Caravan Water System


How Does the Water System Work in Caravans? A Detailed Guide

Have you ever wondered how your caravan water system works? We’ve come a long way from the old days when caravans were simpler beasts.

These days, water tanks are divided into three different types: freshwater, grey water, and black water. To ensure that everything runs smoothly in your van, it’s a good idea to understand your setup.

Freshwater Tanks

When you’re travelling across Australia it makes sense to have your own supply of fresh drinking water. Not only that, but having fresh water also allows you to wash your hands, flush your toilet and even wash your clothes!

Most caravan fresh water tanks hold between 25 to 85 litres. A 100 litre tank holds enough water for two people for about two weeks (without showering, of course).

Freshwater tanks are made from a variety of different materials. Check out the different options that are available.

Caravan in field of flowers

Types of Fresh Water Tanks


A light and safe material, this is probably the most common material used to make freshwater tanks. They come in different sizes and are designed to prevent contamination. These are suitable for all types of vans and they are typically quite portable.

Galvanised steel

This type of tank is excellent for those who regularly go off grid. They’re the most durable and are resistant to corrosion. They also tend to be bigger so they can hold more water.

However, the disadvantage of this is that they’re heavier and don’t suit smaller, lighter caravans. They are usually found in bigger campervans and RVs.

PVC/Nylon Tanks

These are the lightest and smallest tanks available on the market. If you own a smaller caravan and plan on staying at campsites with a freshwater source, then they may be the best option for you.

Fresh water tank

A plastic fresh water tank

Where Are They Located in the Caravan/RV?

Depending on the model of the caravan, fixed water tanks may be installed in different parts of the van. Commonly they are under the floor but can also be inserted under the sink or the bench.

These tanks are filled via an inlet on the side of the van. For motorhomes this is fine, but for caravans it can be difficult to park them so that the inlet is adjacent to the water source.

Portable water tanks are connected to the side of the caravan through a pump and hose connection kit. If you use these, we recommend keeping a bag for them so that they don’t make a mess of your van when you’re travelling with them.

Can You Connect Mains Water to Your Tanks?

Many people fill their water tanks and go. But if you’re on-site, you can connect your tank to a mains water supply.

However, be sure to never connect the mains water supply directly to your van without an onboard tank unless you want to turn your van into a swimming pool!

With a tank in between, any issues with the connection between the mains and your van will result in mains water overflowing outside your van, rather than inside it!

Water Pumps

Water pumps draw water from your freshwater tank and distribute it throughout your van. There are two main types of electric water pumps: submersible and pressure.

Both of these pumps require a switch for activation. These can be pressure-sensitive switches or microswitches inside the actual taps.

These pumps typically run off 12V, so keep them in mind when sizing your battery and solar system.

Submersible pumps

Typically found in caravans, these are lightweight and inexpensive. They are better for portable water tanks and containers rather than fixed water tanks.

They always need to be operated with a decent level of water above them.

If they are run while dry, they can be damaged. While fixing them is cheaper than repairing a pressure pump, it is still a hassle and the last thing you need while out on a trip.

You don’t want your holiday to be ruined because you can’t take a shower!

Pressure pumps

These are mostly used in campervans and are more expensive. They operate via a diaphragm within the pump itself that pushes the water through the van’s piping and faucets.

They keep the water pipes on the outlet side of the pump under pressure at all times, which means that you will have water coming out the moment that you open the tap.

Water pump

A pressure pump

Pressure pumps are preferable for showers because of their superior water flow. However, they are more expensive to buy and repair.

Some people might find that they are also too loud, as they make quite a loud vibrating noise while in operation. This can be a problem at night, as your piping may slowly lose pressure over time, causing the pump to automatically turn on and re-pressure the system multiple times each night.

What Flow Do You Need?

The number of taps/outlets that you have in your van will determine the required flow of your pressure pump. Most caravans and campers have two to four outlets. Typically, these include the kitchen and bathroom sinks, the shower and finally, the toilet.

For three outlets, a 12V pump delivering 12 litres per minute will suit your needs. At this flow rate, the children can wash the dishes while you enjoy a shower! For four outlets, it’s best to have a 12V system with a capacity of around 17 litres per minute.

Don't forget to size your caravan water filter appropriately for the pump. If the filter can't handle the pressure/flow produced by the pump, it will be the bottleneck in the system and may even rupture, rendering it useless!

How Do Intake Strainers Work?

Intake strainers prevent debris and unwanted particles from entering your water pump. This ensures that the pump doesn't get clogged or damaged. Basic strainers use a metal screen to prevent grit from entering the water supply.

Water Pipes and Fittings

We shouldn’t need to say it, but don’t use your garden hose to fill your water tank. You need to use a food quality pipe specifically designed for this purpose. Otherwise, you are putting you and your family at risk of ingesting all kinds of nasty chemicals and bacteria.

12mm caravan pipes are the most popular choice and can be used with hot and cold water under pressure. Use push-on fittings to connect your water pipe to your tank and mains supply. Screw on fittings are also commonly found in caravans and their threaded appliances.

Caravan Tap

Water Heaters

There are several kinds of water heaters that run on a variety of different fuel sources, including electric, gas, and diesel.

Gas Boilers

These are regular water heaters that use an LPG cylinder to heat water. They heat water very quickly.

The advantage is that apart from requiring an LPG cylinder they’re not reliant upon any other outside source. As long as you can store the bottle securely, they’re very travel-friendly and suitable for off grid use.

However, condensation from combustion can be an issue so they need to be used externally with good ventilation. They also require servicing by a gas engineer which is an additional cost.

Caravan LPG

Electric Heaters

An excellent option if you have the means to use them. Electric heaters work as long as you have access to a mains outlet (like at a powered site) or solar panels with a decently sized battery.

They’re extremely efficient and very quick to provide hot water. They can also be more environmentally friendly if you are using solar panels.

Of course, the obvious disadvantage is that you need to have electric power to be able to use one. This makes them difficult to use if you plan on going off the grid.

Gas and Electric Heater

Why settle for one when you can have both? This hybrid style of water heater combines the best of both worlds.

It is flexible and allows you to use whichever power source is most convenient for you. Electricity when you’re at a powered site, gas when you’re unpowered. No need for any solar panels.

Of course, all of this comes with a price and this style of heater is the most expensive.

Diesel Heaters

Diesel dual air/water heaters are popular in campervans because they combine water heating with air heating in an efficient manner. A major advantage of these are that they don’t require checks or certification from an engineer.

The price of diesel also tends to be quite stable no matter where you are in Australia, whereas LPG can fluctuate significantly, especially in rural areas.

In recent years, diesel heaters have become very popular.

Caravan water heater

A diesel water and air heater

What size water heater is necessary?

Caravan water heaters come in a wide range of sizes. They are usually somewhere between 5 and 28 litres. The best size really depends on your personal use.

More people taking longer showers will require a larger heater. Remember that this will also consume more energy (whether that’s gas, electricity or diesel).

Whichever system you go for, buy from a reputable brand and, for your safety, make sure a licensed professional installs it.

Wastewater Tanks

Typically there are two main types of wastewater: grey water and black water.

Grey water comes from your sink and shower while black water is from your toilet. Both of these need to be disposed of correctly. As tempting as it might be, you can’t just dump your waste wherever you please.

Wastewater can impact local waterways (depleting them of oxygen) which in turn harms marine life living in that waterway and any other wildlife dependent on that water source.

Do the right thing when it comes to caravan and RV wastewater.

Also, don't forget to add chemicals to your caravan toilet and wastewater tank to keep them clean and odour-free!

Grey Water Tanks

Grey water tanks have virtually become a necessity in recent times. Many Australian National Parks require visitors to have a grey water tank installed, and to dispose of this water outside the park boundary. For this reason, you need a tank similarly sized to your freshwater tank.

Grey water comes from a variety of sources including your sinks, shower and caravan washing machine - essentially any wastewater that isn't from the toilet.

Many of the more expensive caravans and motorhomes have built-in grey water tanks. These are connected to the water system and divert greywater via a manually operated valve. External grey water tanks are also a common alternative for caravans.

You can pick up these tanks for quite a reasonable price. They are often sized at around 40 litres or so. Like the external freshwater tank, these are easily connected to your caravan. Then, you can wheel or carry your grey water tank back onto your van or to a safe disposal point.

Grey water tank

A modular grey water tank

Black Water Tanks

Nobody wants to think about this but it’s one of the most crucial pieces of kit in your van. The black tanks should only contain the solid and liquid waste from your caravan toilet as well as biodegradable toilet paper. Anything else can clog the tank and you don’t want to have to deal with that (trust me!).

Black tanks usually come in the form of a cassette for caravans. It’s easy to remove it and bring it to the waste disposal point. Brand leaders Dometic and Thetford provide 17-19 litre tanks.

Fixed black water tanks are common in campervans and RVs. It’s essential to use chemicals to regularly treat and clean the tank.

The Caravan and Motorhome Club of Australia (CMCA) have helped provide over 330 waste disposal points across the nation, so keep these in mind when planning your trip.

If you want more information about how your toilet integrates with your water system, check out this guide on how caravan toilets work.

Things To Remember

Stay Clean

Your water system will look after you if you look after it. Flush out your freshwater tank with an appropriate cleaning solution and treat your black and grey water tanks with chemicals regularly.

If you own a galvanised steel tank, some cleaners may not be suitable, so do your research.

Water Load

Before each trip, it may be tempting to fill your water tank to the brim. After all, water is like gold in Australia. But much like gold, water is extremely heavy.

While this extra load can stabilize your vehicle it will also increase your fuel consumption. It can also put your van over the towing capacity for your vehicle.

Be especially careful if you have a retrofitted grey water tank. If you fill your freshwater tank before you empty your full grey water tank, you may be adding a lot of extra weight to your vehicle.

Hopefully, you have a better idea of how your caravan water system works now. If you have any questions please comment below!

This article may contain affiliate links. I will earn a commission if you choose to purchase a product or service after clicking on my link. This helps pay for the cost of running the website. You will not be disadvantaged in any way by using my links.

Note that while every effort is made to ensure the accuracy of the information on this page, there may sometimes be errors. Check all specifications with the manufacturer before purchasing any product.

This article may contain affiliate links. I will earn a commission if you choose to purchase a product or service after clicking on my link. This helps pay for the cost of running the website. You will not be disadvantaged in any way by using my links.

Note that while every effort is made to ensure the accuracy of the information on this page, there may sometimes be errors. Check all specifications with the manufacturer before purchasing any product.


While Louis does most of his trips near his home in south-east Queensland, he has been camping as far afield as South America and Africa. He loves researching, testing and experimenting with camping gear whenever possible.

  • Hi If I have mains water connected to my van can I still pump rain water to my taps with thevpump? Regards Rob

  • I have just bought a Camec tank, but the outlets are about 10% of the depth of the tank up from the bottom meaning that I cannot access 10% of the water. To make matters worse the vent has a threaded moulding into the tank, again about 10% down. All up I have less than 80% of the tank capacity available! Does anyone know of tank fittings that allow use of the full tank capacity?

  • My caravan has 3 85l tanks, the first 2 pump through quite nicely. But the 3rd cavitates when needing to be used. I have noticed that the first 2 are connected by a pipe that runs at a level in line with where they discharge from the tank but the 3rd is plumbed to run up over the suspension and back down [higher than the tank]. Becaise it can’t gravity like the other 2 could this cause the problem?

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