PLUMBING GUIDE 2008

Installing a washing machine or
dishwasher

Water supply for washing machines and
dishwashers

The supply of water to these is made via flexible hoses with isolating valves.
These enable the machine to be moved for maintenance work. Depending on
the machine, there may be cold supply only or both hot and cold.

If the machine is to be sited next to a sink or other existing plumbing
installation, the supplies and waste can be branched to this relatively easily.
Otherwise new pipe runs will need to be installed to the new location.

Connecting the water

Switch off the water and drain down the pipes to which you intend making
your connection. If you are branching from an existing pipe, cut the pipe and
fit a "T" shape fitting. This will mean making two cuts in the pipe to make room
for the fitting.

Connect the fitting (soldered or compression, depending on space and
preference).

Fit a length of pipe between the "T" and the position of the new machine.

Fit an isolating valve in this branch to allow for maintenance later. Several
makes of appliance connectors have integral isolating valves.

Fit a connector to the end of the pipe to which the rubber hose from the
machine will fit. Check the size and thread on this before buying.

PLUMBING GUIDE 2008

Plumbing the waste pipe

There are several options for the waste disposal from such machines. Check
the manufacturer’s details for recommendations. The most common is for the
flexible waste outlet to be fed into a standpipe arrangement. The diameter of
the pipe should be 40 mm.

Run a waste pipe through the external wall to discharge to the drainage
system.

See waste for new appliances.

This should have sufficient fall (dropping

downhill) for the volume of water. This is normally recommended as 6mm per
300mm length.

Fit a deep trap to the inside end at floor level adjacent to the machine. Cut
and fit a standpipe to the top of the trap. The usual length for this is 600mm
from the base of the trap. Secure this, and any other pipework, with clips.

Insert the flexible waste into the standpipe by the recommended amount.

Switch on the water supply and test the plumbing.

Self boring water pipe connections

An alternative for connecting the supply pipes is to use self-boring fittings.
Check with your water supply company first as not all suppliers approve of
their use.

Mount the fitting over the pipe and fix to the wall. Follow the instructions
carefully regarding the assembly and alignment of components. Ensure that
the valve is in the off position then insert it and screw home. Tighten the lock
nut then connect the flexible hoses for the machine. Switch on the valve and
check for leaks.