The water is held in a 70L Fiamma tank.  The waste water drains into a container that can easily be emptied.  It is all powered by a 12v pressure operated pump (Don't skimp here, I bought a cheap one from China off Fleabay to begin with but realised that you get what you pay for and opted for a more expensive Jabsco pump with an in-line filter).  The water proved quite a headache for a while as I found the only place I could get the right fittings was through the internet.  I found it tricky knowing which fittings I needed without having them in front of me.  After a lot of trial and error I opted for a 12mm Push fit system.  We decided that even though we had left room to run the pipes to the shower we would keep things simple and use a separate 12v pump and a bucket for the shower.