Many people have an interest in saving the waste water from the washing machine.
One problem that doesn't seem to be realised in many cases, happens when long lengths of hose pipe are connected to the outlet of the washing machine drain hose.The idea being to use the grey water for irrigation on the garden.
This causes pressure on the pump in the machine and has caused much expense by having to pay for a technician to clear pump stoppages and replace prematurely 'failed' pump motors. You might call it over pressuring the drain pump. To water the garden with grey water from the washer, an intermediate reservoir would relieve the pressure on the wash pump. By pumping the wash water directly into a reservoir before the connection to the extension hose and then draining it to the garden by gravity or via a special pump would overcome the pressure on the washing machine. Think about the design of the washing machine. The maker never intended that the pump in the washer would be used for heavy duty purposes like pushing soap filled water through a long length of pipe.
Long lengths of drain hose can cause a syphon action, and drain water from the machine while it is washing. This causes the machine to refill repeatedly, and so waste water, not save it.
Some hardware stores sell long lengths of drain hose specially made for this purpose, therefore encouraging people to believe that it's ok to carry out this drainage modification to the machine. You might get away with it in some cases. It is prudent to suggest that you take advice about the method of grey water disposal. Ask Tony