Van Plumbing: How to Build a Complete Water System
Fresh water, hot water, drains, and grey water collection — here's how a van plumbing system comes together from tank to faucet.
A van plumbing system includes a fresh water tank (20-40 gallons), 12V water pump, PEX supply lines, sink, optional shower, water heater, and grey water collection. Materials cost $1,500-$5,000 depending on complexity. Most people use 3-5 gallons per day with water-conscious habits. Emery Custom Builds installs plumbing systems on every van we build, from simple sink setups to full hot-water shower systems with winterization capability.
Running water in a van isn't complicated, but it does require some planning. You're building a self-contained water system — fresh water storage, a pump to pressurize it, lines to move it around, fixtures to use it, and a way to collect and dispose of the drain water.
We install plumbing systems on every van we build at our San Diego shop, from simple single-sink setups to full systems with hot water, outdoor showers, and winterization capability. This guide covers the fundamentals we follow on every build.
How Do I Plan the Water System Layout for My Van?
Start by deciding what water fixtures you want and where they'll go. At minimum, most builds have a kitchen sink. Many add a shower — either an indoor wet bath, an outdoor shower, or both. Some builds include a second sink in the bathroom area.
Once you know fixture locations, map out the plumbing runs. The shorter the runs, the less pressure you lose and the fewer connections that could potentially leak. Keep the water pump close to the fresh tank — within a few feet is ideal.
Think about access too. Tanks need to be filled and drained. The pump and filter need to be serviceable. Connections should be reachable for tightening or repairs. Don't bury critical plumbing components behind permanent walls.
Where Should I Mount the Fresh Water Tank in My Van?
Most van builds carry 20–40 gallons of fresh water. Tank capacity depends on your usage habits and how often you can refill. Weekend campers can get by with 20 gallons. Full-time van lifers with a shower usually want 30–40 gallons.
Tank placement options:
- Under the van: Saves interior space but exposes the tank to road debris and freezing temps. Needs a skid plate or protective mounting.
- Inside, under a bench or bed: Protected from elements, easier to insulate for cold weather. Takes up interior volume.
- Rear of van, low and centered: Good weight distribution. Common in Sprinter builds with a rear garage area.
Use a food-grade polyethylene tank with a gravity fill port accessible from outside the van. A city water fill connection is a nice addition — it lets you hook up to a campground spigot without filling the tank.
Which Water Pump Should I Use in a Van Conversion?
The water pump pressurizes the system so water flows when you turn the faucet on. The Shurflo 4008 and Shurflo 4048 are workhorses in the van build world — reliable, quiet enough, and readily available. The 4048 is a variable-speed pump that runs quieter and provides more consistent pressure.
Mount the pump on a vibration-dampening pad or rubber isolators. Pumps vibrate, and in a van that vibration transfers to the floor and walls. A simple piece of dense foam or purpose-built isolator mounts make a big difference in noise.
Install an inline sediment filter between the tank outlet and the pump inlet. A simple 10-micron filter catches sediment and keeps it out of your pump and fixtures. Replace the filter cartridge every few months depending on water quality.
Should I Use PEX Tubing for Van Plumbing?
PEX tubing is the standard for van plumbing. It's flexible, durable, handles some freeze-thaw expansion (though you should still winterize), and connects easily with push-fit fittings like SharkBite or with crimp rings and a PEX tool.
Use 1/2" PEX for main supply lines and 3/8" for individual fixture connections. Color-code if you have hot and cold — red PEX for hot, blue for cold. It's not required, but it makes troubleshooting and future modifications much easier.
Secure PEX lines with clamps or hangers every 24–32 inches. Route lines away from heat sources (exhaust, diesel heater) and protect them where they pass through metal framing with grommets. Leave some slack at connections — PEX expands and contracts with temperature changes.
What Kind of Water Heater Should I Put in My Van?
If you want hot water at the sink or shower, you need a water heater. For van builds, the main options are:
- Tankless propane (Camplux, Truma AquaGo): Heats water on demand. No standby energy loss. Requires venting to the outside. Most popular choice for van builds.
- Small tank electric (Bosch Tronic, Ariston): 2.5–4 gallon mini tank heaters. Simple installation but draw significant power from the electrical system. Best for occasional use.
- Diesel-fired (Truma Combi): Heats water and air from the van's diesel tank. Premium option with dual functionality. Higher cost, more complex install.
For propane water heaters, follow the manufacturer's venting requirements carefully. Combustion gases need to exit the van, and the heater needs fresh air intake. Don't skip this — carbon monoxide is an invisible killer.
How Do I Install a Sink and Drains in a Van?
Kitchen sinks come in all sizes for van builds. Undermount bar sinks (10"–15" wide) are common. A folding faucet saves headroom when the countertop is close to overhead cabinets. We like single-handle faucets — they're easier to operate with wet or soapy hands.
Every drain needs a trap to prevent smells from coming back up the pipe. Standard P-traps work but take up space. HepvO waterless traps are compact, won't dry out, and work in any orientation — ideal for vans where space is tight and the vehicle moves.
Route drain lines with gravity in mind. Water runs downhill. If your grey water tank is below the sink, gravity drain works. If the tank is at the same level, you may need a slight slope or a sump pump arrangement.
How Do I Handle Grey Water in a Van Conversion?
Grey water is the used water from your sink and shower — it needs to be collected and disposed of responsibly. You have two main options:
- Fixed undermount tank: Bolts under the van and collects grey water automatically via gravity drain. Include a gate valve or ball valve for dumping at RV dump stations.
- Portable container: A 5–7 gallon jug that sits under the drain and you carry to a dump station or drain. Simpler to install but requires manual management.
Grey water capacity should roughly match your fresh water capacity. If you carry 30 gallons of fresh water, plan for at least 20–25 gallons of grey water storage. Some builders go 1:1 for simplicity.
How Do I Test and Winterize Van Plumbing?
Fill the fresh water tank and pressurize the system. Check every connection, fitting, and joint for leaks. Let the system sit under pressure for at least 30 minutes, then recheck. Even a tiny drip will become a problem in a van — there's nowhere for water to go except into your floor and walls.
If you'll be in freezing temperatures, plan for winterization. The easiest approach: install bypass valves around the water heater and pump, then blow out the lines with compressed air or pump non-toxic RV antifreeze through the system. PEX handles mild freezing better than rigid pipe, but it's not freeze-proof.
For four-season use, consider insulating water lines and the fresh water tank, and routing lines through the heated interior rather than under the van.
Should I DIY Van Plumbing or Hire a Professional?
Van plumbing is one of the more forgiving systems to DIY — a small leak is annoying but it's not going to burn your van down like an electrical mistake could. That said, if you're running propane for a water heater or want a clean, rattle-free installation that holds up on washboard roads, professional installation is worth considering.
We handle complete plumbing systems at our shop, from simple sink-only setups to full indoor/outdoor shower systems with hot water and winterization capability. If you want to talk through your water system plans, reach out — we're happy to help you think through the layout.
What Are Common Van Plumbing Questions?
How many gallons of water do I need in a van?
Most van builds carry 20–40 gallons. Weekend campers can manage with 15–20 gallons. Full-timers who shower in the van typically want 30–40 gallons. Most people use 3–5 gallons per day with water-conscious habits.
Should I use PEX or braided lines?
PEX is the standard for van plumbing. It's flexible, handles some freeze-thaw expansion, and connects easily with push-fit or crimp fittings. Braided stainless lines are great for short fixture connections. We typically use PEX for main runs and braided lines at the fixtures.
Do I need a water heater in my van?
If you want hot water at the tap, yes. Tankless propane heaters like the Camplux are the most popular option — they heat on demand and don't waste energy keeping water hot. You can also skip the water heater and heat water on the stove, but it's less convenient for daily use.
Related: All How-To Guides • Systems & Guides
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