A 40L Tank 300 water tank can be a practical size for touring, but the real question is not simply “How many days will it last?” Plan water around the number of travellers, trip length, temperature, cooking and washing, then keep a separate reserve. Also allow for roughly 40kg of water before the tank, pump, hoses and mounting hardware are added to the vehicle.
Quick answer
A fixed 40L setup suits travellers who value integrated storage and an optional shower, provided the tank is securely mounted and the filled weight fits the vehicle's payload plan. Do not assume the tank or every hose is suitable for drinking water: verify the specification of the complete system before using it as a potable supply.
Start with a trip-water calculation, not the tank size
There is no honest universal answer for how long 40 litres will last. Two people using water only for drinking and basic cooking will consume it very differently from a family using the same tank for dishes, dusty-trail cleanup and showers.
Use this planning sequence:
- Count every traveller, including children and any water needed for pets.
- Count travel days plus a delay margin for a closed road, puncture or changed campsite.
- Adjust for heat and activity. Healthdirect notes that fluid needs vary with temperature and physical activity, and that people should drink regularly in hot weather rather than waiting for thirst.
- Add cooking and washing separately. A shower can use the reserve far faster than expected.
- Protect an emergency reserve. Do not treat every litre in the main tank as normal campsite-use water.
As a general health reference, Healthdirect lists about 2.6 litres of daily fluids for men and 2.1 litres for women, while also explaining that needs rise in hot or humid conditions and during activity. Remote-area requirements can be higher, so check route-specific advice. The Northern Territory's camping guidance, for example, says at least two litres of drinking water per day and more when outdoors or exercising. These figures are starting points, not a promise that a 40L tank makes a particular trip safe.
Useful sources: Healthdirect — drinking water and your health and NT Government — camping safety.
What does 40L add to your Tank 300?
One litre of water has a mass of approximately one kilogram, so a full 40L tank carries about 40kg of water. The installed system weighs more once the tank body, pump, brackets, fittings, hose and wiring are included.
That matters because every accessory and item of luggage shares the vehicle's available payload. Add passengers, fuel, recovery equipment, a fridge, drawers, roof equipment and tow-ball load before deciding that 40L is “only” 40kg. Our Tank 300 roof-load calculation guide explains the same whole-vehicle principle for rooftop gear.
Before touring, confirm the vehicle's limits in its owner's information and compliance labelling, include the tank's filled mass in your load sheet, and use a weighbridge when the build is close to its limits. Keep heavy water low and securely restrained; avoid placing it where it blocks service access, interferes with seat hardware or becomes a projectile under hard braking.
Choose the package by the job you need it to do
The current 40L trunk water storage tank and shower kit for GWM Tank 300 is listed with separate package choices. Read the selected variant carefully rather than assuming every option includes the tank.
| Listed option | Best considered when | Confirm before ordering |
|---|---|---|
| 40L Wilderness Edition tank | You need integrated rear water storage | Mounting position, outlet access and intended water use |
| Electric shower expansion bag | Rinsing people, pets or equipment is a priority | Pump power, hose reach and water consumption |
| Rapid water-injection package | Faster, cleaner filling matters | Filler routing, cap access and venting |
| Complete tank, shower and filling kit | You want an integrated camping setup | Every component, electrical protection and exact vehicle fitment |
Eight fitment checks before installation
- Exact vehicle version: confirm model year, petrol or hybrid version, and any cargo-floor differences.
- Usable cargo space: check drawers, fridge slides, seat movement, tailgate table and recovery gear together—not one accessory at a time. See our Tank 300 trunk-storage checklist for layout planning.
- Secure mounting: use load-rated mounting points and hardware suited to the tank and filled mass. A loose 40kg load is dangerous.
- Filler and vent routing: the system should fill without air locks, kinks or water spilling into trim and electronics.
- Outlet access: place the tap and hose where they remain usable when the cargo area is packed.
- Pump wiring: confirm voltage, fuse protection, cable size, switching and a safe isolation method with a qualified installer.
- Leak testing: test the complete system while parked before relying on it away from home.
- Full-load verification: reassess vehicle and axle loads with the tank filled, passengers aboard and normal touring gear packed.
Drinking water and utility water are different decisions
A water tank can be useful for showers, dishes and equipment cleanup without automatically being a safe drinking-water system. Potable use depends on the tank material, hoses, sealants, pump, source water, cleaning method and how long water is stored.
If the supplier has not confirmed potable-water suitability for the complete setup, treat it as utility water and carry drinking water in a separately verified container. Label outlets clearly so nobody assumes the wrong supply is safe to drink.
A simple pre-departure checklist
- Confirm the selected product option includes every component you expect.
- Calculate drinking, cooking, washing and reserve water separately.
- Record the full system weight, not only the water volume.
- Inspect mounts, hoses, clamps, wiring, fuse and outlet.
- Fill and leak-test the tank before packing the cargo area.
- Keep drinking water separate unless complete potable suitability is confirmed.
- Recheck vehicle and axle loads in touring trim.
- Carry a backup container that remains accessible if the main pump fails.
Frequently asked questions
Is a 40L water tank enough for two people?
It can be suitable for a short trip, but duration depends on heat, activity, cooking, washing and the reserve you protect. Calculate actual use rather than dividing 40L by a generic daily figure.
Does 40L mean 40kg?
The water alone is approximately 40kg. Add the mass of the tank, pump, brackets, fittings, hoses and wiring when calculating vehicle payload.
Can I drink from a Tank 300 water tank?
Only if the complete system—not just the tank body—is confirmed suitable for potable water and is filled, maintained and cleaned accordingly. Otherwise, use it for utility water and carry a separate verified drinking supply.
Will this setup fit both petrol and hybrid Tank 300 models?
The listing covers Tank 300 petrol and hybrid applications, but exact model-year and cargo-layout compatibility should be confirmed before ordering. Existing drawers, electrical equipment and rear accessories can change the available space.
Should the water tank be full while driving?
Follow the tank manufacturer's guidance. Whatever the fill level, the tank must be securely restrained, the cap and outlets sealed, and the load included in the vehicle's weight calculation.
Build the system around your trip
A good Tank 300 water setup balances usable volume, safe mounting, payload and easy maintenance. Review the 40L tank and shower-kit options, then contact Decision Maker 4X4 with your model year, powertrain and current cargo layout if you need package guidance.
Image note: the campsite hero and explanatory diagrams are AI-generated editorial concepts. The product photograph is from the live product listing. Always verify exact product contents and fitment before ordering.
