The basics of plumbing are very easy to learn.  I went out and bought a 1/2" PEX crimper, and ran all of my water lines at 1/2".  The water system starts at the water inlet, then flows into the tank.  I used a 102 US Gallon tank which tucked nicely underneath the stairs.  From there the line splits two ways.  The first to a 1.5" drain valve in case I wanted to drain the system.  The second went to the water system, which consisted of a SHURflo strainer, 120V pump, and accumulator.  

In my small house, water feeds the kitchen sink and the bathroom shower.  I use an Eccotemp tankless propane heater to supply the hot water. 

For waste, I opted for a Nature's Head Composting Toilet; it is manufactured in the US, and built very well.