How to Install a Transit Undercarriage Water Tank: Driver-Side

Last updated: September 15, 2026

Overview

Install a Ford Transit 20-gallon driver-side undermount water tank (TR-UC-20) in ~2 hours using 3/8-16 rivnuts, 3/8" bolts, and provided brackets. The tank mounts under the driver side of your Transit, using fuel tank mounting bolts as front anchors and rivnuts in the side wall as rear anchors. Locate fuel tank bolts, mark side wall mounting points, drill, install rivnuts, hang brackets, mount the tank, and tighten with Loctite. Your Transit is ready for plumbing.

Before You Start

  • Vehicle: Ford Transit

  • Tank: GoCode TR-UC-20

  • Mounting location: Driver or passenger side / undercarriage

  • Estimated installation time: ~2 hours

Tools & Materials

  • 1/2" socket and ratchet

  • 9/16" socket and ratchet

  • Tape measure

  • Marker

  • Step bit, or drill bits up to 17/32"

  • Drill

  • Rivnut tool (pneumatic gun or hand tool)

  • Shop vac or broom for shavings

  • Primer

  • Brackets, 3/8" bolts, rivnuts (3/8-16), and Loctite (included with the tank)

Installation Instructions

  1. Locate the fuel tank mounting bolts

The three rearmost fuel tank mounting bolts serve as the front mounting points for the tank brackets.

  1. Mark the side wall
    Hold a bracket between the frame rail and the side wall, aligned with the first fuel tank bolt and perpendicular to the rail. Mark the side wall at the bracket's mounting point. Using that first mark as your control point, measure and mark at roughly 13 3/4" and 33 1/4".

  2. Drill the mounting points
    Drill the side wall marks to 17/32". A step bit works well here, or use a series of increasingly larger bits.

  3. Clean up the shavings
    Take a minute to sweep out the metal shavings before you keep going. Rolling around on them is no fun.

  4. Prime and set the riv-nuts
    Prime the exposed metal at each hole, then install the rivnuts. We use a pneumatic rivnut gun, but any rivnut tool will do the job.

  5. Hang the front bracket
    Remove the first fuel tank bolt. Loosely mount the provided bracket using a 3/8" bolt and the fuel tank bolt you just removed. Slide the tank into place through the bracket.

  6. Mount the tank
    Lift the rear of the tank into place and mount the remaining brackets using the fuel tank bolts. That holds the tank while you start the 3/8" bolts into the side wall rivnuts. Use Loctite, and don't tighten anything until every bolt has been started. Tighten the 3/8" bolts with a 9/16" socket and the fuel tank bolts with a 1/2" socket.

  7. Eat the gummy bears

    That's it. The tank is installed and ready to plumb. Crack open the gummy bears packed with the tank. You earned 'em.

Installation Video

Follow this video for a step-by-step guide to installing an undercarriage tank on the driver's side of a Ford Transit.

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