Campervan Water Tank : A Practical Guide to Choosing, Installing, and Maintaining

A campervan water tank is the heart of your mobile plumbing system. It’s the reservoir holding all the fresh water you’ll need for drinking, cooking, and washing up. But it’s only one part of the puzzle. It works hand-in-hand with a grey water tank (for your used water) and a network of pipes and a pump that get the water where it needs to go. Getting this balance right between water capacity, the weight it adds to your van, and the space it takes up is one of the most critical decisions in any build.

Your Campervan Water System Explained

Think of your campervan’s water system as its lifeblood. It’s a self-contained circuit designed to give you the simple comforts of a home kitchen and bathroom, whether you’re parked up in a remote forest or overlooking a Cornish beach. Without a solid water system, any dreams of proper off-grid adventures get a lot more complicated.

Figuring out how it all fits together is the first step. Once you get your head around the basics, you can build a setup that perfectly suits the way you travel.

At its core, the whole thing is surprisingly straightforward and relies on just a few key players. Each bit has a specific job to do, and making sure they all work together is the secret to a leak-free, reliable system that delivers clean water whenever you need it.

The Three Core Components

Every campervan water system, from the simplest to the most complex, is built from three fundamental parts:

• Freshwater Tank: This is your clean, drinkable water supply. It’s the source for everything from your morning cuppa to rinsing your dinner plates. The quality of this tank and the pipes connected to it directly affects the safety and taste of your water.
• Grey Water Tank: As soon as you’ve used that fresh water—whether it’s from the sink or a shower—it becomes ‘grey water’. This tank’s job is to collect and hold all that waste until you can get rid of it responsibly at a proper service point.
• Pipes and Pump: This is the network that connects it all. A 12V water pump is the muscle, pulling water from the fresh tank and pushing it through food-grade pipes to your tap the moment you turn it on.

Your water tank is more than just a container; it’s your key to freedom. The right size and setup determine how long you can stay off-grid, transforming a weekend camper into a true adventure vehicle capable of exploring the UK’s wildest corners.

It’s also worth knowing a bit about water quality. You’re looking to fill your tank with potable water – a fancy way of saying it’s safe for us to drink. It’s a common misconception that all purified water is good for you; for example, there are some pretty compelling reasons why ultrapure water is not suitable for drinking. Keeping these basics in mind will help you make much better decisions as we get into the nitty-gritty of choosing the right bits for your build.

Choosing the Right Water Tank for Your Van

Picking the right water tank for your campervan is a bit like deciding between a permanent home and a nomadic lifestyle. One gives you stability and integrated convenience; the other offers flexibility and dead-simple practicality. Your choice between a fixed, plumbed-in tank and a few portable containers will genuinely shape how you use your van, from doing the washing up to where you can top up on water across the UK.

There’s no single “best” answer here, just what’s best for your build and how you travel. A solo weekender in a little VW Caddy has totally different water needs than a family of four planning to disappear into the Scottish Highlands for a month. Getting your head around the practical trade-offs is the first real step to building a water system that just works without causing you a headache.

Fixed vs Portable Tanks

The big decision boils down to fixed tanks versus portable water carriers. Fixed tanks get properly plumbed into your van, either mounted internally (often tucked away inside a bench seat or a cupboard) or underslung beneath the chassis to save precious interior space. Portable carriers are basically big, tough jerry cans you lug around by hand.

Fixed tanks are all about creating an integrated system. They connect directly to your water pump, your tap, and maybe even a hot water heater, making it feel much more like a proper home. This setup is brilliant for larger conversions and for anyone who wants the convenience of a big water supply for longer off-grid stints.

Portable tanks, on the other hand, are the champions of flexibility. Need to fill up from a slightly dodgy-looking tap halfway down a farm track? No problem, just carry the container over. Worried about running out? Just keep a spare full one in the back. They are perfect for simpler builds, smaller vans where every inch of space is sacred, and for anyone who isn’t keen on drilling holes in their van.

Your choice of tank dictates your entire refill strategy. With a fixed tank, you have to be able to drive your whole van right up to the water source. With portable tanks, you just need to get the container to the tap, which gives you far more freedom.

Understanding Tank Materials

No matter which type of tank you go for, the material it’s made from is non-negotiable. It must be food-grade plastic. This is the only way to guarantee that no nasty chemicals will leach into your drinking water, keeping it safe to drink and free of that grim plastic taste.

Keep an eye out for tanks made from materials like:

• High-Density Polyethylene (HDPE): This is the most common one you’ll see. It’s durable, safe, and perfect for water storage.
• Polypropylene (PP): Another excellent food-safe plastic known for being rigid and coping well with temperature changes.
• BPA-Free Plastics: Always double-check for a “BPA-Free” label. Bisphenol A is a chemical you definitely want to avoid.

Any reputable supplier will make it crystal clear if their tanks are suitable for potable (drinking) water. Never, ever be tempted to repurpose an old container that once held chemicals or anything other than food-grade liquids – you can never be certain you’ve cleaned out all the residue.

Fixed vs Portable Water Tank Comparison

To help you decide, let’s break down the real-world differences. Think honestly about your DIY skills, how long your average trip is, and how much space you can realistically give up for your water system.

This isn’t just about how many litres you can carry; it’s about how you’ll live with it day-to-day. A massive underslung tank is fantastic until you find the only available tap is down a footpath where you can’t take your van. On the flip side, doing multiple trips back and forth with a pair of 25-litre portable cans can quickly get old.

This table gives you a straight-up comparison to help you weigh the pros and cons for your own adventures.

Ultimately, the best choice aligns with your priorities. If you crave a seamless, home-like experience and have the budget and skills for the installation, a fixed tank is hard to beat. But if you value simplicity, flexibility, and a lower initial cost, portable containers are a brilliant and practical solution that has served van dwellers well for decades.

Calculating Your Ideal Tank Size

Figuring out the right size for your campervan water tank feels like a dark art, but it’s actually just a bit of simple maths. The goal is to hit that sweet spot: enough water to stay comfortably off-grid, but not so much that you’re hauling around unnecessary weight. Get it wrong, and you’ll either be constantly hunting for a tap or sacrificing precious payload and fuel economy.

Before you even think about numbers, you need to be brutally honest about how you use water. Are you a minimalist who just needs a splash for a cuppa and to brush your teeth? Or are you planning on proper hot showers after a muddy hike? Every drop adds up, and more importantly, every litre adds a kilogram to your van’s weight.

Estimating Your Daily Water Use

First things first, let’s break down your daily routine. A solo traveller on a quick weekend jaunt has completely different needs to a couple living in their van full-time. The key here is realism.

Think about all the ways you’ll get through your water supply:

• Drinking and Cooking: How many litres do you actually drink in a day? Don’t forget water for tea, coffee, and cooking things like pasta or rice. It adds up faster than you think.
• Personal Hygiene: This covers the basics – brushing your teeth, washing your face, and rinsing your hands throughout the day.
• Washing Up: Doing the dishes after a meal can be surprisingly thirsty work, especially if you’re not disciplined with water-saving techniques.
• Showering: This is the big one. A quick 90-second rinse-off is one thing; a long, hot shower is another beast entirely. If you’re planning an onboard shower, your required tank capacity will shoot up.

For those planning to add a shower to their build, it’s worth knowing how much different types can drain your supply. Our detailed guide on choosing a portable camping shower can help you pick a water-efficient option that works for your setup.

To give you a clearer picture, here’s a rough breakdown of what common activities consume.

Estimated Daily Water Usage Per Person

This table provides a realistic look at how much water different activities use per person, helping you make a more accurate calculation for your tank size.

Remember, these are just estimates. If you’re a coffee fiend or love a good scrub-down, adjust your numbers upwards!

The Simple Calculation for Tank Size

Once you’ve got a rough idea of your daily usage, you can plug it into a simple formula. This will give you a solid baseline for the minimum freshwater capacity you’ll need for your planned trips.

(Litres per person per day) x (Number of people) x (Days off-grid) = Ideal Tank Size

For example, a couple who reckon they use 15 litres each per day and want to last for three days without refilling would need a 90-litre tank (15 x 2 x 3 = 90).

In the UK, it’s common to see campervan water systems with tanks ranging from 20 to 100 litres. A good rule of thumb from experienced UK motorhomers is to budget around 2 litres per person just for drinking and another 10-12 litres for essentials like washing up and brushing teeth. Based on that, a 20-40 litre tank can be plenty for solo travellers or couples on short trips who aren’t showering in the van.

The Critical Role of Weight and Payload

Now for the reality check. Water is heavy. One litre weighs exactly one kilogram. That shiny new 100-litre tank adds 100 kg to your van before you’ve even packed your clothes, food, or gear. This has a massive impact on your vehicle’s payload.

Every van has a Maximum Authorised Mass (MAM), which is the total legal weight it can be on the road, including the van, passengers, and everything you’ve crammed inside. Going over this isn’t just illegal; it’s downright dangerous. It messes with your van’s braking, handling, and stability.

A massive water tank might feel like a luxury, but it could easily be the thing that tips you over your legal weight limit. It also hammers your fuel efficiency, meaning more stops at the petrol station. This is why you have to strike that careful balance between off-grid freedom and keeping your van light and legal.

A Practical Guide to Installing Your Water System

Right, you’ve picked your tank and worked out the perfect size. Now for the fun bit: getting your hands dirty and actually installing the thing. This is where all those separate components – the tank, the pump, the tap – come together to form a proper, working water system.

It can feel a bit intimidating, especially if it’s your first build, but trust me, it’s not as complex as it looks. By breaking it down into simple, logical steps, the whole process becomes completely manageable. We’ll walk through everything you need to know, whether you’re fitting a tank inside a bench seat or slinging one underneath the van.

Essential Tools and Components Checklist

Before you even think about drilling a hole, get everything you need laid out and ready to go. There is nothing more soul-destroying than having to stop mid-job for a frantic dash to Screwfix because you’ve forgotten something. A bit of organisation now will save a massive headache later.

Here’s a typical shopping list for the job:

• Components:
  • Your freshwater tank
  • A 12V water pump (either submersible or a diaphragm type)
  • Food-grade water hoses (usually 12mm in the UK)
  • Hose clips (often called Jubilee clips)
  • An external water filler point and cap
  • Breather/vent hose
  • The tap for your sink
  • Any pipe fittings you might need (elbows, straight connectors)
  • PTFE tape to make sure threaded connections are watertight
• Tools:
  • A drill with a good set of bits
  • A hole saw for cutting the filler point hole
  • Screwdriver set
  • Spanners or an adjustable wrench
  • Pliers or grips for tightening the hose clips
  • Silicone sealant (make sure it’s food-safe if used inside)
  • A sharp knife or proper pipe cutter for clean cuts

Installing the Core Plumbing Components

The heart of the job is connecting the tank, pump, and tap. The exact method changes slightly depending on your pump choice – submersible or diaphragm – but the core principle of creating secure, leak-free connections is the same for both.

A submersible pump setup is beautifully simple. The pump itself just gets dropped straight into your water tank. The power cable and the outlet hose then feed out through the top of the tank and run directly to your tap. Job done.

An external diaphragm pump involves a little more plumbing. You’ll need one hose running from an outlet at the bottom of the tank to the pump’s inlet. Then, a second hose runs from the pump’s outlet all the way to your tap. These pumps are self-priming, which is a fancy way of saying they are powerful enough to suck the water up from the tank.

Top Tip: When you’re tightening hose clips, you’re aiming for ‘firm but not crushing’. If you go overboard and crank them down too hard, you can easily crack the plastic fittings on your tank or pump, creating a weak spot that’s guaranteed to leak down the line.

The process of calculating your required tank size involves balancing daily water usage against the number of people and planned days off-grid.

This visual guide shows that your total required capacity is a direct product of these three key factors.

Securing Your Tank and Running Hoses

Whether your tank lives inside a cupboard or is mounted underneath the chassis, it absolutely must be secured so it cannot move an inch. A full 70-litre tank weighs a hefty 70 kg – you do not want that flying around the van when you brake hard. Use heavy-duty straps, build a custom wooden frame, or buy purpose-made brackets to lock it firmly in place.

When you run your water hoses, try to keep the routes as short and direct as you can. Avoid any sharp kinks or bends, as they’ll restrict the water flow and put a strain on your pump. To keep them tidy and safe, use P-clips to secure the hoses to the van’s walls or floor every foot or so. This stops them from chafing on sharp edges or sagging over time.

If you’ve got an underslung tank, make sure any hoses running outside the van are properly protected from road debris. Keep them well away from hot parts like the exhaust or any moving suspension components.

Wiring Your 12V Water Pump

The final piece of the puzzle is getting power to your pump. Every campervan water pump runs on 12V DC power from your leisure battery. It’s a simple electrical circuit, but it’s one you need to get right for it to be safe.

1. Switch Integration: The neatest way to wire it is through a microswitch that’s built into your tap. When you turn the tap handle, the switch closes the circuit, the pump kicks in, and water flows instantly. Simple.
2. Fuse Protection: This is non-negotiable. You must put an inline fuse on the positive wire, as close to the battery as you can. This protects the pump and wiring if there’s ever a short circuit. A 5-amp or 10-amp fuse is usually spot on, but double-check the specs for your specific pump.
3. Correct Polarity: It’s just like wiring anything else to your 12V system. Connect the positive (red) wire from the pump to your fused supply, and connect the negative (black) wire to a good chassis ground point or your negative busbar.

Getting the wiring right means your pump will work reliably and, more importantly, safely. Once it’s all hooked up, pop a little water in the tank, switch on the power, and check every single connection for drips before you call it a day.

Managing Grey Water Responsibly in the UK

Proper van life in the UK isn’t just about finding incredible park-ups; it’s about leaving them exactly as you found them. This is where your grey water tank becomes one of the most important, and often overlooked, bits of your van’s water system. It’s your responsibility to make sure the water you’ve used for washing up, brushing your teeth, or showering is collected and dealt with properly.

Think of it as the other half of the water equation. For every litre of fresh water you bring on board, you’re going to create a litre of grey water. It’s a simple one-in, one-out system. This is why the golden rule is to have your grey water tank match the size of your freshwater tank. A 70-litre fresh tank should be paired with a 70-litre grey tank. This simple bit of planning means you’ll never be forced to leave wastewater behind simply because you’ve run out of space.

Why Proper Disposal Is So Important

It’s easy to think, “It’s just a bit of soap and water,” but the reality is that even small amounts of waste can have a big environmental impact. All the soaps, detergents, food scraps, and toothpaste in your grey water can seriously harm local ecosystems, pollute streams, and affect wildlife that relies on those water sources.

Discharging grey water isn’t a victimless act. Even so-called ‘eco-friendly’ or biodegradable soaps need to be broken down by soil. If they go straight into a stream or loch, they can cause real harm. The whole ‘leave no trace’ philosophy is fundamental to keeping our wild camping spots open, beautiful, and available for everyone to enjoy.

Looking after your waste isn’t just about being a good person; it’s a legal requirement in many parts of the UK. Knowing where and how to empty your tank is a non-negotiable part of van life.

UK Regulations and Where to Empty Your Tank

In the UK, there are clear expectations for how we manage waste from campervans and motorhomes. Regulations introduced back in 1998 required UK ports and marinas to provide proper waste disposal facilities, and this has influenced the design of modern campervan systems. It’s why you often see built-in grey water tanks with capacities between 50-100 litres – enough to comply on longer trips without needing to empty every day.

So, where can you actually get rid of your grey water?

• Designated Campsite Service Points: This is the easiest and most common option. Pretty much every official campsite has a dedicated motorhome service point with a big drive-over drain specifically for grey water.
• Public Service Points (Aires): While they’re not as common in the UK as they are in France or Spain, dedicated ‘Aires’ or motorhome service points are popping up. If you find one, it will always have waste disposal facilities.
• Home Drains: You can legally and safely empty your grey water down a sewer drain at your own home. The crucial thing to remember is never empty it into a rainwater or storm drain on the street. Those drains flow directly into rivers and streams, which is exactly what we’re trying to avoid.

Keeping Your Grey Water Tank Fresh

One of the most common complaints about grey water systems is the smell. As tiny food particles and soap scum start to break down in the tank, they can kick up some pretty unpleasant odours that sneak back up your plughole. Thankfully, it’s dead easy to manage.

1. Use a Sink Strainer: This is the single most effective thing you can do. Catching food scraps before they go down the drain stops the problem at the source.
2. Regularly Use Tank Fresheners: There are specialised products for grey water tanks that use enzymes to break down the gunk and neutralise smells. A capful every now and then makes a huge difference.
3. Clean it Out Periodically: A couple of times a year, give the tank a proper flush-out with a dedicated tank cleaner to get rid of any sludge that’s built up over time.

Of course, managing your waste water is just one part of the puzzle. For a complete guide to van life sanitation, have a look at our rundown of the top 10 portable toilets for campervans in the UK.

Keeping Your Water System Clean and Winter-Ready

Think of your campervan water system as the lifeblood of your setup. It’s where your drinking water comes from, so keeping it clean isn’t just a good idea—it’s absolutely critical for your health on the road. Proper maintenance also stops you from facing costly damage, especially when the notoriously damp and frosty UK winter rolls in.

Let things slide, and you’ll get a nasty build-up of biofilm, bacteria, and algae. That means foul-tasting water at best, and a trip-ruining illness at worst. A single freezing night can be even more dramatic, bursting pipes and turning your pride and joy into a very expensive, very soggy mess.

Regular Cleaning and Sanitising

A simple, consistent cleaning schedule is your best weapon against contamination. The aim is to give the whole freshwater system a proper flush-out, from the filler cap all the way through to the tap, making sure every drop of water is safe.

Plan to fully clean and sanitise your campervan water tank at least twice a year. I do mine once at the start of the main travel season and again just before tucking the van away for winter. If your van has been sitting idle for a few months, or if you notice any weird taste or smell from the water, that’s your cue to do an immediate clean.

A clean water system is a safe water system. Treat it like a spring clean for your kitchen; it’s a deep clean that keeps everything hygienic and ready to go. It’s a small bit of effort that pays off massively in peace of mind.

For a full walkthrough of the process, check out our detailed guide on campervan water tank cleaning. It covers the exact products and steps you need to get the job done right. This isn’t a task to skip.

A Step-by-Step Guide to Winterising

For any UK van owner, winterising is a non-negotiable yearly chore. Water expands by about 9% when it freezes, creating huge pressure that will easily split plastic fittings and burst your hoses. The whole point of winterising is to get every last drop of water out of the system before that can happen.

1. Drain Your Tanks
First things first, completely empty both your fresh and grey water tanks. Just open up the drain taps and let gravity do its thing. I usually drive the van onto levelling ramps to give it a slight tilt, making sure all the water flows towards the drain.

2. Empty the Pipes and Pump
With the tanks empty, switch on your 12V water pump and open every tap in the van (both hot and cold, if you have them). Let the pump run until it’s just spitting and spluttering air. This forces the last of the water out of the pipework.

3. Clear the Water Heater
If you have a water heater, it will have its own drain valve or bung. It is absolutely vital to drain this completely. These units are especially vulnerable to frost damage and are seriously expensive to replace.

4. Final Checks
Last step: leave all the drain valves and your taps in the open position over winter. This allows any condensation or leftover droplets to escape and acts as a final failsafe if you missed any water. For more great advice, it’s worth reading up on these tips on preventing frozen pipes to avoid any nasty surprises.

Your Burning Questions Answered

When you’re knee-deep in plumbing fittings and diagrams, a few questions always seem to pop up. Getting these sorted is the difference between a reliable water system and one that causes you grief on the road. Let’s tackle some of the most common queries I hear from fellow van builders.

Think of this as the practical advice you’d get from a mate who’s already made all the mistakes. Getting this stuff right from the start means fewer problems down the line, letting you get on with the actual adventure.

How Often Should I Actually Clean My Water Tank?

Realistically, you should give your freshwater tank a proper clean and sterilise at least twice a year. My routine is simple: once in the spring before the main travel season kicks off, and once in the autumn before the van gets parked up for longer periods. This stops any nasty biofilm or bacteria from getting a foothold.

That said, trust your senses. If you ever notice a funny taste or smell coming from your tap, that’s your cue to clean the system immediately, no matter when you last did it. The same goes if the van has been sitting unused for a few months. Just make sure you use a food-safe cleaning solution and flush the entire system through afterwards, not just the tank.

Is It Actually Safe to Drink Water Straight From the Tank?

Yes, absolutely – providing you do it right. It’s perfectly safe to drink water directly from your campervan tank as long as you tick two crucial boxes: the tank and all your pipework must be made from food-grade materials, and you have to stick to that regular cleaning schedule we just talked about.

For an extra layer of confidence, most of us fit a simple inline water filter just before the kitchen tap. They’re cheap, easy to install, and brilliant at removing things like chlorine, bits of sediment, and other impurities your water might pick up from dodgy fill-up sources around the UK. It’s a small price to pay for knowing your water is always fresh and clean.

Your campervan water system is only as clean as its dirtiest part. A proper clean isn’t just about the tank; it’s about flushing the whole network—pump, pipes, and taps—to make sure every drop that comes out is safe to drink.

What’s the Best Water Pump for a Van?

You’ve basically got two choices here, submersible pumps or diaphragm pumps. Each one has its place.

• Submersible Pumps: These are the budget-friendly, quiet option. You just drop them directly into your water tank, making for a ridiculously simple installation. If you’ve just got a basic setup with a sink, a submersible pump is a great choice.
• Diaphragm Pumps: These are mounted outside the tank and are much more powerful. They give you a consistent, pressurised flow that feels just like a tap at home, which makes them the go-to option for any system that needs to run both a sink and a shower.

In the van life world, brands like Shurflo and Whale have earned their reputation for being tough and reliable. You really can’t go wrong with either for a solid, long-lasting build.

At The Feral Way, we provide tested, no-nonsense guides for UK campervan conversions and travel. Find everything you need for your build at https://www.theferalway.com.