up the space
of the tailpiece. Over the years, there have been many other ways of connecting the drain of a dishwasher to the main line.
Most variations should still be able to be connected during replacement.
An important difference that took place just recently on some newer models of dishwashers is the water
connection. Dishwashers used to use a specific fitting as standard. The older fitting was a 3/8" mip x 3/8" OD compression angle fitting.
This allowed the use of a flexible supply line to be used. For information on flexible supply lines, click here.
The new fitting is still 3/8" OD compression, for the feed connection, but the actual dishwasher joint is now 3/4" female hose connection.
The reason for this is that the older fittings were very difficult to work with with the dishwasher mounted in place.
The new 3/4" female hose x 3/8" OD compression fitting uses a swivel style hose connection for the dishwasher itself.
The other portion of the water supply is where it gets connected to the domestic water itself. This should normally(but
not always) have a valve on it. While the fitting for the flexible supply is always 3/8" OD compression on the dishwasher
end, there were at least 2 popular sizes for the other end, under the kitchen cabinet.
The picture above is a bit odd for a dishwasher connection, but be certain that many worse connections have been invented!
This connection in particular, however, shows at least the possibility of the two main styles of connection. The first is
the actual connection being used. The flexible supply is 4ft long. The dishwasher side remains the same, at 3/8" OD compression.
This side is 1/2" faucet connection. This is like a faucet flex supply in reverse. It is not uncommon to see a ball valve
used and then a 1/2" male adapter to convert to the flex supply.
Another version of flex supply available is 3/8" OD compression x 3/8" OD compression. The same on both ends. This would
allow for the end shown above to be connected directly to the chrome stop valve, thus eliminating the use of extra fittings.
There are not many steadfast rules when it comes to dishwashers, but this last option, coupled with the new swivel fitting
appears to be the new(hopefully common) form of connection.