Sacred Cow replied:

Lance,

You will need to tee the sullage hose of the washing machine into your caravan's sullage line. Do this tee as close as possible to the sullage outlet on the van and fit a non-return valve at the end of the existing sullage line before the new tee. Otherwise when the washing machine pumps out you will get its discharge coming out of the shower etc (if you have one). The non-return valve must be installed perfectly horizontally and should not be a spring loaded type as there is next to zero pressure to open it.

Also install a tap on the water line to the washing machine. The water line should have a pressure reduction valve fitted.

Sacred Cow