Water in your camper: how big, how plumbed, and how to keep it drinkable

How many litres you need

Without an indoor shower, two people use ten to fifteen litres a day: cooking, washing up, teeth, coffee, and a small wash. With an indoor shower that doubles. So the question is not how much water you use but how many days you want between fill-ups.

Where the tank belongs

• As close to the middle of the van as possible, between the axles. A hundred kilos at the back noticeably changes how the van behaves in a crosswind.
• As low as possible. Water carried high acts like a pendulum in corners.
• Inside, not slung under the floor — unless you buy a heated tank. An outside tank freezes, and a frozen tank splits.
• Reachable. You must be able to get a hand inside to clean it, and that needs a generous inspection opening.

The installation, tank to tap

1. 01

   Filler and breather

   Besides a filler, every tank needs a breather. Without one the air cannot escape while filling — the water burps back — and the tank pulls a vacuum while being pumped out, collapsing inwards. Route the breather up and then down to the outside so water does not slosh out while driving.

2. 02

   Pump and accumulator

   A pressure pump with a pressure switch is simplest: open the tap, the pump runs. Put a small accumulator after it and the pump stops cycling on every drip, giving a steady stream instead of a pulsing one. Mount the pump on rubber — it is the loudest component in the whole camper.

3. 03

   Filter and check valve

   A coarse filter before the pump keeps out grit that would otherwise wreck the pump body. A check valve stops the line draining back into the tank when the pump is off.

4. 04

   Pipework

   Use drinking-water hose that does not taint the taste, routed with as few bends as possible and no low loops — water stands in such a loop when you drain, and that is exactly where biofilm starts. Secure every joint with a clip; vibration does the rest.

5. 05

   Drain at the lowest point

   This is the most often forgotten part and the most important one in the whole system. Without a drain at the genuinely lowest point you cannot empty the system for winter, and freezing water will split your tank, pump and pipework in a single night.

6. 06

   Grey water

   Everything that goes in comes back out. A grey water tank of roughly the same capacity, with a drain valve you can operate without crawling under the van. In many places you may not simply let grey water run onto the ground.

Keeping it clean, and why you must

A camper water tank is warm, dark and still: precisely the conditions bacteria like. A biofilm forms on the inner wall, a thin slimy layer that rinsing does not remove and that makes the water taste stale. In water standing at temperature for more than a few weeks, legionella is a genuine risk — that is not scaremongering but the reason the rules for fixed installations exist.

• Never leave the tank half full between trips. Empty and dry, or full and in use.
• Clean twice a year, and always at the start of the season. Fill the tank, let a product intended for drinking-water systems work, then flush through completely twice — including through the taps, because the pipework and mixer are as much part of it as the tank.
• Use a product intended for drinking water. Household bleach and denture tablets circulate online as tips; the first leaves taste and residue, the second was never made for this.
• Rinse after cleaning until you smell nothing. What you can smell, you will later taste.
• Fill preferably from a tap in daily use, not from a hose that has been lying in the sun.

Getting through winter

There is only one reliable method and that is completely empty. Drain the tank, run the pump dry until air comes through, set every tap open in the middle position so both hot and cold lines empty, and leave them open. Antifreeze in a drinking-water system is not a solution: you never get it fully out again. A pipe with a low loop you cannot reach is where you find out next spring.

Work through your payload