Water Crossing Wisdom

Steve Cassano — 20 June 2019
Crossing water with a camper trailer can feel like jumping into the deep end, literally. Here are a few swimming lessons to keep you afloat.

You wouldn’t be a true 4WD adventurer if you didn’t like a challenge or two when out on the tracks. And if that challenge can look epic at the same time, we say, why not?

One of the most picturesque challenges of all is the water crossing, which you’ll inevitably face whether you hit the harder steep inclines or tour on the open roads.

There are many types of water crossings you may face. They range from as simple as crossing a shallow weir, to as difficult as precariously navigating a windshield-height river crossing, such as those commonly found in northern Queensland.

There are just as many names for water crossings as there are types: ‘river crossing’, ‘creek crossing’, ‘underbody wash’... the list goes on. But whatever the body of water and whatever you call it, you can’t escape the need for prior planning and correct technique. 

Crossing water can be considered a two-part task. First comes preparation and second comes the crossing itself.


From the factory, all vehicles have a maximum wading depth as advised by the vehicle’s manufacturer. This wading depth is a safe guide when negotiating water in a stock vehicle, that has no major modifications.  

However, for many trailblazing adventurers, this maximum depth doesn’t cut the mustard, as many outback or even local crossings are well above this index. There are, however, a few things you can do to minimise issues when confronting deep water.

Water can pose threats to both vehicle and passenger safety (when diving gung-ho into a crocodile infested hell-hole, that is), but the most common threat will always be to your beloved 4WD. Water could be sucked into the engine via the air box, which is normally fitted on the left or right side of a 4WD. 

First thing to check is where the air box draws the air from. The air intake could be found hidden under the wheel arch, under the hood or just behind the front grill. Being aware where the 4WD’s air intake is helps decide the best option to prevent water ingress. No matter what fuel type, be it petrol or diesel, it can take just a thimble of water to hydraulic the engine – because water doesn’t compress as fuel does and subsequently makes for a very bad scenario for your budget and remaining journey. 

Do as serious tourers do and splash out; give some serious thought to fitting a quality snorkel. A snorkel elevates the air intake well above the standard position, often as high as the top of the windscreen, providing uninterrupted airflow and preventing water ingress. 

It’s worth noting that some factory mounted snorkels are of a two-piece design, where there are joins that do not guarantee a 100 per cent seal. So best check the system in a factory fitted snorkel (or even aftermarket) and attend to any gaps using mastic or similar before diving into that next big puddle.  

Another curveball is that most air boxes have water drain holes, so make sure to block these once paired with a snorkel again with a little sensor-safe mastic. 

As a seasoned traveller I carry a water blind/bra. It’s a bit like speedos for a 4WD. A water blind is another level of protection, especially if no snorkel is fitted or if the water is particularly challenging or deep. These water blinds are placed to cover the front of a 4WD to minimise water getting under the hood. These days most modern 4WDs have electrical systems that are well insulated from moderate water splashing in and around your engine bay, but if you suspect your particular 4WD is prone to electrical issues from water, then a water blind is cheap insurance and takes little time to fit and little room to store.  

The water blind solution could be as simple as a $10 tarp held over with a few strong straps, or as thorough as a commercial example – such as my water blind of choice from MSA for under $150. MSA versions have adjustable straps that can accommodate all types and sizes of 4WDs, including those with bull bars. 

As part of my tool kit I also carry a can of WD40 water repellent and if I suspect that water may affect the electrical system, then a good dose of spray around electrical parts can help prevent water ruining my day. This is even more vital with older 4WDs, that still use distributors and leads, which hate even a little moisture.  

Interestingly, most door and tail-gate frame rubbers don’t provide a water-tight seal (especially in my Jeep with removable door). So a good trick is to spray WD40 around the frame rubbers. Whilst not foolproof, spraying these seals can help keep the interior a little drier.

The final suggestion in preparing your 4WD is in regard to air breathers. All 4WDs have breather outlets fitted which are connected to four major 4WD components; you’ll find these outlets attached to the top of the front and rear axles, gear box and the transfer case. After a long drive (especially protracted low-range), these sealed components will get hot – and the air and contained fluids expand and retract as the temperature fluctuates within. Breathers allow this to happen without loss of fluids. 

The worst thing is to hit deep cold water and have these components suck water as they cool rapidly, if they’re below the water line. Surprisingly, many stock 4WDs have no tubes or relatively short tubes attached to these breather outlets. Fitting longer breather tubes, which are extended higher into the engine bay or even into the body cavity, will prevent water mixing with vital fluids. 

You could opt for a set of commercial breather kits for around $100 or do what I did and use some 3/8” fuel line I had lying around for way less. It’s an easy DIY job that would take no more than an hour or so, but make sure they’re affixed securely and allow for suspension articulation.      


The first things you need to do is ask yourself: do I have to cross this water? Are the 4WD, trailer and driver capable of crossing safely? If the answer is no to any of these questions, then find an alternative route and continue with your adventure.

If you’ve decided to continue, then there are a few checks to be made even before you get those front tyres wet. The best piece of advice I can give if traversing unfamiliar water is to stop, make a cup of tea and plan. If possible, try to hunt for information from locals or better still others that have recently crossed.

Firstly, check the depth across your intended route while searching the best path, which may not always be the shortest way. This may not always be feasible due to crocodiles inhabiting some rivers. Check for hidden holes, obstacles or possible hazards that could halt progress or cause damage to your rig. Whilst checking for depths, if you’re having trouble standing against the flow, you can safely guess that a larger, flatter surface (like a 4WD or a lighter camper trailer) will open the risk of being swept down river, which could end up as a possible roll-over or complete submersion. Not good really!

Setting an intended course must include setting an achievable exit, especially if it’s a well-used track. Not all exits are directly opposite the entry point and may be dozens of metres away. Frequently used entries and exits are often rutted, wet and slippery. This is where a good recovery plan results in a good outcome in the event of trouble.

So the route is planned, your exit is set, the recovery equipment is ready and you’ve decided that the crossing is safe. For most challenging crossings I select low range and second gear in my automatic, and the same should be best for most manual transmission 4WDs. Note, choose second gear, not first, as you need to maintain sufficient smooth torque throughout any crossing. Never depress the clutch or change gears while crossing, as there is the risk of water ingress through the myriad of seals on components, thus possibly letting water in and rendering your 4WD undrivable.

As soon as you enter the water maintain a constant speed where an even bow wave is created in front of the 4WD, to reduce water invasion into the engine bay. Avoid touching the brakes or accelerating too hard. As is true for most really challenging circumstances, I advocate a speed around fast walking pace, and never more than 20kph. If you have rear diff locks, engage them to add to tractability.

Regardless, I always have my recovery equipment easily accessible. If I have doubts, gear like a snatch or extension strap will already be connected and ready to enable a quick recovery, should it be necessary. I don’t want to muck around trying to connect shackles and straps whilst half underwater. Time is of the essence and a proper, well thought-out recovery plan is cheap insurance for an enjoyable journey.

Once you’ve cleared the water line, wait at the edge of the exit and allow water to drain back into the main body of water. This helps to minimise any erosion and makes it less slippery for following traffic. Finally, especially after a deep crossing, perform a visual check around the 4WD and trailer, to ensure you’ve not collected any unwanted debris and all is right.

If you follow these hints, your next water crossing should not only be successful, but worth a photo or two!

Happy wheeling. 


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