When a sudden rainstorm forces you to shut down a job site, the crew’s morale drops as fast as the fuel gauge—yet a reliable under‑tonneau tank can keep power flowing and deadlines intact. You’ll uncover seven models that balance capacity, durability, and compliance, each tailored to different truck setups. The right choice could mean the difference between a stalled engine and a smooth, on‑time finish, so let’s explore what each option brings to the table.
| uws Combo Transfer Tank 75 Gal Black |
| Industry‑First | Capacity (gal): 75 gal | Fuel Type: Diesel (non‑flammable liquids) | Material: Steel‑aluminum combo (14‑gauge steel) | VIEW LATEST PRICE | Read Our Analysis |
| RDS MFG INC 71791 Rectangular Transfer Liquid Tank – 91 Gallon Capacity |
| Heavy‑Duty | Capacity (gal): 91 gal | Fuel Type: Diesel (aux gasoline gasoline via pump) | Material: Steel (unspecified) | VIEW LATEST PRICE | Read Our Analysis |
| DEE ZEE DZ92556NB Transfer Tank |
| Aluminum Elite | Capacity (gal): 40 gal | Fuel Type: Diesel (non‑flammable liquids) | Material: Brite‑Tread aluminum | VIEW LATEST PRICE | Read Our Analysis |
| RDS 8 GPM Pump Combo with 60‑Gal Tank & Toolbox |
| Pump‑Combo Pro | Capacity (gal): 60 gal | Fuel Type: Diesel (non‑flammable liquids) | Material: Aluminum + stainless steel | VIEW LATEST PRICE | Read Our Analysis |
| Dee Zee DZ92556N Transfer Tank |
| Compact Classic | Capacity (gal): 39 gal | Fuel Type: Diesel (non‑flammable liquids) | Material: Brite‑Tread aluminum | VIEW LATEST PRICE | Read Our Analysis |
| RDS MFG INC – 72117 Transfer Tank 70Gal |
| Versatile Performer | Capacity (gal): 70 gal | Fuel Type: Diesel (auxiliary gasoline possible) | Material: Steel (unspecified) | VIEW LATEST PRICE | Read Our Analysis |
| AM-TANK Portable 40‑gal Diesel Tank with Pump & Filters |
| Portable Power | Capacity (gal): 40 gal | Fuel Type: Diesel | Material: Aluminum (powder‑coat) | VIEW LATEST PRICE | Read Our Analysis |
More Details on Our Top Picks
uws Combo Transfer Tank 75 Gal Black
Looking for a lightweight yet rugged fuel solution that won’t eat up your truck bed? The UWS Combo Transfer Tank 75 Gal Black gives you 75 gallons in a sleek, machined black finish while staying 189.6 lb—far lighter than full‑steel tanks. Its 14‑gauge steel shell, 100 % pressure‑tested, handles diesel and other non‑flammable liquids safely. The patented rigid‑core foam‑filled lid prevents binding, and the lockable, vented cap with reinforced collar keeps pressure in check. You’ll also appreciate the built‑in toolbox, extra storage, and drain plug for quick emptying—all without sacrificing bed space.
- Capacity (gal):75 gal
- Fuel Type:Diesel (non‑flammable liquids)
- Material:Steel‑aluminum combo (14‑gauge steel)
- Dimensions (in):52 × 29 × 25
- Drain Plug Size:Not specified (built‑in drain plug)
- Lockable Cap / Vent:Lockable vented cap with reinforced collar
- Additional Feature:Rigid Core foam lid
- Additional Feature:Built‑in toolbox storage
- Additional Feature:Commercial‑grade vented cap
RDS MFG INC 71791 Rectangular Transfer Liquid Tank – 91 Gallon Capacity
The RDS MFG INC 71791 rectangular transfer tank is the ideal pick for truck owners who need a high‑capacity, space‑saving diesel reservoir that fits snugly under a tonneau cover. It holds 91 gallons, measures 57 × 29 × 19 inches, and weighs just 1 lb, so it slides into short‑bed trucks without sacrificing cargo space. Gravity‑feeds diesel from its bottom, and you can add the optional Diesel Install Kit to connect directly to the OEM fuel line. The tank ships empty—no pickup tube, pump, hose, or nozzle—so you pair it with your preferred pump. RDS offers a 30‑day Amazon return and a manufacturer warranty through customer service.
- Capacity (gal):91 gal
- Fuel Type:Diesel (aux gasoline gasoline via pump)
- Material:Steel (unspecified)
- Dimensions (in):57 × 29 × 19
- Drain Plug Size:Not specified (tank only)
- Lockable Cap / Vent:Not specified (no cap detail)
- Additional Feature:Vehicle‑specific fit
- Additional Feature:Gravity‑feed bottom outlet
- Additional Feature:Optional Diesel Install Kit
DEE ZEE DZ92556NB Transfer Tank
If you need a rugged, lightweight tank that fits under a tonneau cover without adding bulk, the Dee Zee DZ92556NB delivers with its 40‑gallon, Brite‑Tread aluminum construction and a radius‑curve design that eliminates weld pressure points. We 60 lb, 59 × 22 × 10 in unit holds diesel safely, thanks to three stability baffles, a lockable cap, and a 3/8 in drain plug. Mounting tabs secure it in your truck bed, while the venting coupler prevents pressure buildup. The black powder‑coat finish resists rust, and the tank meets Title 49 US Federal Registry standards for non‑commercial use. You’ll enjoy a 30‑day Amazon return and optional manufacturer warranty.
- Capacity (gal):40 gal
- Fuel Type:Diesel (non‑flammable liquids)
- Material:Brite‑Tread aluminum
- Dimensions (in):59 × 22 × 10
- Drain Plug Size:3/8 in
- Lockable Cap / Vent:Lockable cap
- Additional Feature:Radius‑curve weld design
- Additional Feature:3 stability baffles
- Additional Feature:Mounting tabs for bed
RDS 8 GPM Pump Combo with 60‑Gal Tank & Toolbox
RDS’s 8 GPM pump combo, paired with a rugged 60‑gal aluminum tank and built‑in toolbox, is perfect for truck owners who need a reliable, high‑capacity fuel‑transfer solution while keeping their bed clear. You’ll appreciate the fully welded seams and heavy‑duty aluminum brackets that secure the unit under any tonneau cover. The spin collar lets you install the pump quickly, and the stainless‑steel pump handles diesel or nonflammable liquids without leaks. At 110 lb and 55 × 20 × 23 in, it fits snugly, while the integrated toolbox stores tools for on‑the‑spot repairs. Amazon offers a 30‑day return, and RDS backs it with a customer‑service warranty.
- Capacity (gal):60 gal
- Fuel Type:Diesel (non‑flammable liquids)
- Material:Aluminum + stainless steel
- Dimensions (in):55 × 20 × 23
- Drain Plug Size:Not specified (drain plug included)
- Lockable Cap / Vent:Lockable vented cap (integrated)
- Additional Feature:Integrated storage toolbox
- Additional Feature:Spin collar pump install
- Additional Feature:Aluminum‑stainless steel construction
Dee Zee DZ92556N Transfer Tank
Looking for a rugged, high‑capacity tank that fits neatly under a tonneau cover without compromising strength? The Dee Zee DZ92556N delivers 39 gallons in a 59 × 22 × 10 in frame, built from heavy‑gauge Brite‑Tread aluminum with a radius‑curve design that erases weld pressure points. You’ll appreciate three stability baffles, a lockable cap, a 3/8″ drainage plug, venting coupler, and mounting tabs for secure bed placement. We weighs 60 lb. It’s for non‑flammable liquids only, private‑use only, and doesn’t meet Title 49 regulations. Available since December 24 2017, Amazon offers a 30‑day return guarantee and a manufacturer warranty via the provided link.
- Capacity (gal):39 gal
- Fuel Type:Diesel (non‑flammable liquids)
- Material:Brite‑Tread aluminum
- Dimensions (in):59 × 22 × 10
- Drain Plug Size:3/8 in
- Lockable Cap / Vent:Lockable cap
- Additional Feature:Radius‑curve weld elimination
- Additional Feature:3 stability baffles
- Additional Feature:Truck‑bed mounting tabs
RDS MFG INC – 72117 Transfer Tank 70Gal
The 70‑gallon RDS MFG INC 72117 Transfer Tank is the ideal pick for truck owners who need a high‑capacity, dual‑fuel solution that fits neatly under a tonneau cover. We you 98 lb unit measures 48 × 13.59 × 26 in, giving you ample space for diesel and gasoline. Diesel flows by gravity from the tank’s bottom, while gasoline is delivered through an electric top‑pump. An optional Diesel Install Kit lets you connect directly to the OEM fuel line. Since its 2010 debut, it’s earned solid Amazon rankings and a 30‑day guarantee. You’ll enjoy reliable fueling without sacrificing cargo room.
- Capacity (gal):70 gal
- Fuel Type:Diesel (auxiliary gasoline possible)
- Material:Steel (unspecified)
- Dimensions (in):48 × 13.59 × 26
- Drain Plug Size:Not specified (drain plug included)
- Lockable Cap / Vent:Not specified (cap not detailed)
- Additional Feature:Dual diesel/gasoline capability
- Additional Feature:Optional Diesel Install Kit
- Additional Feature:Gravity‑feed bottom outlet
AM-TANK Portable 40‑gal Diesel Tank with Pump & Filters
If you need a diesel reserve that slides neatly under your tonneau cover and still offers full‑tank capacity, the AM‑TANK 40‑gal portable tank is the ideal solution. It measures 38.66 × 22.91 × 18.11 in, weighs 49.9 lb, and fits snugly beneath most covers. A 12 V pump delivers 12 GPM, runs on 300 W, and includes a 20‑ft cord with ON/OFF switch. The built‑in 30 µm particulate and water filter protects your engine, while a 13‑ft hose with auto‑nozzle speeds refueling. Forklift pockets, securing grooves, and a lockable lid keep it safe during transport and storage.
- Capacity (gal):40 gal
- Fuel Type:Diesel
- Material:Aluminum (powder‑coat)
- Dimensions (in):38.66 × 22.91 × 18.11
- Drain Plug Size:2 in filling plug (drain not listed)
- Lockable Cap / Vent:Protective cover lid with lockable latches
- Additional Feature:12 V diesel pump
- Additional Feature:Particulate & water filter
- Additional Feature:Forklift pockets for lifting
Factors to Consider When Choosing an Under Tonneau Cover Transfer Tank
When you pick a tank, start by matching its capacity and dimensions to your truck’s under‑tonneau space. Next, check the material’s durability, the weight for portability, and whether the pump fits your existing setup. Finally, make sure the lid locks securely to keep the fuel safe.
Capacity and Dimensions
Because space under a tonneau cover is limited, you must match a tank’s length, width, and height to the usable area while leaving room for hinges and latches. First, measure the interior width of your bed—most range from 48 in to 60 in—and guarantee the tank stays within that span to avoid hitting side rails or wheel wells. Next, check the tank’s height; low‑profile covers usually require under 12 in to keep the center of gravity low and the cover seal intact. Finally, balance capacity with volume: a 40‑gal tank consumes about 0.5 ft³, while a 75‑gal unit needs roughly 1 ft³, directly affecting the space left for tools or cargo. Verify that the tank’s overall dimensions allow the cover to open and close smoothly, without binding or excessive pressure on seals.
Material and Durability
Matching the tank’s size to your bed’s dimensions is only half the battle; the material you pick determines how well it will hold up under real‑world conditions. Aluminum tanks shave up to 30 % off your load and resist corrosion, making them ideal for frequent trips and salty roads. If you need raw strength, steel offers superior impact resistance, though a 75‑gal steel tank can tip past 150 lb. Look for Brite‑Tread aluminum with a powder‑coat finish for a non‑rusting surface that stays sturdy in wet environments. Rigid‑core foam‑filled lids protect both aluminum and steel tanks from pressure‑induced deformation, extending service life. Heavy‑gauge (14‑gauge) steel meets pressure‑testing standards, ensuring durability for regular diesel transfers. Choose the material that balances weight, corrosion resistance, and impact strength for your specific workload.
Weight and Portability
If you keep the tank’s weight low, you’ll ease suspension stress, boost handling, and improve fuel economy. Aim for a tank under 100 lb so a single person can lift it without a hoist; this keeps manual handling quick and safe. Choose aluminum or a steel‑aluminum hybrid—these materials shave up to 30 % off the weight of a comparable full‑steel tank while keeping capacity intact. Look for integrated handles, forklift pockets, or built‑in toolbox grips; they let you remove and reposition the tank without extra tools. A compact footprint that fits snugly within your tonneau cover dimensions prevents cargo interference and preserves accessory clearance. Balancing lightweight construction with ergonomic features guarantees the tank stays portable and vehicle‑friendly.
Pump Compatibility Options
When selecting a pump for your under‑tonneau cover transfer tank, prioritize matching its flow rate to the tank’s capacity so fill and empty times stay practical— a 12 GPM pump will clear a 40‑gal tank in roughly three to four minutes, whereas a 4 GPM unit stretches that to about ten minutes. Next, verify voltage and amperage; a 12 V, 22 A pump draws ~264 W, which fits most truck batteries. Make sure the inlet/outlet size—3/8 in or 1/2 in—matches the tank’s built‑in ports to eliminate leaky adapters. Check the duty cycle and IP rating; a 30‑minute on/off cycle and IP55 protection let you run the pump in dusty or wet conditions. Finally, confirm the pump is rated for your fuel type, whether diesel, gasoline, or both, and any auxiliary fueling needs.
Lockable Lid Security
A lockable lid with a reinforced collar or steel‑core construction is essential for keeping your tank secure while you drive, because it resists tampering and accidental opening. Choose a lid whose lock uses a hardened steel has or a high‑strength polymer, so cutting or picking becomes practically impossible. Verify the sealing gasket matches your fuel—diesel, gasoline, or bio‑fuel—and can stay pressure‑tight despite temperature swings. Look for a secondary safety latch or lock‑out feature; it gives you redundancy if the primary lock fails. Finally, make sure the key or combination system meets industry standards for corrosion resistance and outdoor durability, ensuring reliable operation rain rain, snow, or dusty roads. These factors together protect your fuel and give you peace of mind.
Drain Plug Accessibility
Because you’ll need to empty the tank quickly and safely, prioritize a drain plug that’s both easily reachable and compatible with standard tools. Choose a common size—like 3/8 in—so you can grab a wrench or socket from your toolbox without hunting for specialty parts. Position the plug at the tank’s lowest point; this guarantees the liquid drains completely, leaving no residual fuel that could cause corrosion or fire hazards. Opt for a lockable cap or a vented design that stays sealed during transport, preventing accidental opening that could spill diesel. Select stainless‑steel construction to resist rust and water damage over years of use. Finally, verify that you can access the plug from the truck bed without removing the tonneau cover, saving time and effort on every service.
Compliance and Regulations
A drain plug that’s easy to reach won’t help if the tank itself violates any legal requirements. You must verify that the tank meets Title 49 U.S. Federal Transportation regulations for its intended use—whether you’re hauling for personal or commercial purposes. Check that the tank is approved for your fuel type—diesel or non‑flammable liquids—and never use gasoline unless the manufacturer explicitly permits it. Guarantee the cap is vented, lockable, and that the construction has passed pressure testing to prevent leaks. Confirm the tank’s capacity and build comply with state and local hazardous‑material transport limits for road vehicles. Finally, review the warranty and documentation to make sure compliance certifications are current and provided by the maker.