I promise I will not attempt to fit anything myself, I'm useless! I have an uncle who's skilled enough! I am just trying to work out what I'm going to need to buy for him to fit. I want a shower and 1 sink fitting in my van. I think I'm going to have a tankless water heater that works on gas. I just can't work out how the waste water gets from the shower/sink to the waste water tank which I think will go on the floor of the van. Ok gravity is working for the sink but not the shower, or will I need a water pump to help it along? Can anybody find a diagram on how a plumbing system works on a motorhome?