Our Promaster undermount water tanks have been selling like hot cakes - you didn't think we'd forgotten about the Sprinters did you? These undermount tanks save valuable space inside your van by creating grey water storage underneath your van.

Alternatively, these tanks are food grade CSA certified, and BPA free, so you can also use them for extra freshwater storage. Bundle this tank with our Freshwater Fittings Kit, and save yourself a trip (or multiple trips!) to the plumbing store. 

Need something smaller? We also have a 10 Gallon Sprinter Undermount Water Tank.

Looking for the complete set-up? Pair your undermount tank with our 29 Gallon Sprinter Wheel Well Water Tank to complete your off-grid water management system. Have a dually? no problem! Check out our 32 Gallon Sprinter Dually Wheel Well Water Tank! Spend more time at the campsite and less time searching for water fill-up stations!

Key Features & Benefits: 

• Save Space - Mount underneath your van chassis for extra storage room inside your van - driver side only.
• Perfect Fit - Designed to fit perfectly under the Sprinter van, simply position the tank and attach with strapping, no need to make modifications. Check out our easy-to-install Stainless- Steel Strapping Kit.
• Durable Design - This tank is tough; rest assured knowing your tank will hold up to exposure and the elements.
• Multi-Purpose - Use this undermount tank for grey water storage, or bundle it with our Freshwater Fittings Kit and turn this tank into a freshwater reservoir; option to mount in your van's interior, as a freshwater tank. 
• BPA-Free and Food Grade Approved - These tanks are CSA approved and food grade certified for safe drinking water.
• Fittings Kit Add-On Available - Save yourself the headache and multiple trips to the plumbing store when you bundle this tank with our Grey Water Fittings Kit or Fresh Water Fittings Kit!

• Compatible - This tank pairs well with our 29 Gallon Sprinter Wheel Well Water Tank.

Dimensions & Specifications:

Designed for the Mercedes Sprinter, all wheelbases.
Compatible as an interior water tank, for any van. 

The tank can only be mounted on the DRIVER SIDE of your Sprinter van, however, your drain hose can be routed to your passenger side if needed. The end of the tank with the 4 x fittings (1 x 1 ¼", 1 x ¾", and 2 x ½") usually faces the rear of van, but the tank can be faced in either direction.

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

17 US Gallons / 64.3 Litres

41" x 11.5" x 8.5" (Length x Width x Height)

1 x 1 ¼"  drill-out membrane port (on top)
1 x 1 ¼" drill-out membrane port (on ONE end)
1 x ¾" port (on ONE end)
2 x ½" ports (on ONE end)

The larger 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.

Grey 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 Adaptors
• 1x ½" Poly Elbow
• 1x ½" PVC Plug
• 2x #20 Hose Clamps
• 1x #8 Hose Clamps
• 1x Roll of Teflon Tape
• 5ft Fill Hose
• 2ft ⅝" ID Vinyl Hose

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
• 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 the undercarriage of your Sprinter van
• 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 Grey Water Fittings Kit Add-On
Select this add-on with your tank purchase and save $20 vs buying separately!

Full Details of the Fresh Water Fittings Kit Add-On
Select this add-on with your tank purchase and save $20 vs buying separately!

Full Details of the Stainless-Steel Strapping Kit Add-On
Select this add-on with your tank purchase and save $30 vs buying separately!

Check out our Sprinter Undermount Water Tank (10 Gallon)

Check out our Sprinter Wheel Well Water Tank (29 Gallon)

Check out our Sprinter Dually Wheel Well Water Tank (32 Gallon)