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Camper Van Plumbing and Diagram

By May 24, 2018 May 28th, 2018 Miles Van Camper, Van Build Series


Miles Van Camper has an extensive plumbing system with both hot and cold water supplying a galley/kitchen sink, a wet bath/shower and an outdoor shower fixture that is accessed off the back doors.

Note: there is a photo gallery of the plumbing system at the bottom of this post!

Download my detailed plumbing diagram (PDF).

Checkout all the parts I used on the build (outside of basic hardware store items).

How It Works

Miles Van Camper has a 30 gallon fresh water tank that is mounted on the floor adjacent to the driver side wheel well. Below the van, on the passenger side between the front and rear axles, is a 30 gallon grey water storage tank. The design of this tank is very long but “short” so it fits in this space without being too “low”. On Promaster vans, the rear axle effectively determines the ground clearance and my goal was to not have anything underneath the van hanging below this point. So, this grey tank and the propane tank on the driver side ended up being at approximately the same level as the rear axle.

On the driver side of the van there is a locking panel that has both a pressurized¬† city-water connection and a gravity-fed fresh water tube that is used to fill up the tank. When city water is connected (a hose from a campsite, etc.) the water lines inside the van are pressurized from that city water connection. Otherwise (most of the time), the water lines are pressurized with a pump which pulls water from the fresh tank (at the bottom) and pumps in into/builds pressure with accumulator tank that is installed just downstream from the pump. The accumulator tank ensures that the pressure is “even” to the various places it’s used (galley faucet, shower, etc.). Even though this particular water pump is advertised as not needing an accumulator, I found that I needed one so that the water flow/pressure was constant enough for the hot water heater to trigger consistently. More on that below.

There is a drain valve underneath of driver side of the van near the rear bumper that can be used to drain the fresh water tank when it’s not in use.

All the water lines are inside the van except for the few feet of drain lines underneath the van to assist in all-weather camping.

Hot Water!

I used a propane powered on-demand water heater that is designed for RVs. It is installed underneath the refrigerator just above the van floor and the combustion gases are vented to the outside of the van on the driver side. This unit works by “sensing” when a hot water is needed at a faucet/valve and heats the cold water up to the desired temperature (which can be adjusted) as it flows through the unit. There are a few advantages of this system compared to standard tank-based water heaters. First, you’re not using energy (propane gas in this case) to maintain a tank full of water at a specific temperature. Also, you never need to “wait” until the tank heats up/recovers after using hot water. Finally, you can use as much hot water as you need without the tank emptying. Often RV tank-based water heaters have small tanks and need a re-heating period between heavy use such as a shower. The disadvantage of these on-demand water heaters is that take a few seconds to activate and there there must be adequate flow of water through the heater because it won’t trigger/turn on if the flow is too low. For instance, if you only turn on the hot water at the galley faucet a small amount, there wouldn’t be enough flow to trigger the unit to turn on and begin heating the water. As I wrote above, I needed to use an accumulator tank downstream from my water pump to “even out” the flow/pressure of the water. Before I installed the accumulator, the water heater did not consistently turn on.

Drains & Grey Water

The galley sink uses a small, RV-style trap under the sink. Water exits the trap and runs down underneath the van to the grey tank in a flexible 3/4″ hose.

The shower drains into a special, 1-1/2″ Hepvo trap. This device provides the functionality of a standard “p-trap”, but takes up less space under the shower pan because it can be installed “horizontally”. It also prevents grey water from back flowing “up” into the shower. The trap is connected to the grey water tank using flexible 1-1/2″ PVC.

The grey tank is comes with only the 3″ outlet opening at the far side of the tank designed for emptying. So, I had to add two rubber “grommets”. One is for the “inlet” where the grey water from the sink and shower are connected to the tank and the other is for the vent line (which also uses 1-1/2″ PVC) and terminates about 18″ above the floor inside the van under the bed. It uses a “air admittance valve” at the top of this vent pipe to prevent any odors from escaping while allowing air to get out of the vent line. It’s important to have a vent for your grey water tank. As the tank fills up with water, the air that is being displaced needs somewhere to go. If you don’t use a vent, the drains won’t work well or will drain very slowly.

I can empty the grey water tank using the standard 3″ Valterra “gate valve”¬†that I installed on the outlet of the tank. It has the typical “hub” connection for draining using a standard 3″ flexible RV sewer hose. I store my sewer hose in this handy storage tube which is attached to my hitch-mounted cargo/bike carrier.

Download my detailed plumbing diagram (PDF).

Checkout all the parts I used on the build (outside of basic hardware store items).