How to: install a camper van water system

Updated: Sep 23

Installing the plumbing in your van can be a daunting task - get it wrong and you'll be left with leaks and a damp van! The first thing you will need to decide when planning your DIY camper van water system is what aspects you want to include in your system.

Our own van conversion water system is comprised of:

• A 70L fresh water tank

• A Shurflo water pump and Fiamma accumulator

• A tap and sink with running water (cold only)

• An instant hot water outdoor shower (blog post on our shower setup coming soon!)

We decided to keep our water system relatively simple to minimise complexity. If you want to have hot water coming from your kitchen tap, or if you're installing an indoor shower in your van, your system will need to include a boiler with a flue that can vent outside. Because our shower is an outdoor shower, this made our system much more simple - the shower is mounted next to the back doors and will only ever be used with the back doors open, so this meant we didn't need to build in a flue.

Contents of this post:

• How to size your camper van water tank

• Grey water tanks

• Our camper van water system diagram

• What components do you need for your camper van water system?

• Step by step installation guide to plumbing in your water system

• Wiring in the water system electrics

What size water tank should you install in your camper van conversion?

When sizing your water tank, you should consider a few different questions:

  • What is your general water usage (i.e. do you have a shower, how often will you use it etc)?

  • How often will you be able to refill your tank (i.e. how much time are you planning on spending off grid)?

  • How much do you want to spend (the bigger the tank, the more expensive)?

  • How much space do you have (i.e. where will you mount it)?

  • Do you need to consider weight (i.e. do you have a big van that will be close to 3.5T)?

It's worth trying to calculate how much water you think you will use. People are meant to drink 2 litres of water per day. You will also use water for doing the dishes, washing clothes, washing yourself, and this all adds up. It's really important when you're living in a van to be frugal with water and not just use it as you would at home. Below is a table of our estimated weekly water usage for the 2 of us to give you a bit of an idea.

This works out at around 15L per day for 2 of us, which means we will need to fill our 70L tank up every 4-5 days.

Obviously usage will vary massively from person to person - if you have an indoor shower in your van that you use daily, you will likely need a bigger tank, or to fill up every day or 2. If you plan on staying mainly in campsites where you will be able to fill up regularly, it makes sense to have a small tank. However, if you want to be able to go off grid for several days at a time, you'll need to make sure your tank is big enough for your usage.

Once you have worked out your usage and you know how often you will need to fill up, you can start to work out what size tank you might need. With water tanks, it's not just a case of buying the biggest thing you can for a couple of reasons. Firstly, water weighs a lot - 1 litre of water = 1kg, which means if you have a 200L tank that's an extra 200kg you're carrying around when it's full! The other reason is that a bigger tank will be more expensive, so it's best to work out what size you think you will actually need rather than just buying the biggest thing possible.

We installed the 70L Fiamma water tank, however we would not recommend this tank to others. It does not have a lot of the inlets in useful places, and if we were to do it again, we would get a custom tank made which sits over the wheel arch. These are good as they utilise space which is otherwise quite hard to use.

It is also possible to install an underslung water tank on the bottom of your van which will save valuable room inside, but this might not be the best choice if you're planning on spending time in colder snowy climates where the water could freeze.

Grey water tanks

We also chose not to install a grey water tank. Grey water tanks are used for 'dirty' water from the shower and sink, and a lot of people who plan on spending a lot of time on a campsite will have them so as to not drain their water straight onto a pitch.

As we plan on free camping 99% of the time we're in our van, and our grey water will only be coming from our sink, we didn't feel the need to install one. We use eco-friendly washing up soaps to make sure we're not putting any harmful substances into the environment, and we also have a strainer in our sink to ensure no food waste ends up outside.

If you don't want to install a grey water tank but you plan on spending some time on campsites, you can always leave a container underneath your waste water pipe to collect the grey water and dispose of it before you leave.

If you do want to install a grey water tank because you will be spending a lot of time on campsites or stealth camping in cities, make sure to consider the size that will be right for your requirements - how often you will be able to empty it, and how big a factor cutting weight in your build is will affect your choice. You will also need to consider where to mount it - often people mount this directly under their sink so the waste pipe can go straight into it, and it's easy to access for emptying.

Our camper van water system diagram

Our campervan water system, including a tap and an outdoor shower

Our system consists of:

  • Water coming in via a water inlet point in our boot

  • Water going out via our sink and our outdoor shower

We chose not to install a boiler that we would need to vent out via a flue, so we just have cold water going to our tap. Our outdoor shower is an instant water heater connected to our LPG tank.

What components do you need?

Before you start plumbing in your water system, you will need to make sure you have all of the right components. Below is a list of all of the components we bought (links are Amazon & eBay affiliate links that will earn us a small commission at no extra cost to you).

Main components:

Hose, connectors & accessories:


Step by step guide to Plumbing in your water system

Firstly, you will need to mount your water tank. The method of doing this will vary based on your tank, but ours came with some threaded bar that uses nuts and washers to attach it. We mounted our tank onto a piece of ply on the side wall by drilling some holes in it and attaching the threaded bars using a washer and a nut. At this point the ply was fixed to the wall, and then we could move the water tank into place and attach it by screwing up the other washers and nuts by the tank.

When mounting your fill point, it's really important to mount it much higher than your tank, and ideally a bit of a distance away from it. This was another job that we would do differently next time - our fill point is right next to our tank, which means that when the tank is full and we go up a steep hill, water starts trying to splosh back out of the fill point. As long as you have a bit of a height drop and some distance, this won't be an issue.

We chose to mount our water inlet to some ply in our boot, so we wouldn't have to drill any more holes in the side of the van, but a lot of people do mount their fill points on the outside. Once you have attached your inlet either to some ply inside or to the outside of your van, you will need to use some convoluted hose that matches the size of your inlet and attach it using jubilee clips. We then used a water tank hose connector that matched the size of our hose to connect to the water tank.

As we mentioned before, the tank did not have many useful prebuilt inlet spots, so we had to drill our own to attach the tank connector. We then used a lot of silicone to ensure we wouldn't have any leaks.

When you purchase your water inlet, you will need to make sure it comes with a little bung that can be removed. Once you remove this bung, it lets the water system 'breathe'. If you do not have this, air pressure will build up in the system essentially creating a vacuum (think about what happens when you drink from a plastic water bottle and you don't let any air back in).

Once the tank and inlet were installed, we then used another tank connector to attach our water pipe to the water tank. We used 12mm food grade water pipe, which works really well for this purpose. Remember to install this at the base of your water tank so that you can access all of the water in your tank.

The water pipe is then connected to the water pump via a lever ball valve. This means that we ever have a leak in our system, we can isolate the water before it goes into the system. We attached the pipe to the lever ball valve and the pump using jubilee clips. The water pump is then connected to the accumulator in the same way. The accumulator is used to even the flow of the water, so that the water doesn't splutter as it comes out of your tank.

Once the water comes out of the accumulator, we used a T piece to split the pipe in 2, so that it can feed both the shower and the sink. You can use either brass or plastic for these connectors - we chose to use brass, but the plastic connectors work well too. Once again the pipe is connected to these using jubilee clips.

The pipe which leads to the shower simply needed pushing onto a female fitting which was already connected to the shower and tightening with another jubilee clip.

The pipe which leads to the sink was then split using another T piece, as the sink has 2 connections (usually used for hot and cold). As we don't have hot water going to our tank, we just connected both sides to the cold water coming from the pump. Alternatively you could blank off one of the connections, but it would mean that one of your taps/half of your mixer wouldn't work, so we preferred to connect both to the cold.

We used a 12mm barb to 1/2" BSP fitting to connect the pipe to our tap. The BSP size can vary depending on your tap, so make sure you double check before you buy anything.

Once all of the water is connected, you'll just need to connect some pipe to the waste in your sink. We used a 1 1/4" waste trap to 40mm pipe connector, but once again this size will vary depending on the waste on your sink, so make sure to check this. The waste trap is flexible so that you can create a U bend, which is important to do to stop smells (the water sitting in the U bend stops any smells from entering the van).

Because we have a large domestic sink with a large waste, it sits very low and quite far forwards. We used a waste trap with long bellows so that we could create a shallow U bend to run the rest of our pipe at the back of the cupboard and maximise space.

The waste trap is then connected to 40mm rigid pipe via a 135° bend connector, and then another piece of 40mm pipe is connected via another 135° bend connector so the pipe is going straight down. For us, this goes straight out the bottom of the van, but if you are connecting a grey water tank, this would be connected at this point via a tank connector.

Wiring up the water system electrics

To get your water system fully up and running, there are a few components you will need to connect to your electrical system (for more information on electrics, read our blog post on how to wire up your camper van electrical system). We connected our 12V water pump to our 12V fuse box via a switch so that we could easily turn it off when not in use.

Our Camplux instant hot water shower runs off LPG and only requires a spark to ignite, and this is powered by 2 D size batteries, so doesn't need to be wired into the electrical system.

We installed 2 float switches in our water tank, so that we would be able to see the water level of the tank, and know when the tank was under 1/3 full and would shortly need filling up. Each float switch was connected to the 12V fuse box via a blue LED. When the tank is full, the float switch is in a 'closed' position meaning that the circuit is completed and the LED lights up. As the tank empties, the float switch 'opens' which breaks the circuit, turning off the LED.

We mounted both LEDs along with the switch to control the water pump into a little housing that we made from wood and painted, and this lives in our electrical system area underneath one of our bench seats. We have easy access to this area by lifting up the seat, so we can easily turn the pump on and off and check the water level.

Float switches aren't necessarily the best option though, as they give you a very un-detailed view. In our system with 2 float switches and a 70L tank, there is a margin of almost 25L, which means when 1 LED is on, you could have anywhere from 25L to almost 50L of water in your tank! To get a much more accurate picture, you could use a clear water tank and mount it somewhere easily accessible, so you can literally just see inside the tank.

Thanks for reading, if you have any questions feel free to drop us a message on here or via Instagram!

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