A Guide to Water Tanks

Glenn Marshall — 25 March 2021
Installing a purpose-designed tank in your 4WD is a bonus when it comes to carrying this valuable resource

Gone are the days when the only way you could carry extra water when you went camping was in a plastic jerry can. Not only did the water taste worse than drinking out of the garden hose, but the plastic would degrade over time, making them liable to crack, spilling that precious resource all through the back of your 4WD. These days there is a purpose-designed water tank to fit almost any free space you have and by adding a 12V pump, a breather and a hose with a tap on the end of it, you have a very practical solution. 


Yes, that’s what many people ask me. There are a few reasons actually, so let me explain. 

Firstly, having all your eggs in one basket means that if the basket breaks, you lose all your eggs. The same goes for carrying all your drinking water in only one container — if something happens, like a hose connection breaking or the water tank cracking, you will lose this valuable resource. 

I can attest to this, back in 2006 I was towing my camper along the Anne Beadell Highway with my 9-year-old son and upon reaching Vokes Hill Corner, I realised that at some stage one of the hose connections had snapped off at the tank and it had emptied as I bounced along the corrugated track. Still 400km from Coober Pedy, I decided to head south to Cook and then Nullarbor Roadhouse. 

I could see on the map that there were water points dotted along the track that could be utilised if needed. The first one was a big tank covered by a large roof that collected fresh water whenever it happened to rain. I had an empty 20L jerry can that I was able to fill and at the same time relieving some of the stress. We made it to Nullarbor Roadhouse safely and the decision was made to never face that situation again. 

Secondly, when adventures include long distance touring or remote travel, you need to carry additional drinking water. This is the main reason why I installed a water tank in the Prado because most of my travel is remote or covers long distances. Being able to carry 40L of drinking water in the 4WD means I have twenty days’ worth of life-sustaining liquid on top of what I carry in the camper. Because the camper water tank is susceptible to damage, having the water tank inside my 4WD is a great insurance policy. 

Finally, there are weight benefits too. It’s sometimes necessary to share the load and, in doing, so keep the tow vehicle under GVM and the camper under AGM. Carrying a 20L water tank in the 4WD doesn’t add a lot of weight but provides great back up. 


The good old PVC pipe picked up from your local hardware store is the cheapest and the easiest DIY project you’ll ever do, and you can make them fit anywhere. All you need is a length of pipe, elbows if bends are needed, end caps, pipe glue, and a couple of fittings. The biggest problems are the lack of water they can carry and can become brittle if mounted externally — PVC has a low UV stabilisation value. 

Water bladders are made from food grade PVC and are perfect if you only need to carry extra water every so often, as they even roll up making them easy to store. Generally, they are designed to sit behind the passenger seats or in the tub of your ute, but you can get smaller ones that sit in the passenger footwells. If this is an option you’re keen on, ensure they are constructed using food-grade materials and internal baffles are fitted that stops the water from sloshing around. It’s also a good idea to give them a good flush out with some bicarb and vinegar or water purifier before you use them as the water tends to have a strong plastic taste. 

Poly tanks are made from UV-treated impact-modified and food grade polyethylene, ideally suited to the 4WD market because they are strong and lightweight and can be made in all shapes and sizes. There are restrictions though, as each tank uses a different mould to be created. They can be mounted internally and externally, but you’ll need to use a tie-down solution as they don’t come with mounting points. 

Water from poly tanks is also susceptible to having a ‘plastic’ taste that can be reduced by using food grade hoses to fill and drink from plus giving the tank a regular clean with a bit of bicarb soda and vinegar or water purifier before giving it a good flush out. Also, make sure your poly tank is BPA free and complies with the Australian Standard AS2700 that covers plastics used for safe drinking water.

Stainless steel tanks are the best option if you’re looking for something that doesn’t have issues with taste. They are also more likely to last a lifetime if constructed properly — always check the welds and internal baffles are a bonus as they add strength. Also, make sure that Grade 304 stainless is used as it’s more resistant to corrosion and chlorinated water won’t damage it. 

While stainless tanks are heavier and more expensive than poly tanks or bladders, they can be customised to fit any space you have. They generally come with all the inlets and outlets tapped so connectors can be screwed in and some even have a 12V pump attached. 


There is a never-ending debate about this, but it depends on how much light can get into your system. If no light can penetrate your hoses or tanks, you can fill your tanks when not in use. The downside is the extra weight you’re carrying around for no reason, so you may as well empty your tank and let the hoses and tank air dry to prevent bacteria or mould from growing. I always give my tank a good flush with BioMagic WaterPure Tank Sanitiser then add some BioMagic WaterPure Water Purifier, picked up from snowys.com for a good price, before a trip.


I wanted a solution that would enable me to remove the water tank if I didn’t need it. I purchased a Boab 40L poly footwell water tank and breather hose kit before visiting my local irrigation specialist to buy some brass connectors to fit the ½in BSPT brass outlet and an on/off valve, some drinking water hose, hose connector, tap, and hose clamps. I already had a 12V water pump that I bolted to the side of my rear drawer system and connected to power via a switch.

Installing the breather hose was the biggest challenge as I needed to drill the right sized hole and then tap it to allow the plastic fitting to screw in with some silicon included stopping any water from leaking. This hose allows the tank to expand in hot conditions and makes it easier to pump water from the tank. 

I also needed to buy a couple of adapters because the inlet and outlet of the water pump were smaller than the food grade hose. Initially I tried to add some clear hose as a sleeve to make it all fit, but the water pressure would cause it to pop off. The adapters ensured the in and out connections were perfect. 

Using some plumbers tape, the brass elbow joint was screwed into the tank outlet before the valve was then added. The hose was then connected to the valve with a clamp and run-up to the pump where it was connected using a clamp. I then cut the hose at a position where it was higher than the tank and added the hose connector allowing me to disconnect the tank and remove it whenever necessary.

The final task was drilling a hole for the tap to fit into, connected it to the pump outlet and then gave it a test. In the past 18 months, it hasn’t leaked and provides great tasting drinking water and the perfect backup to my camper trailer water. 


Regulars How to Nuts and Bolts Water tanks 4WD