The easiest way to run plumbing is to have all your appliances that require water, on the same wall. This would limit the amount of holes to be drilled through the studs and prevent needing to run a complex series of pipes. Unfortunately this isn’t always ideal for the interior design layout of a tiny house.
We stuck to one wall as much as possible; locating the shower, bathroom sink, and kitchen sink all on the same wall. Due to space constraints we still needed to wrap around the opposite side of the house to supply water to the washing machine. We centrally located the water inlet on the outside of the tiny house near the trailer hitch so that we could disguise it at a later point in time, and because that location made sense to supply water to both sides of the house.
I used spray paint to help me visualize where the plumbing would go so that I could plan out how to run the electrical. As one might assume, the red is for the hot water lines and the blue represents the cold.
We used PEX for the majority of the plumbing (All but one small segment in the shower that required some copper tubing). PEX uses plastic tubing with sharkbite fittings that drastically simplify the plumbing process. You just push the pipe into the sharkbite fitting and it locks it into place.
Once we had the system in place, it would hypothetically be air tight. So we pressurized the line using our air compressor, attached a pressure gauge and checked to see if the pressure reduced over time.
It did. We had a leak.
We re-pressurized the system and I traced the pipes listening for the escaping air. I thought I had it pinpointed so I used a technique I learned for checking for leaks in car tires; dish soap and water. For those not familiar with this technique, sprinkling a bit of water containing dish soap on a leak will cause bubbles to form. I located 3 spots where air was leaking. Mainly in a 4 way fitting where I had to screw in four SharkBite fittings. By wrenching them down further, the leaks went away.
After another pressure test we were good, but man that had been quite the test of morale. I’m not gonna lie, when we had a leak, I was pissed. I don’t highlight the things that went wrong with this build very often, but there were lots of them. At this point in the project, I was over it and just wanted it to be done with.
Before we sealed up the walls, we hooked up some water from my parents water supply hose to the inlet on the tiny house to do one more test. Water sprayed everywhere. Luckily it was on the exterior. There was a gap in the inlet valve that needed a better gasket to seat properly. After a little more finagling, it no longer leaked. Inside the house, everything was functioning fine.
We used a hole saw to drill through the subfloor for the drain piping and secured it under the trailer.
Finally we could insulate, and seal up the walls.
You can see a video of my build at https://www.youtube.com/watch?v=hYe1dT-fNQk