Camper Van Water System Guide: Tank-to-Tap Design

A camper van water system must store, move, heat and dispose of water without contaminating it, overloading the vehicle or hiding leak points. Those requirements are connected. Selecting parts independently produces predictable failures: oversized tanks, noisy pumps, starved heaters and inaccessible fittings.

Define the water service before the hardware

An indoor shower is not just another fixture. It changes tank weight, hot-water recovery, moisture load, dump frequency and floor plan. Test a similar Class B rental and record water used per day before permanently giving a large part of the van to a wet bath.

Draw one complete schematic

A typical fixed system is:

potable fill → fresh tank → full-port shutoff → inlet strainer → 12V demand pump → optional accumulator → cold manifold → faucet and water-heater inlet → hot line → mixer → gray tank

Add a protected tank vent, drain valves, low-point drains, city-water interface if required, pump isolation and service access. Every branch needs a reason. Capped dead legs retain old water and make sanitation harder.

The CDC's 2025 Safe RV Water from Tank to Tap guidance says to fill from a safe drinking-water source, follow the RV maker's draining/disinfection procedure and replace filters on schedule. A taste-and-odor filter is not automatically a microbiological purifier.

Size and mount fresh and gray storage

Use the RV fresh-water tank sizing worksheet to calculate gallons from measured use, occupancy and time between potable fills. Avoid sizing from a social-media build list.

US water weighs about 8.34 lb per gallon. A 30-gallon tank therefore carries about 250 lb of water before tank, brackets, heater and gray-water contents. Put that load into the payload and axle plan in the van conversion planning guide. Confirm the real door-jamb ratings and weigh the finished vehicle by axle.

An interior tank is easier to keep inside the heated envelope and inspect. An underbody tank preserves cabinets but faces freezing, road debris and ground-clearance constraints. Insulation slows heat transfer; it does not warm an exposed tank. Coordinate winter travel with the van climate-control guides.

The gray tank can be smaller if legal dump opportunities are frequent, but it must cover the interval between them. Never assume gray water can be released on public land, pavement or a campsite; use authorized dump or facility instructions.

Choose pump pressure and flow as a system

Select the pump only after listing the maximum pressure and minimum flow needs of the heater, filters and fixtures. More gallons per minute can empty a compact tank rapidly and may push a heater outside its stable operating range.

Pentair's Shurflo 4008 installation manual calls for an inlet strainer, flexible hose at the pump, adequate wire and fuse protection, low restriction and an accessible, solid mounting surface. Those details are model-specific; follow the exact manual for your pump. The RV water-pump guide explains sizing and noise control.

Use a dedicated switch so the pump can be shut off while driving, away from the RV or diagnosing a leak. Install the strainer where its bowl can be removed over a towel or tray. Keep electrical connections protected from drips and size the circuit using the actual current, run length and pump instructions.

Use one compatible plumbing family

RV systems commonly use 1/2-inch PEX or compatible flexible potable-water tubing, but “1/2 inch” does not prove two parts fit. PEX-A, PEX-B, reinforced hose, swivel adapters and pump threads use different connection systems. Use components rated for potable water, temperature and maximum pressure, then follow the fitting maker's cut, insertion, crimp or clamp method.

Keep tube supported but allow controlled movement. Protect every hole through sheet metal or cabinetry. Avoid hidden joints above batteries, inverters or distribution panels. Use flexible sections at a vibrating pump when its manual specifies them; hard tubing directly on the pump can transmit noise and stress the housing.

The RV PEX and fittings guide covers manifolds, bend strategy and pressure testing.

Add hot water only after doing the energy math

A kettle may cover occasional dishes with almost no permanent plumbing. Regular showers can justify a tank heater, tankless propane unit or combined space/water appliance. Compare:

• incoming water temperature;
• desired outlet temperature and flow;
• propane or electrical input;
• minimum activation flow;
• pressure range;
• required exterior vent/cutout;
• relief, bypass and winterization procedure;
• service network and replacement access.

Suburban states that its gas appliances must be installed or serviced by a qualified technician. Follow that principle for any combustion appliance and the applicable codes. Do not install an unvented portable propane water heater inside a van. Use the RV water-heater comparison before choosing.

Protect water quality

Fill only from a source confirmed potable. Use a dedicated drinking-water hose and keep both ends capped, clean and separate from sewer equipment. Do not place the hose end on the ground or insert a contaminated nozzle into the tank.

Keep the tank opaque, cool and closed. The CDC recommends following the RV manufacturer for annual or post-storage draining, disinfecting and flushing. It also warns that many filters improve taste without removing germs. Use the filter's certified claims and replace it on schedule.

Design the system so you can:

• drain fresh storage completely;
• drain or bypass the exact water heater;
• reach every low point and exterior fixture;
• remove filter cartridges before storage;
• inspect the tank interior or condition;
• clean the pump strainer;
• pressure-test joints;
• sanitize and flush without dismantling cabinets.

Installation and commissioning sequence

1. Freeze fixture positions, gallons and payload allowance.
2. Confirm tank support, heater clearances and exterior openings.
3. Dry-fit tank, pump, heater, vents, drains and access panels.
4. Install supported plumbing before finished walls and cabinets.
5. Wire the pump with the manual's fuse, wire size and isolation.
6. Flush construction debris and fill from a known potable source.
7. Prime one fixture at a time and purge trapped air.
8. Run every fixture alone and in combinations the system must support.
9. Shut the pump off under pressure and inspect every joint for moisture.
10. Drive with partial and full tanks, then reinspect restraints and fittings.

Common design failures

• fresh tank has no usable cleaning access;
• fill can outrun the vent and spit water back;
• pump shutoff PSI exceeds a heater or filter rating;
• no strainer, fuse or pump shutoff exists;
• rigid plumbing transfers pump vibration into a cabinet wall;
• a relief or drain line can wet occupants or electrical equipment;
• gray storage has no vent or authorized dump plan;
• plumbing cannot drain for freezing weather;
• full water pushes payload or rear axle over its rating.

Commissioning means more than seeing water at the faucet. Measure actual daily gallons, listen for pump cycling after every fixture is closed, check hot-water stability, observe gray drain speed and inspect after the first rough-road trip. Those observations tell you whether the system works as designed.