Looking for a grey water tank to compliment your freshwater tank? Check out our 15 Gallon Promaster Undermount Tank! The undermount tank fits snugly under the passenger side of your Promaster’s framed undercarriage; the perfect solution for your off-grid water requirements.

Key Features & Benefits:

• Space Saving - A unique way to make efficient use of that awkward wheel well area and shape.
• Perfectly Shaped - Not only do these tanks mold to the shape of your wheel well but the top and outside are also squared off to account for further building. Last we checked, it’s easier to build a square box than a round one.
• Build Options - These tanks are interchangeable between both wheel wells; you can fit this tank over whichever wheel well works best for your build. Need more water? Place one on either side of your van for mega-volume!
• Distributes Weight - Adds weight over your rear axle to help increase traction if you get in a sticky spot. No more slips and skids, not to mention unwanted wheel wear, thanks to the perfect weight distribution of these tanks.
• Sound Proofing - When it comes to road noise, these tanks step it up with added noise reduction around your wheel well.
• BPA-Free and Food Grade Approved - Feel safe knowing these tanks are food grade CSA approved! Wash the dishes, have a shower, fill the dog bowl, and stay hydrated, while exploring in your van!
• Fittings Kit Add-On Available - Save yourself the headache and multiple trips to the plumbing store when you bundle this tank with our Freshwater Fittings Kit!
• Strapping Kit Add-On Available - Weather-resistant strapping crafted from heavy-duty 1/8" thick, 1 1/2" wide stainless-steel. Simple and secure! 
• Water Level Sender & Gauge Kit Add-On Available - This water tank has a fitting specifically designed for use with the KUS S5U Water Level Sender!
• Compatible - Pairs well with our 15 Gallon Promaster Undermount Water Tank. 

Dimensions & Specifications:

Designed for the Ram Promaster 136", 159" & 159" extended wheelbases.
Compatible with the Mercedes Sprinter & Ford Transit, all wheelbases.

Tank can be placed on either the PASSENGER SIDE or DRIVER SIDE of the van.
Fits around the wheel well with or without flooring installed in the van.

Tanks are made from linear low-density polyethylene.
Food grade CSA approved and BPA free - safe for freshwater use!

32 US Gallons / 121.1 Litres

45” 16.5” 19” (Length x Width x Height)

1 x 1 ½” drill-out membrane port (on top at one end)
2 x 1 ¼" drill-out membrane ports (on top at either end)
2 x 1 ¼" drill-out membrane ports (one on each end)
2 x ¾" ports (one on each end)
4 x ½” ports (two on each end)
1 x 1 ½” drill-out membrane port (on side of the tank - you can ignore this!)
2 x 1 ¼" drill-out membrane ports (on side of the tank - you can ignore these!)

The larger 1 ½”  and 1 ¼" ports are "membrane ports", which require drill-out for use.
The membrane eliminates the need to plug the ports if you don't use them.

All ports are NPT female-threaded.

Fresh Water Fittings Kit Add-On:

• 1x 1 ¼" PVC 90
• 2x ¾" PVC 90
• 1x ¾" PVC Ball Valve
• 1x ¾" Nipple - 6" long
• 1x ¾" Nipple - 4" long
• 1x ¾" Nipple - 1 ½" long
• 1x ½" Poly Adaptor
• 2x ½" Poly Elbows
• 1x ¾" PVC Plug
• 2x ½" PVC Plugs
• 2x #20 Hose Clamps
• 2x #8 Hose Clamps
• 1x Roll of Teflon Tape
• 1x Fill Port
• 5ft Fill Hose
• 5ft ⅝" ID Vinyl Hose

Stainless-Steel Strapping Kit Add-On:

• Specifically designed for your Promaster Wheel Well Water Tank
• Kit includes 2x Heavy-Duty Stainless-Steel Straps & Stainless-Steel Mounting Hardware

More Information: 

Wheel Well & Undermount Water Tank FAQ Sheet

Full Details of the Fresh Water Fittings Kit Add-On
Select this add-on with your tank purchase and save $$ vs buying separately!

Full Details of the Stainless-Steel Strapping Kit Add-On
Select this add-on with your tank purchase and save $$ vs buying separately!

Check out our Promaster Wheel Well Water Tank (22 Gallon)

Check out our Promaster Undermount Water Tank (15 Gallon)

Install Instructions:

Freshwater Fittings Kit Install Instruction