Note: costs mentioned below are given in US dollars as a general point of reference — actual prices vary by country, currency, and local market.
Plan for roughly 1 gallon (4 liters) of water per person per day for drinking, cooking, and basic washing. Rigid poly tanks cost $80-$400 depending on capacity (5-30+ gallons) and mounting hardware, while soft bladder-style tanks cost $40-$150 and pack flatter when empty but are more prone to punctures.
At a glance
| Tank type | Typical capacity | Price band |
|---|---|---|
| Soft bladder/collapsible | 5 - 20 gallons | $40 - $150 |
| Rigid poly tank (bed/cargo mount) | 10 - 30 gallons | $100 - $350 |
| Rigid under-vehicle/chassis-mount tank | 15 - 40+ gallons | $250 - $600 (plus install) |
How much water to actually carry
A commonly used baseline is 1 gallon per person per day for drinking and cooking, with 2-3 gallons per person per day if you're also washing dishes, rinsing gear, or showering. A weekend trip for two people at the higher estimate is roughly 12-18 gallons total — worth weighing against tank weight, since water weighs about 8.3 lbs per gallon, meaning a 20-gallon tank adds around 165 lbs full.
Rigid tanks vs. soft bladders
Rigid poly tanks hold their shape, are easier to plumb with fittings for a pump or gravity spigot, and resist punctures better — but they take up fixed space even empty and are harder to fit into irregular cargo areas. Soft bladders collapse flat when empty, which is valuable for cargo space on the way to a fill-up point, but are more vulnerable to abrasion and puncture from sharp cargo or rough mounting surfaces.
- Rigid tanks: better for permanent installs (bed-mounted, chassis-mounted), easier to plumb, food-grade poly is the standard material to check for.
- Soft bladders: better for occasional use or supplementing a primary tank, pack away small, need a protective base to avoid punctures.
- Chassis or bed-mounted rigid tanks free up interior cargo space entirely but need professional-grade mounting given the weight involved.
Mounting weight in the right place
A full water tank is genuinely heavy — mount it low and centered when possible (chassis-mount or low in a truck bed) rather than high (roof-mounted), since high water weight raises the vehicle's center of gravity and measurably affects handling and rollover risk, more than most other cargo of similar weight.
Keeping water safe to drink
- Use food-grade tanks, hoses, and fittings only — non-food-grade plastic can leach compounds into stored water over time.
- Sanitize new tanks before first use with a diluted bleach solution per the tank manufacturer's instructions, then rinse thoroughly.
- Don't store water for extended periods without periodic draining/refilling and occasional sanitizing — stagnant water can develop bacterial growth even in sealed tanks.
Never assume tank water is drinking-safe indefinitely just because the tank was food-grade when new — treat or filter water that's been stored for more than a few days, especially in warm conditions.
Frequently asked questions
How much water should I carry for a 3-day overlanding trip?
Are rigid or bladder water tanks better for overlanding?
Where should I mount a water tank on my vehicle?
Is tank-stored water safe to drink after a few days?
Sources & further reading
Figures, prices and policy details were current at the last-updated date above. Automotive pricing, incentives and regulations change frequently — verify time-sensitive details with the linked primary sources. Read our editorial policy and fact-checking standards.
