Should you travel with your caravan water tanks full or empty?

Out of all the issues that caravanners argue over, the question of whether caravan water tanks should be full or empty while travelling is one I’ve never fully understood. As far as I’m concerned, if I need water at my next camping destination, I’ll fill my tanks. Otherwise, I’ll travel with them empty.

However, some people have very strong opinions on both sides of the fence. So, we’ve taken an in-depth look at the question of whether to keep caravan water tanks full or empty and discuss the pros and cons of each option.

Reasons for having the water tanks full

Stability in windy conditions

Having your water tanks full puts a lot of weight down low in the caravan, lowering the centre of gravity and, supposedly, increasing stability. This is particularly noticeable when driving in windy conditions. Some sections of the Bruce and Pacific highways (in the east) are prone to substantial crosswinds and are notorious for caravan rollovers. Whether or not these are all caused by the wind is debatable. However, having additional weight down low will make the caravan less susceptible to severe crosswinds.

Good quality water supply

Water quality varies across the country. Some places are blessed with great tasting and clean water straight out of the taps, whereas other places aren’t. The reasons for poor quality water are varied, but the usual suspects are bore water supply, old water pipes, and drought conditions. By travelling with your caravan water tanks full, you’ll always have a supply of good drinking water available.

It keeps your options open

If you’re the sort of traveller who doesn’t like to plan your trips too much, you may want to give yourself the option of stopping overnight at a free camp rather than keep driving on to the next caravan park. Free camping without water is no fun so travelling with your caravan water tank full means you can pull up for the night anywhere you like.

Travelling with the water tanks empty

Less weight means better fuel economy

There’s no escaping the fact that travelling with your caravan water tanks full means towing a greater weight than if they were empty. As such, your tow vehicle has more to pull and thus, the more fuel it will use. All tow vehicles are different, but I have noticed our Toyota LandCruiser 200 Series will use an additional one litre of fuel per 100km for every 100 litres of water we have on board. It doesn’t sound like a lot, but over time and distance, with a possible 270 litres of water on board, we certainly notice the difference at the fuel bowser.

Less wear and tear in the tow vehicle

The more weight the tow vehicle has to pull, the harder it has to work and that results in greater wear and tear. You may find you will need to make more frequent oil changes when towing a caravan, especially with the constant need to pull the extra weight of full water tanks. Transmissions also work harder with the additional weight, and they may require more frequent servicing as a result.

Less wear and tear on the caravan’s suspension

The vast majority of caravans have fairly basic leaf spring suspension. The constant movement in the springs develops friction between the leaves, which causes them to wear out over time. Adding to their workload by keeping your caravan water tanks full means these springs work harder and can wear out much quicker.

Less payload for other items

Most tandem-axle caravans will have a payload of anywhere between 400kg and 600kg. If you have two 90-litre water tanks and you fill them up every time you hit the road, there’s 180kg of payload gone, and you haven’t stored a single personal item inside the van as yet. The situation could be worse with single-axle caravans.

Instability issues

I often hear RVers say that their caravans are unstable when the water tanks are empty, and therefore, they always travel with the water tanks full. They will sometimes get this advice from the caravan manufacturer. A well-designed caravan should be stable regardless of how much water it is carrying.

If you find that your caravan is unstable with empty water tanks, regardless of the prevailing weather conditions, you probably need to look at how other items are stored in it to ensure you haven’t incorrectly distributed the load. Either that or your caravan has a serious design flaw and needs to be checked by a qualified caravan repairer.

Tips and tricks

Keep your caravan water tanks either full or empty while travelling

It’s possible a lot of people experience instability in their caravans because their water tanks are neither full nor empty. If your tanks are just a third full, the water will move about in the tanks from side to side, shifting the centre of gravity and making the caravan feel unstable. Most caravans will be fitted with quality water tanks that contain baffles. These will minimise the effect, although they can’t eliminate it.

Where possible, keep your tanks either completely full or empty. If you have to drive with partially full tanks, consider reducing speed to minimise the effect of the water moving in the tanks. It’s important to consider if you want your caravan water tanks full or empty before starting the trip.

Understand how your water tanks work 

It’s important to know how the water pumps draw water from your tanks. Some caravans have the individual tanks interconnected so water is drawn from each tank equally, some can isolate individual tanks, and some vans have separate tanks for drinking water. Understanding how all this works means you can track and control how much water is being drawn from each water tank and how the weight distribution changes as you use water.

Keep the weight as close to the axles as possible 

If you don’t need to fill up all your water tanks, it’s best to fill the tanks closest to the caravan’s axles. That way, you keep the weight over the load-bearing points on the caravan’s chassis. Avoid filling any water tanks placed at the rear of the van unless it is absolutely necessary and ensure the weight is counterbalanced with water in tanks situated forward of the axles.

Final word

Ultimately, the decision to travel with full or empty water tanks will depend on your individual requirements for any given circumstance. For me, I cannot see the need to drag all that extra weight if you don’t need to. I mostly travel with empty water tanks unless I know I will need the water for free camping. That said, I do carry some drinking water that I know is good just in case my next destination has poor-quality water or if the region is drought-affected.

The towns you visit might not be able to spare a hundred litres or so for every traveller that stops by wanting to fill up, often only to move on again the next morning. Bear this in mind, too, when considering whether to keep caravan water tanks full or empty.

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