Camper van water systems, from tank to tap

A camper van water system is four things in a line: a tank you fill, a pump that pressurises it, pipe that carries it to the taps, and a drain that has to go somewhere. Sizing it is where most first vans go wrong, because the number that decides tank capacity is not how long you want between refills. It is what the water weighs.

What a camper van water system is made of

Every plumbed van in the country runs the same eight parts in the same order. A fill point on the outside, a fresh tank, a 12 volt pump, an accumulator to stop the pump hunting, a filter, a water heater or a bypass around one, the taps, and a drain that empties into a grey tank. The difference between a $2,000 system and an $8,000 system is size, materials and where each part sits. It is not what is in it.

The fill point is the part buyers meet first and think about last. A gravity fill hatch cut into the body side means a hose from any spigot and a full tank in two minutes. No hatch means lifting jugs through the side door and pouring them into a tank under the bed, which is fine for a weekend van and gets old fast on a long trip. Settle it before the walls go on, because cutting the body afterwards is a shop visit rather than an afternoon.

Pressure comes from the pump rather than from height, which is what makes a van tap behave like a house tap. The pump pulls from the tank, holds the lines at working pressure and shuts off when a switch inside it senses the pressure has come back up. Everything downstream of that switch is ordinary plumbing built small, in a vehicle that vibrates.

How much water you actually need

The EPA puts the average American family above 300 gallons of water a day at home. A van runs on 1 to 4 gallons per person per day, and most owners who have done a season settle near 2. That one figure decides tank size, and it is worth arriving at honestly rather than guessing.

Do the sum in the order that actually decides things. Gallons per person per day, times people, times days between fills. Two people at 2 gallons each who want a week between refills need 28 gallons, which rounds up to a 30 gallon tank. The same two people filling every third day need 12 gallons, and a 20 gallon tank is already generous.

One thing pushes that number up and it is not the galley. Dishes, teeth, coffee and a kettle barely move it. Showering aboard can double the whole system, which is why a van with a wet bath is specified as a different water system rather than as the same one with a shower head added.

Two other things move it and both get forgotten. A dog drinks, and a dog that swims gets rinsed. And where you park is half the answer: on a campground with a spigot at the pitch, a 20 gallon tank behaves like a 60 gallon one, because you are refilling every day without noticing.

The same decision again, with the weight column attached. Days assume 2 gallons per person per day, which is the middle of the band and close to what most owners actually use.

Water is payload, and it is the heaviest thing you add

Water weighs 8.34 pounds a gallon, which follows from the 62.4 pounds per cubic foot USGS publishes for water at its densest. A full 36 gallon tank is 300 pounds. Fresh and grey together on a van with a shower aboard can be 500 before anything else is loaded.

Set that against what the van gives you. Mercedes publishes 3,450 to 3,814 pounds of payload on the 170 inch high roof 2500, which is the most common camper conversion platform in the country. The conversion itself takes most of it: cabinetry, insulation, a battery bank, a heater, the tanks and their brackets. Two adults, their clothes and a week of food come after that. 300 pounds of water is not a rounding error against that total, and it is the largest single line you get to choose.

The chassis has an answer if you need one. Mercedes publishes 4,269 pounds on the 3500 at the same wheelbase and roof, and 6,382 pounds on the 4500, which is why heavy four-season builds with big tanks go on the heavier chassis instead of arguing with the arithmetic. Off Highway Van attacks it from the other end, building in aerospace aluminium rather than timber at $165,000 to $245,000 to take several hundred pounds out of the conversion itself.

The order matters more than any individual number. Payload first, then the systems, then the tank that fits in what is left. Choosing 60 gallons and discovering the payload afterwards is how vans end up over their gross weight with an owner who has no idea.

Grey water is the tank that fills first

Every gallon that comes out of the tap has to go somewhere, and in a van that somewhere is a tank you carry until you find a legal place to empty it. A shop that fits 30 gallons of fresh and 12 gallons of grey has built a van that runs out of grey on day three with the fresh tank still half full, and you will find that out in a car park somewhere.

Size grey against the fresh tank rather than against whatever space was left over. A van with no shower can get away with roughly half, because a good share of the fresh tank leaves as coffee, cooking and drinking rather than down the drain. A van with a shower aboard wants grey capacity close to parity with fresh.

There are two ways to hold it. A chassis-mounted tank under the floor, commonly 11 to 28 gallons depending on the van and what it has to fit around, emptied at a dump station through a valve and a hose. Or a jug in the cabinet under the sink, usually 5 gallons, carried to a drain and poured out. The jug is not a compromise. It is simpler, it never freezes, it costs nothing, and it makes you notice how much water you use, which is the cheapest water saving in the van.

Where grey water is allowed to go is a rule that changes at every state line and with every land manager, so it is the one part of this system worth checking locally rather than reading about generally. Dump stations at campgrounds, truck stops and a good many municipal facilities take it for a few dollars. Pouring it on the ground is permitted in some places, prohibited in others, and always a poor idea within sight of the next person's camp.

The pump, the pressure and the pipe

Sizing the pump

A 3 gallon per minute 12 volt pump is enough for any camper van, and a bigger one only empties the tank faster. Flow is the specification most often oversold in this category, because the number reads like performance and behaves like a fuel burn.

Two things matter more than flow. A variable speed pump ramps up and down rather than hammering on and off, which is the difference between a van you can sleep in and one where somebody washing their hands at 6am wakes everybody. And an accumulator in the line after the pump holds a cushion of pressure, so a short draw at the tap does not start the motor at all.

Put the pump on its own switch by the door and use it. A pressurised system that lets go while you are out hiking empties the whole tank into the van. A switched-off one loses a cupful. It is a $6 switch and it is the best value in a van water system.

PEX A or PEX B

PEX A and PEX B are the same material made two different ways, and the difference shows up in the fittings rather than in the pipe. PEX A expands and shrinks back, so the fitting goes inside the pipe and the bore stays full. It also recovers from a freeze better than PEX B does, which matters in a vehicle that will spend nights below freezing whether you planned to or not. PEX B is stiffer, crimps with cheaper tools, and uses fittings that narrow the bore slightly at every joint.

For a van, either works. PEX A costs more in tools and less in fittings, and shops building for winter tend to specify it. What matters far more than the letter is that the runs are short, supported and reachable, because a pipe stapled behind a glued-down panel is a pipe you cannot fix.

Where the leaks actually happen

Not in the pipe. Leaks in van water systems happen at fittings tightened once in a warm shop and then driven 10,000 miles over washboard, at the tank fitting where a full tank swings on a bracket sized for an empty one, and at the pump inlet where the vibration is worst. Every one of those is a fitting rather than a material.

The fix is boring and it is cheap at build time. Flexible hose either side of the pump, brackets sized for the full weight rather than the dry weight, a sealed floor or a drip tray under the tank, and an access panel to every joint. Ask a builder to show you the access rather than the finish, because the finish is what they photograph and the access is what you will need at 11pm in Utah.

Hot water, and what it costs in power

Hot water is where a water system stops being plumbing and turns into an energy decision. Three routes, and they are nowhere near each other on cost or on draw.

• Electric, either a 4 to 6 gallon tank or an inline element. The simplest to fit and the heaviest draw in the van outside air conditioning.
• On demand propane. Cheap to buy and cheap to run, and it needs a vented enclosure, a propane locker and a hole in the body.
• Hydronic, taking heat off a diesel heater that is already fitted. The neat answer, the expensive one, and the only one that heats the van and the water from the same tank of fuel.

Electric is the route that catches people, because it is the easiest to install and the hardest to live with. A tank element pulls a large fraction of everything a van's battery bank can deliver, and sizing the bank around a heating element is a different exercise from sizing it for a fridge, a fan and some lights.

Hydronic makes sense in one situation, and it is a common one. If the van is already getting a diesel air heater for winter, taking hot water off the same loop costs less than a separate appliance and adds nothing to the electrical load, so a heater specified for the whole van has to be settled before the water heater is chosen rather than after.

And the honest fourth option is none of them. A kettle heats enough water for dishes and a strip wash, weighs nothing, costs nothing and never leaks. A large share of vans under $50,000 have no water heater at all, and most of those owners are not the ones writing in to complain.

Where the tanks go

Three places, and the choice sets everything downstream of it. Inside, under a bed or a bench, is where most fresh tanks live. The water sits at cabin temperature, which means it does not freeze while the heater is running, and every fitting stays reachable. The cost is floor space, and the fact that 250 pounds now sits wherever you put it, high or low, forward or aft.

Underslung, bolted to the chassis rails, buys back that whole footprint and puts the weight low, which is the best place for weight to be. It also puts the tank out in the weather and in the path of whatever the road throws up, so on a van built to leave the pavement an underslung tank wants a skid plate and a route that clears the exhaust.

Over the wheel well is the third option and the most underrated. A shallow moulded tank uses the dead space above the arch, which is space no cabinet ever uses well. It costs nothing in floor area and it keeps the weight over the axle, which is exactly where you want it.

Wherever the tank goes, keep it low and near the centre of the van if the layout allows. 250 pounds sitting behind the rear axle changes how the van behaves in crosswind and on gravel, and it is the sort of thing nobody notices until there is a bike rack back there as well.

Filtration, and whether you can drink it

Filtration in a van does two jobs, and most systems only do one of them. A sediment filter before the pump stops grit from a campground spigot chewing up the pump. A carbon filter after it makes the water taste like water rather than like a plastic tank in an Arizona summer. Neither one turns unsafe water into safe water, and no filter sold for a van pretends otherwise if you read the box.

What decides potability is what went into the tank. Municipal spigots, campground taps and RV fill points in the United States are supplied with treated drinking water, and a tank filled from those and kept clean holds drinking water. Filling from a stream, a lake or an unknown well is a different question, and the answer to it is treatment rather than filtration.

The EPA's emergency disinfection guidance is the plain version: a rolling boil for 1 minute, 3 minutes above 5,000 feet, or 8 drops of 6 percent unscented household bleach per gallon. That is the standard to hold unknown water to, and it is worth knowing before the trip where you need it rather than during it.

Sanitise the tank itself twice a year, and again after the van has sat. A tank left full, warm and closed for a month grows a film on the inside, and nothing downstream of it fixes the taste. Ask a builder for a fill port you can get a brush and a hose into, because a tank you cannot clean is a tank you will end up replacing.

Winterising a van water system

Water is the only system in a van that destroys itself when it freezes, and it does not take a polar night to manage it. A tank inside the cabin is fine while the heater runs. The pipe run to the shower, the pump, the outdoor tap and an underslung tank are the parts that reach freezing first, usually at 4am with the heater turned down to save fuel.

Shops pick one of two strategies. Keep everything inside the envelope, which means tanks and every run within the insulated shell rather than under it, and accept what that costs in floor space. Or accept the freeze and design the van to drain in ten minutes: low point drains, a bypass around the water heater, and a habit of emptying it when the forecast says so.

The first is what a four-season shop sells. Vanna Adventure Vans builds four-season rigs at $120,000 to $240,000 in West Fargo, North Dakota, which is a shop that lives through the winters it specifies for, and Rossmönster runs $130,000 to $250,000 out of Longmont, Colorado building for winter capability rather than for a photograph. Both start by keeping the tanks inside the insulated envelope rather than heating a pipe that sits outside it.

Heated tank pads and heat tape exist and they work. They are also a battery load on the coldest night of the year, which is the night the battery is already working hardest and the solar array is contributing nothing. Specify them as a backup to a drainable system, never as the plan.

What a shop's water system includes at each price band

Water is the line item most often described and least often specified. A quote that says water system tells you almost nothing, and the distance between two shops' versions of that phrase is $5,000.

Under $40,000 it means a tank, a pump, a sink and a drain into a jug, with no hot water in most cases. Glampervan runs $30,000 to $65,000 building on one chassis only, the 136 inch ProMaster high roof, so the tank and its brackets are a solved component rather than a fresh problem on every van. Vertical Vans is $35,000 to $95,000 on mainly ProMaster with an 8 to 10 week turnaround, and Custom Coach Creations takes full conversions from $18,695.

Between $65,000 and $140,000 the system becomes two plumbed tanks, filtration, hot water and usually an outdoor shower on the rear door. Ready.Set.Van publishes fixed packages at $65,000 to $95,000. Papago Vans runs $85,000 to $140,000 out of Phoenix, where the design brief starts at 110 degrees and the water spec moves with it. DM Vans publishes $97,000 to $105,000 and is RVIA certified, which means the build is inspected against the industry's electrical, propane and egress standards rather than self-attested.

Above $150,000 the water system gets engineered rather than fitted. Off Highway Van at $165,000 to $245,000 builds in aluminium to buy back the payload the tanks spend. Brooklyn Campervans starts at $92,000 and delivers the Elevate v4 at $292,000 with an Infinity Shower that recirculates and UV-sterilizes a single gallon of water rather than draining a tank, which is the one genuinely different answer in this category. It turns the shower from a tank problem into a power problem, and a power problem is the easier of the two to solve.

Comparing what each shop puts inside that phrase is the only useful way to read the numbers, and the 10 builders on the national ranking split roughly three ways on it: fixed packages with a published water spec, custom shops that specify per van, and shops that will fit a system into a van somebody else started.

That third group is worth knowing about, because plumbing is one of the few things in a van that retrofits cleanly. Blue Ridge Adventure Vehicles takes work from $5,000, which at that end of its range means systems rather than a whole van. Contravans will add electrical, storage or plumbing to a van already under way, with modular work turned around in 4 to 6 days. Neither of those is a full build, and neither is priced like one.

What to settle before you sign

Water gets specified late in most builds and it should be settled early, because three of its decisions are structural. Where the tank sits, whether there is a gravity fill hatch cut into the body, and whether the runs are inside the insulated shell. All three are cut into the van, and none of them changes later without furniture coming back out.

The paperwork has an opinion as well. A permanently installed water supply with a sink is on the list most states want to see before they will retitle a van as a recreational vehicle, and an RV title is what moves the loan from 5 years to 15. A jug and a bowl do not count for that, whatever else they do well.

A shop that answers all six on a phone call has built enough water systems to have opinions about them. A shop that treats water as a detail to sort out nearer the time has just told you when you will be sorting it out.