Planning the route of the waste pipe:
The key factors to consider when planning the route of the waste pipe are to keep the route as straight and short as you can and to avoid making it too steep.
The run should be made up of 32mm (1.25 in) diameter pipes, efficiently removing waste water to an outside drain. The waste pipe itself should not be more than 1.75m (5ft 9 in) in length. If you find that a longer run of pipe is required, it may be better to use piping of a wider diameter, perhaps a 38mm (1.5 in). If this option is chosen, the run must not be longer than 2.3m (7ft 6 in).
Also you may need to overcome the problem of connecting a 38mm pipe to a 32mm trap outlet, this is easily dealt with by fitting a reducer to the different sized pipes. The waste pipe must also slope enough for the water to run away at an efficient rate, the angle of the slope will depend largely on the diameter of the pipe being used and its overall length to the outside drain.
Putting in drainage:
It is easiest to hook the dishwasher or washing machine’s outlet hose over the rim of the kitchen sink when required. This however simple can prove to be inconvenient and not very attractive.
Alternatively, an open-ended stand-pipe can be fixed to the wall with the machine’s outlet hose permanently hooked onto it. If this is your chosen method for drainage, the best size for the open end of the stand-pipe is at least 35mm diameter, positioned at least 600mm (24 in) above the floor.
Also, a deep seal trap of approximately 75mm (3 in) should be fitted to the at the base of the contraption. To carry the waste water to an outside drain, a branch waste pipe should be installed leading from its outlet to an exterior gully.
If the drainage system is being installed on an upper floor of the household, then the branch waste pipe should lead out to the main soil and waste stack of a single stack system. In some situations it may be a viable option to fit the drainage from the machine by leading the waste pipe directly to the trap of the kitchen sink - though this is not generally advised by washing machine manufacturers as they warn of this system of drainage causing problems such as back-siphonage.
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