Our Promaster undermount water tanks have been selling like hot cakes - you didn't think we'd forgotten about the Transits 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 Transit Undermount Water Tank.

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

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 Transit van, simply position the tank and attach with strapping, no need to make modifications. Check out our easy-to-install Aluminum 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!
• Strapping Kit Add-On Available - Weather-resistant strapping crafted from heavy-duty 1/8" thick, 1 1/2" wide aluminum. 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 - This tank pairs well with our 29 Gallon Transit Wheel Well Water Tank, or with our 32G Transit Dually Wheel Well Water Tank!

Dimensions & Specifications:

Designed for the Ford Transit, all wheelbases.
Compatible as an interior water tank, for any van. 

The tank can only be mounted on the DRIVER SIDE of your Transit 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 ½” drill-out membrane port (on top)
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 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.

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

Aluminum Strapping Kit Add-On:

• Specifically designed for the undercarriage of your Transit van
• Kit includes 2x Heavy-Duty Aluminum Straps & Aluminum 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 $$ vs buying separately!

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 Aluminum Strapping Kit Add-On
Select this add-on with your tank purchase and save $$ vs buying separately!

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

Check out our Transit Undermount Water Tank (10 Gallon)

Install Instructions:

Freshwater Fittings Kit Install Instruction
Grey Water Fittings Kit Install Instruction
Strapping Kit Install Instructions for Transit 17 Gallon Water Tank (Driver Side)

Designed for the Ford Transit, all wheelbases.
Compatible as an interior water tank, for any van.
The tank can only be mounted on the DRIVER SIDE of your Transit 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.

Is this tank compatible with a water level sensor?
Yes! Check out our KUS Water Level Sensors and Gauges.

Can you recommend a water tank heating pad?
We recommend these heating pads from Amazon: https://www.amazon.ca/Trailer-Holding-Automatic-Thermostat-Control/dp/B01MT9EUG9

Are the 10 Gallon and 17 Gallon Transit Undermount Water Tanks compatible with my Ford Transit factory running boards?
Yes, the 10 Gallon and 17 Gallon Transit Undermount Water Tanks are compatible with OEM factory running boards / steps.

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