Guides/Water Systems

Build Guide

Campervan Water Systems

Everything you need to know about planning and installing a water system in your van — from choosing the right tank and pump to plumbing, water heaters, and filtration.

Difficulty: Intermediate–Advanced Cost: £150–£1,500+ Time: 1–3 days

Tanks Pumps Water Heaters Filtration Installation Guide

A well-designed water system transforms a van conversion from a camping trip into a genuinely comfortable home on wheels. The difference between a basic sink-and-tank setup and a properly plumbed system with hot water is enormous in terms of daily comfort.

This guide walks through every component of a van water system — from choosing between internal and underslung tanks, to selecting the right pump and water heater for your needs, to a step-by-step installation guide.

Water Tanks: Internal vs Underslung

Internal Fresh Water Tank

£40–£150·10–60 litres typical

Best for: Weekend builds, micro/compact vans, budget builds

Pros

Protected from freezing
No drilling required under van
Easy to access and clean
Can be any shape to fit available space
Cheaper to install

Cons

Takes up valuable interior space
Heavier load inside van
Can be harder to fill (need to access interior)
Reduces living space

Underslung Fresh Water Tank

£80–£300·40–100+ litres typical

Best for: Full-time living, larger builds, LWB vans with good underbody clearance

Pros

Doesn't take up interior space
Can be larger capacity
Easy to fill from outside
Keeps weight low (better handling)
Professional finish

Cons

Risk of freezing in winter
More complex installation
Requires drilling/mounting under van
Harder to access for cleaning
More expensive

Grey Water Tank

£30–£120·10–40 litres typical

Best for: Full-time living, eco-conscious builds, campsite use

Pros

Catches waste water (required at some campsites)
Environmentally responsible
Prevents mess under van

Cons

Extra weight when full
Needs regular emptying
Additional plumbing complexity

UK Tip: CAK Tanks (caktanks.co.uk) are the go-to UK supplier for custom-shaped underslung and internal tanks. They make tanks to measure for specific van models — highly recommended.

Water Pumps

12V Submersible Pump

£15–£40Low (gravity-assist)

Pros

✓ Very cheap

✓ Simple to install

✓ Quiet operation

✓ Sits inside the tank

Cons

✗ Low pressure

✗ Not suitable for shower

✗ Can be unreliable long-term

Best for: Budget builds, sink-only systems

12V Pressure Pump (Shurflo / Flojet)

£40–£120Medium–High (20–60 PSI)

Pros

✓ Good pressure for sink and shower

✓ Auto-pressure switch

✓ Reliable and widely used

✓ Easy to install

Cons

✗ Can be noisy

✗ More expensive than submersible

✗ Needs accumulator tank to reduce cycling

Best for: Most van builds — the standard choice

12V Diaphragm Pump (Whale / Jabsco)

£60–£150Medium (20–40 PSI)

Pros

✓ Quiet operation

✓ Self-priming

✓ Good for remote tank locations

✓ Reliable

Cons

✗ More expensive

✗ Lower pressure than Shurflo

✗ Less common — harder to find parts

Best for: Builds where noise is a concern, remote tank locations

Water Heaters

Propex HS2000 / HS2211

LPG Gas Water Heater

£350–£500

✓ Fast heating

✓ Works off-grid (no shore power needed)

✓ Reliable UK brand

✓ Compact size

✓ Can also heat the van

✗ Requires LPG gas supply

✗ Gas safety considerations

✗ More expensive upfront

Best for: Off-grid builds, full-time living

Instant Gas Water Heater (Eccotemp / Camplux)

Propane Instant Heater

£60–£200

✓ Cheap

✓ Instant hot water

✓ Compact

✓ Good for outdoor showers

✗ Requires propane cylinder

✗ Not weatherproof for indoor use

✗ Basic quality

✗ Not suitable for indoor plumbing

Best for: Budget builds, outdoor shower setups, weekend use

Water Filtration

Inline Sediment Filter

Recommended

Fits in the supply line before the pump. Removes particles and debris. Essential for protecting the pump. Replace every 3–6 months.

£5–£20

Carbon Block Filter

Removes chlorine, taste, and odour from tap water. Fits inline after the pump. Good for improving taste of mains water.

£20–£60

UV Steriliser

Kills bacteria and viruses in the water supply. Important if filling from non-mains sources (streams, rivers, questionable taps).

£60–£200

Step-by-Step Installation Guide

Plan Your Water System

Sketch out your complete water system before buying any components. Decide: fresh water tank location (internal or underslung), grey water tank location, pump position, water heater position, sink location, and whether you want a shower. This planning stage prevents expensive mistakes.

Install the Fresh Water Tank

For internal tanks: position in a low, accessible location (under the bed or in a dedicated locker). Secure firmly — a full 40L tank weighs 40kg and will move dangerously if unsecured. For underslung tanks: mount using stainless steel straps and brackets rated for the full weight of the tank. Drill a fill port through the van body and fit a waterproof cap.

A full water tank is very heavy. Ensure mounting is rated for at least 3x the full weight to account for road vibrations and impacts.

Install the Water Pump

Mount the pump close to the fresh water tank (short suction line = better performance). Use rubber mounts or foam padding to reduce vibration noise. Connect the inlet to the tank and the outlet towards the sink/heater. Fit an inline strainer filter on the inlet side to protect the pump from debris.

Tip: Shurflo pumps are the most popular choice in UK van conversions. The 2088 series is a proven, reliable option.

Plumb the System

Use 12mm John Guest push-fit fittings and 12mm semi-rigid pipe for most of the system — these are easy to work with and leak-free. Run the pipe from the pump to the water heater (if fitted), then to the hot tap. Run a separate cold line directly from the pump to the cold tap. Use 15mm pipe for the heater connections if required.

Tip: John Guest push-fit fittings are the standard choice for van plumbing — no tools needed, very reliable, and easy to disconnect if needed.

Install the Water Heater

Position the water heater close to the sink to minimise the length of hot water pipe (reduces wait time for hot water). Follow the manufacturer's instructions carefully — gas and diesel heaters require specific ventilation and safety clearances. Electric heaters are simpler but require a 240V shore power connection or large 12V battery bank.

Gas appliances must be installed correctly and safely. If in doubt, have a qualified gas engineer check your installation.

Install the Sink and Taps

Cut the sink opening in your worktop. Fit the sink and taps before fitting the worktop if possible — much easier to access. Connect hot and cold supply lines to the tap. Connect the sink waste to your grey water tank or a suitable drain point.

Install the Grey Water Tank

Position the grey water tank below the sink (gravity drainage). Connect the sink waste pipe to the tank inlet. Fit a drain valve at the lowest point of the tank for emptying. Mark the tank clearly so you don't forget to empty it.

Connect the 12V Electrics

Connect the pump to your 12V leisure battery circuit via a fuse (5A inline fuse close to the battery). Most pumps draw 3–5A when running. Wire to a switch on your electrical panel. Test the system thoroughly before fitting interior panels — check every joint for leaks.

Always fuse 12V circuits close to the battery. Test for leaks before fitting interior panels — water damage behind panels is very difficult to fix.

Insulate Water Pipes

In the UK, water pipes in uninsulated areas of the van can freeze in winter. Wrap exposed pipes with foam pipe lagging. Pay particular attention to underslung tank connections and any pipes running through uninsulated floor areas. Consider a tank heater pad for underslung tanks if you plan to use the van in winter.