Fresh Water, Grey Water, Plumbing

Chapter 16: Skoolie & RV Plumbing Systems

Holding Tanks

For the fresh water tank location, we may have to get a little creative. There are two obvious installation points: Interior, and Exterior. Each has its own advantages and disadvantages, so we must consider carefully.

Exterior is relatively straight forward, mounting along the frame under the carriage is a great option that frees up interior storage space, but we will have to design, build, and mount some form of frame to hold the tank in place.

When mounting in the Interior, the best space we can think of, is under the bed. Unfortunately, that would mean giving up a large volume of interior storage space. On the other hand, mounting the tank in the interior means its less prone to freezing, unlike the under-carriage mount.

The Grey Water Tank can be mounted anywhere you have space, but should be mounted on the underside of the rig to allow your sink and shower to drain into the holding tank.

The Black Tank should be mounted on the underside of the Skoolie, directly below the toilet. Flushing the toilet is more of opening the trap door and allowing the contents to evacuate into the tank below.


It’s not just the holding tanks that you should think about insulating, but also the water lines. For house plumbing, it is advised to leave a faucet tap cracked, so that a steady drip can flow, preventing water lines from breaking due to expanding freezing water within the lines. While this may work if you are at a campsite with full hook ups; obviously, this is a terrible option if you are boondocking or have a limited water supply that you need to conserve.

There are other ways to prevent the holding tanks contents from freezing, such as agitating the water within, with an air pump.  Heat Tape and Round Foam Insulation can be used to help stabilize the temperature within the pipes.

Water Pump

The SHURflo 3.0 Revolution Water Pump looks like a solid pump. It’s 12v and uses 7amps, while that is a relatively high consumption, it’s not going to run anywhere close to a 24 hour draw; it may end up being 7amps daily. We will still need to account for the possibility of a higher amp draw in our battery bank calculations.

The SHURflo 3.0 uses 1/2” NPSM Male fittings; and uses an internal 55psi switch for “on-demand” pumping. If you turn on the shower, etc. and the water  pressure in the pipes drops below 25psi, the pump will start, the pump will maintain its output until the pipes pressure returns to 55psi, as in, when you turn off the shower. And of course they have some add-ons that we may be interested in.

Pipe Diameter

Fresh water lines will be a thinner diameter tube/pipe due to there being no need to pass solids through the lines. In theory, combined with a properly sized pump, this system should give us a nice water pressure in the shower and at the sinks.

Black water plumbing typically isn’t a huge challenge on a skoolie, most utilize a straight through gravity style toilet. A single large diameter PVC straight into the holding tank. The RV style toilet has a lid/flap that ”seals” the odor from entering the bathroom area. Additionally, a “breather tube” should be installed from the black tank to the high point on the exterior of the Skoolie. Like a “Porto-potty” this breather tube allows odors to escape the black tank, limiting the odors that reach the interior cabin.

Fresh Water Fill Line

We know that we will need a fresh water fill line, and a water pressure regulator, like this. When using the regulator, it’s important to connect it directly to the water source. If connected at the Skoolie/RV, your fill line could be over-pressurized, and thus damaged.

To find out more about how and where to fill your water tanks check out our blog post on Finding Free Fresh Water

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