Water Tank Setup for Overlanding: Sizing and Installation Tips

Quick answer

Size your tank around real daily use, not the biggest number that fits: most overlanders get by with roughly 2 to 5 gallons per person per day when cooking and rinsing are included. Mount the tank low and centered over or between the axles, protect every line from abrasion, and test the full system with water before your first trip. If you only need a rinse station, a compact mounted option such as the ROAM Shower Room can cover washing without a full plumbed system.

A water tank is one of those upgrades that either disappears into your build or becomes a constant annoyance. The difference is almost always planning: how much water you actually carry, where the weight sits, and how the lines are protected from vibration and road grit.

This guide walks through the setup in the order you should do it, from estimating demand to the first leak test. It applies whether you are adding a fixed tank to a van or truck bed or building a simpler rinse-and-wash setup around a rack-mounted enclosure.

Start with demand, not tank size

Before you buy anything, estimate how much water your trips actually consume. A practical starting point is 2 to 5 gallons per person per day for drinking, cooking, and basic rinsing, with the higher end applying to hot climates, dusty travel, or trips where you shower. Multiply by people and days between resupply points, then add a small reserve.

This number is the one that matters. A tank that is too small forces constant refills and rationing; one that is too large adds weight high on the vehicle and water you may never use. Write the number down before you shop so marketing sizes do not pull you toward capacity you do not need.

• Count drinking water separately if you prefer to keep it in portable containers rather than a plumbed tank.
• Plan resupply points into your route before you commit to a capacity.

Choose the mounting location before the tank

Weight placement changes how your vehicle handles, so decide location first. Low and central is the goal: over or between the axles, inside the footprint of the vehicle, and as close to the floor as practical. Roof-mounted water raises your center of gravity and makes every corner feel heavier, which is rarely worth it for a heavy tank.

Check clearance around the spot you choose. You need room for the fill point, the drain, the pump or outlet, and any hose routing. If the only space you have is under a rack or inside a case, that is a legitimate location too, as long as you can reach the fittings without unloading the whole vehicle.

• Measure twice with the tank's real dimensions, not the listed capacity.
• Leave access to the drain and fill ports; you will use them every trip.

Pick the tank type and fittings

Tanks generally come as rigid tanks, bladder-style tanks, or portable containers, and each has tradeoffs. Rigid tanks hold their shape and can be baffled, but they take permanent space. Bladders fit odd cavities but can shift and are harder to clean. Portable jugs are simple and removable but need to be secured so they do not become projectiles.

Fittings matter as much as the tank. Use a fill port you can reach with a hose or jerry can, a drain at the lowest point, and a vent so the tank does not glug or pressurize. Match thread types and use a sealant rated for potable water on any threaded connection that carries drinking water.

• Confirm whether the tank is rated for potable water before you use it for drinking.
• Keep spare washers and a thread sealant in your spares kit.

Mount the tank so it cannot move

A tank that shifts is a tank that will eventually crack a fitting or wear through a hose. Use brackets or straps rated for the loaded weight, and spread the load across the tank body rather than pulling on one point. Add padding or a rubber interface between the tank and any hard surface to absorb vibration.

If you are mounting to a rack or crossbars that lack channels for sliding hardware, you may need a different attachment approach. The ROAM Rugged Mount Sandwich Plate Hardware kit exists for exactly this case: it lets you clamp around bars or a rack when there is no channel to slide a bolt into, using four plates and eight bolts with washers and nuts.

• Torque fasteners, then re-check them after the first trip and after the first full tank.
• Never hang a heavy tank from a single strap or a single bolt.

Route and protect the lines

Run hose or tubing along paths that are already protected, and keep it away from exhaust, moving suspension parts, and sharp edges. Every place the line touches metal is a wear point, so add loom, grommets, or clips. Give the line a little slack for vibration and temperature changes, but not so much that it can snag.

Label your fill, vent, and outlet lines if more than one runs through the same area. Future you, troubleshooting a drip at camp, will be grateful. If you use a pump, mount it where it is accessible and where its wiring is fused and protected.

• Zip-tie or clip lines at regular intervals so they cannot rub against each other.
• Keep electrical connections above the highest expected water level.

Test the system before your first trip

Fill the tank and let it sit. Check every fitting, then drive a short distance on rough roads and check again. Small seeps often only appear once the vehicle is moving and the tank is sloshing. Fix drips now, not at camp.

Run the full sequence you will use on the road: fill, pressurize or pump, draw water, and drain. Confirm the vent works so the tank does not pull a vacuum or build pressure. If you are adding a rinse or shower setup, test that too, including how the enclosure attaches and where water drains away from your site.

• Carry a small towel and a spare fitting on the first trip as insurance.
• Drain and dry the tank between long storage periods to keep water fresh.

Your water tank setup, step by step

1. Estimate daily demand: Calculate 2 to 5 gallons per person per day for drinking, cooking, and rinsing, then multiply by people and days between resupply. Checkpoint: write the number down before you shop so capacity does not get decided by marketing.
2. Choose the location: Pick a low, central spot over or between the axles, and confirm you can reach the fill, drain, and outlet fittings without unloading the vehicle. Checkpoint: if the only spot is high on a roof, reconsider the tank size or type.
3. Select tank and fittings: Decide between rigid, bladder, or portable, then confirm potable-water rating, a reachable fill port, a low drain, and a working vent. Checkpoint: match thread types and use potable-rated sealant on drinking-water connections.
4. Mount it so it cannot move: Use brackets or straps rated for the loaded weight, spread the load across the tank body, and pad contact points against vibration. Checkpoint: if your rack has no bolt channel, use clamp-style hardware such as the ROAM Rugged Mount Sandwich Plate Hardware.
5. Route and protect the lines: Keep hose away from exhaust, suspension, and sharp edges, add loom or grommets at wear points, and leave a little slack for vibration. Checkpoint: clip lines at intervals so they cannot rub together or snag.
6. Test before the trip: Fill, let it sit, drive on rough roads, and check every fitting again. Run the full fill, draw, and drain sequence. Checkpoint: fix any seep before you leave, and carry one spare fitting.

ROAM gear that fits a water setup

• Shower Room: The ROAM Shower Room is designed for bathing outdoors and uses sturdy yet lightweight materials that attach to most vehicle rack systems. If your water plan is a rinse or shower station rather than a plumbed tank, this gives you a private, rack-mounted place to use it without permanently modifying the vehicle interior.
• Rugged Mount Sandwich Plate Hardware: This kit comes with 4 plates and 8 bolts, washers, and nuts, and is intended for mounting Rugged Mounts to roof racks or crossbars that lack channels for sliding carriage bolts. Tanks and water accessories often need to mount to bars rather than channels; this hardware is the specific fix when your rack does not accept a slide-in bolt.
• Starlink Mini Rugged Case Mounts: The Starlink Mini Rugged Case Mounting Kit mounts a Starlink Mini to the inside of a 66L, 83L, 95L, or 128L Rugged Case lid, keeping it protected and out of sight. Illustrates the same principle you should apply to water gear: keep sensitive equipment secured inside a protected case rather than exposed to the elements.

A water tank setup works when it matches your real consumption and stays put over rough roads. Size it from daily demand, mount it low and secure, protect every line, and test the whole system with water before your first trip. Do that, and water becomes one less thing to think about at camp.