NW Conversions 25 Gallon Dually Wheel Well Water Tank (SP-DU-25)

Shaped specifically around a dually wheel arch — 25 gallons out of space a single-wheel tank cannot use.

Dual-rear-wheel vans have a wider, taller wheel arch than a single-wheel van, and a standard wheel-well tank simply will not sit down against it. The SP-DU-25 is cut for that arch: 46" long, 20" tall, 14" deep, wrapping the well instead of fighting it.

If you are building on a 3500 dually you are almost certainly building heavy anyway — a 3500 chassis carries the 210 lb of a full tank without complaint.

Should you buy this tank, or a different one in the range?

• Buy the SP-DU-25 if you have a dual-rear-wheel van and want the most water you can get around the arch.
• Buy the SP-DU-19 if you need the slimmer 10" profile.
• Buy a standard SP-C or SP-L/R tank if your van is single-rear-wheel — the dually profile wastes space on an SRW arch.

Confirmed fitment

Specifications

These tanks are not pressure vessels. They must be vented to atmosphere — a sealed tank will balloon on a hot day and collapse inward when the pump draws it down.

What ships to you

• (1) SP-DU-25 25 gallon rotomolded tank
• Fittings, hose and mounting hardware sold separately

Installing it: what actually happens

Check the arch before you order. Dually arches vary between platforms and between model years more than people expect, and a tank cut for a Sprinter 3500 arch can sit proud on some Transit duallys. Measure the height of your arch at its peak and the length of flat floor either side of it.

Once it fits, the install is conventional: base pan, foam interface, straps high into the ribs.

• Measure your arch peak height and the flat floor either side before ordering.
• Strap into wall ribs as well as the floor — 20" tall and 237 lb full.
• Open only the ports you will use, on the bench.
• ProMaster: 3.5" of elevation required.

Questions we get asked about this part

How much weight am I adding to the van?

Water weighs roughly 8.34 lb per gallon, so 25 gallons is about 209 lb of payload once full, on top of the dry weight of the tank. Put that number in your build budget before you order rather than after — it is the most commonly forgotten figure in a van conversion.

Do I have to drill the ports myself?

On the wheel-well tanks the 1/2" NPT ports arrive open and ready to thread. The 1.5" ports are spun closed at the factory so you only open the ones your plumbing actually uses. Open them with a hole saw on the bench, before the tank goes anywhere near the van, and vacuum the shavings out. Plastic chips inside a fresh water tank are a mistake you only make once.

Does the tank need a vent?

Yes. It is designed to run unpressurized. Run a vent line from the top 1.5" port up above the maximum fill level and out through the floor or a body vent. Skip it and the tank will deform on a hot day, then pull its walls in when the pump runs.

Will it fit a single-rear-wheel Sprinter?

It will sit in one, but you will waste space: the cut-out is shaped for the taller dually arch, so on an SRW van you end up with a void under the tank. On a single-wheel van buy the SP-C or SP-L/SP-R tanks instead.

Pairs well with

• Van water tanks and plumbing — the rest of the NW Conversions range

Sold and shipped by Campervan Parts R Us, the parts counter of Noke Van Co. — a working van conversion shop in Roanoke, Virginia. If you are unsure whether this fits your van, email us the year, model and wheelbase and we will check it against a build sheet before you order.