40 Litre Underfloor Fresh Water Tank (Backfill) for Ford Transit Custom (2012–2022)

This 40-litre underfloor fresh water tank has been purpose-designed for the 2012–2022 Ford Transit Custom L1 and L2 models. Ideal for campervan and motorhome conversions, it provides a reliable and discreet fresh water supply solution mounted beneath the vehicle.

Manufactured from durable, corrosion-resistant polyethylene, the tank features a matt black finish for a clean, long-lasting underfloor installation. Its hygienic, algae-resistant construction ensures safe water storage and consistent performance in long-term builds.

A large threaded top-mounted access hatch allows installation of pumps, internal accessories or sensors, and provides easy access for periodic cleaning.

Fitting Instructions

This tank installs widthways (driver side to passenger side) within the underfloor cavity of the Ford Transit Custom. The mounting space is positioned between the chassis members and is safely distanced from the exhaust system.

The service hatch must face upwards, with the tank orientated to clear brake lines and factory underfloor components on the L1/L2 models.

Additional Benefits of the Backfill System

This backfill system has been successfully fitted to many conversions and is fully proven in practical use. Its universal faceplate design allows the filler point to be mounted anywhere suitable inside the vehicle—with no exterior bodywork cutout required. This makes it ideal for both new conversions and retrofits.

Key Advantages

  Can feed jet wash systems (if your jet wash can self-prime).

Works as a dual-purpose outlet, allowing the tank to be emptied without a separate drain tap—ideal for winterising.

Simplifies installation by combining several functions into one fitting.

Maintains a clean exterior look thanks to the no-cutout design

What’s Included

1 × 40L Water Tank
(Approx. L: 850mm, W: 370mm, D: 150mm)

 1 × 1/2" Elbow for attaching the breather pipe

2 × 1/2" Straight connectors for the blue feed pipe

1 × 1m long 1/2" Breather Pipe

1 × 2m long 1/2" Blue Flexible Water Pipe

1 × Backfill Point with Isolator Valve

 4 × Jubilee Clips for securing pipework

 1 × Universal Tank/Strap Fitting Kit & Fixings

Important Information

Water level senders compatible with Victron Energy & SRNE systems are available. (Here)

Tanks may contain traces of water on arrival—this is normal due to leak-testing.

Ensure the tank is fully cleaned before first use.

Specifications

Capacity: 40 litres

Dimensions: 850mm (L) × 370mm (W) × 150mm (H)

Dry Weight: approx. 3.5kg