Storing fuel and water safely on your vehicle is not the same as carrying shopping

Storing fuel and water safely on your vehicle means preventing weight shift, keeping fumes out of the cabin and avoiding contamination that could stop your engine or make water undrinkable. Get these right and you extend range without compromising handling or safety. The principles that follow cover weight distribution, secure mounting, material choice and the checks that keep stored liquids reliable over rough ground.

Weight distribution shapes how your vehicle handles

Every litre of fuel or water you add changes the centre of gravity. Fuel sits high when mounted on roof racks, raising the centre and making the vehicle more prone to body roll on camber or sharp turns. Water stored in the same place has the same effect. The principle is simple: keep heavy loads as low and as central as you can.

Mounting jerry cans on rear door carriers or swing-away racks places weight behind the rear axle, which reduces traction at the front and can make steering feel light on climbs or when braking. A better arrangement puts fuel and water between the axles or just ahead of the rear axle, close to the chassis rails. Side-mounted holders or undertray tanks achieve this without eating into cabin or load space.

When weight must go high, split the load: carry part of your fuel or water low and part high, rather than concentrating everything in one place. Balance left and right as well. Two jerry cans of equal capacity should sit symmetrically across the vehicle's centreline, not stacked on one side.

Check the gross vehicle weight rating before adding tanks

Your vehicle's gross vehicle weight rating sets the upper limit for the combined weight of the vehicle, passengers, gear and stored liquids. Water weighs one kilogram per litre; diesel weighs slightly less. A roof rack carrying four jerry cans of water at twenty litres each adds eighty kilograms before you count the weight of the rack and the cans themselves. Add passengers, recovery gear, camping kit and food, and you can exceed the rating without realising it.

Weigh the loaded vehicle at a weighbridge before a long trip. If the total exceeds the rating, reduce the load or upgrade suspension to handle the extra weight. Overloading compresses springs, reduces ground clearance and puts strain on brakes and wheel bearings.

Secure mounting prevents movement and spillage

A jerry can that shifts under braking or on corrugations will eventually work its fastening loose or crack its own seams. Mount every container so that it cannot move in any direction: forward, backward, left, right or up. Metal jerry can holders with a pin-and-cam lock or a ratchet strap across the top do this reliably. Bungee cords stretch under load and are not adequate for fuel or water.

1. Choose holders designed for the type of container you carry, with support across the base and a locking mechanism at the top.
2. Bolt holders to the chassis, body or a rack that is itself bolted securely; self-tapping screws into thin panels will pull out over time.
3. Check that lids face away from exhaust outlets and that containers do not touch hot surfaces such as the exhaust or the back of the engine bay.
4. After fitting, shake each container hard by hand to confirm it cannot lift, slide or tip.
5. Re-check fastenings after the first day of travel and then weekly; vibration works bolts loose.

If a container does crack or leak, remove it from the holder immediately. Fuel dripping onto a hot exhaust is a fire risk, and water leaking into the cabin encourages rust and damages upholstery.

Material and venting keep contents clean and safe

Metal jerry cans are more durable than plastic and resist puncture better on sharp edges or when knocked by branches. They are also heavier when empty and conduct heat, which can raise fuel temperature on long, hot crossings. Plastic cans are lighter and insulate better but crack more easily under impact or UV exposure. Choose military-specification metal cans for long expeditions where rough handling is certain, and food-grade plastic cans for water where weight savings matter.

Never use a container previously used for fuel to store drinking water. Residue remains in the plastic or metal even after rinsing, and it will taint water and make it unsafe. Mark water containers clearly and keep them separate from fuel cans in storage and on the vehicle.

Venting prevents pressure build-up and vacuum locks

Fuel expands as it heats and contracts as it cools. A sealed can in direct sun builds internal pressure that can force the cap open or split the seams. Most jerry cans have a small breather hole or a vented cap to let air in and out. Check the breather is clear before travel, and open the cap slightly at the end of each day to release pressure before it damages the container.

Water tanks and cans need venting too. Without it, pouring water creates a partial vacuum that slows flow and can collapse a flexible container. Fit a small vent tube to fixed tanks, positioned high enough that water cannot spill out during steep climbs or descents.

Fume management keeps the cabin breathable

Fuel vapour is heavier than air and sinks into footwells and storage areas. Even a well-sealed can releases some vapour over time, especially when warm. Never mount fuel inside the cabin or in an enclosed rear compartment without ventilation to the outside. Rear door-mounted carriers and roof racks keep fumes away from passengers; undertray tanks vent to the underside of the vehicle.

If you must carry fuel inside, use a vapour-proof container designed for cabin use and limit the amount to what you need for a day. Open windows or vents regularly to clear any accumulated vapour. Headaches and nausea are early signs of fuel vapour exposure; if they appear, stop and ventilate the vehicle immediately.

Water does not produce fumes, but it can grow algae or bacteria if stored in warm conditions for more than a few days. Keep water containers out of direct sun where possible, and treat stored water with purification tablets if it will sit for longer than a week.

Contamination prevention starts before you fill

Dirt, dust and water in fuel will block filters and damage injectors. Fill jerry cans from clean pumps where possible, and inspect the nozzle before inserting it. If the nozzle is caked in mud or the fuel station looks neglected, find another supplier. In remote areas where choice is limited, filter fuel as you pour it from the can into the vehicle's tank using a funnel with a fine mesh or a chamois cloth that traps water.

When filling water containers, rinse them first with a small amount of the water you are about to store, then discard the rinse. This clears dust and any residue from previous use. Avoid filling from stagnant sources such as ponds or slow-moving streams unless you have a filtration system that removes parasites and bacteria. Running water from a tap or a fast-flowing river is safer but should still be treated before drinking.

Cap containers tightly as soon as filling is complete. An open cap invites insects, dust and rain, all of which contaminate contents. Check caps before setting off each morning; a cap that worked loose overnight needs retightening.

Temperature extremes affect both fuel and water

Diesel gels in freezing conditions, and water freezes solid. If night temperatures drop below zero, bring water containers into the cabin or wrap them in insulation. Fuel cans can stay outside, but add a cold-weather additive to diesel if temperatures are expected to fall well below freezing. Petrol does not gel but can form condensation inside the can, which then mixes with the fuel and must be filtered out.

In hot conditions, fuel evaporates more quickly from poorly sealed containers and expands enough to overflow if cans are filled to the brim. Leave a small air gap at the top when filling in warm weather, and store cans in shade where possible. Water heats to the point where it is unpleasant to drink; insulated containers or a wet cloth draped over a jerry can and kept damp by evaporation will keep water cooler.

Fixed tanks and jerry cans serve different purposes

The table below compares the two main storage methods and the situations that favour each.

Jerry cans let you adjust capacity trip by trip and are easier to refill at stations where the vehicle cannot reach the pump. Fixed tanks extend range without cluttering the exterior but add complexity and cost. Many overland setups use both: a large auxiliary fuel tank for main range and one or two jerry cans for emergency reserve or to carry fuel to a stranded vehicle.

Inspection and maintenance prevent failures on the move

Check every container and its mounting before departure and then daily during travel. Look for cracks, splits, dents that could develop into leaks, and any sign of seepage around caps or seams. A small leak caught early can be patched or the container replaced; a leak discovered when half your fuel has drained onto the ground ends the trip.

Clean containers inside and out at the end of each journey. Fuel cans should be emptied, rinsed with fresh fuel if possible, and stored with caps slightly loose to allow any remaining vapour to escape. Water containers should be emptied, rinsed with clean water, and dried completely before storage to prevent mould and odours. Sunlight and heat accelerate plastic degradation, so store containers indoors or under cover when not in use.

Replace any container that shows signs of UV damage, stress cracking or permanent deformation. Metal cans that have rusted through at the seams or developed pin-holes are no longer safe. Plastic cans that have become brittle or discoloured have reached the end of their service life. A failure in a fuel container while travelling is both a safety risk and a logistical problem; replace worn containers before they fail.

Test your setup on a short trip before committing to a long one

Load your vehicle with the fuel and water you plan to carry on expedition, then drive a challenging local route with steep gradients, rough surfaces and tight turns. Pay attention to how the vehicle handles, whether any containers rattle or shift, and whether fumes reach the cabin. Adjust mounting, redistribute weight or change container positions until the setup feels stable and secure. What works on flat tarmac may not work on a rutted track, and finding that out close to home is better than discovering it several days into a remote journey.

For more on preparing for extended travel, read our guide on maintaining your vehicle on expedition. If weight and kit choices are still open, the article on what to pack for remote overland travel covers the balance between carrying enough and carrying too much.

This is an information site about overland travel and expeditions. It does not organise journeys or sell equipment.

#Water storage #Roof rack #Fuel consumption

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