When Josh needed to haul diesel fuel to his construction sites, he found that choosing the wrong transfer tank cost him valuable time and money. You’ll find that selecting the right under-tonneau transfer tank isn’t just about capacity – it’s about matching your specific needs with features like pump efficiency, material durability, and safety compliance. Before you invest in your next fuel transport solution, let’s explore the seven most reliable options available in 2025.
RDS MFG INC 71791 Rectangular Transfer Liquid Tank – 91 Gallon Capacity
For truck owners seeking versatile fuel transport, the RDS MFG INC 71791 offers a dual-purpose 91-gallon tank that supports both gas and diesel refueling. You’ll find gas siphoning capability from the top using an electric pump, while diesel fuel gravity feeds from the bottom.
At 57 x 29 x 19 inches and weighing 77.6 pounds, this tank fits select short beds, though you’ll need to measure your truck first. While it’s sold without accessories, an optional diesel install kit helps connect to your OEM fuel tank. With a 4.7-star rating, customers praise its durability, though some mention weld quality concerns.
Best For: Truck owners who need a versatile auxiliary fuel tank for both gasoline and diesel fuel transport, particularly those with compatible short-bed trucks seeking dual-fuel capability.
Pros:
- Dual-purpose design allows both gas siphoning from top and diesel gravity feed from bottom
- Large 91-gallon capacity provides substantial fuel storage
- High customer satisfaction with 4.7/5 star rating from 34 reviews
Cons:
- Sold as tank only – requires separate purchase of pump, hose, and other accessories
- Some reported issues with weld quality and flange durability
- Specific fit requirements necessitate careful measurement before purchase
DEE ZEE DZ92556NB Transfer Tank
Truck owners seeking a versatile diesel transfer tank will appreciate the DEE ZEE DZ92556NB’s practical design and 40-gallon capacity. This tank’s .125 Brite-Tread aluminum construction with black powder coating resists rust and corrosion, while its radius curve design minimizes weld pressure points.
You’ll find three stability baffles for enhanced durability, along with mounting tabs for secure truck bed installation. The tank includes a lockable cap, 3/8 drainage plug, and venting coupler. While it’s rated well at 4.2 stars, remember it’s only for non-flammable liquids and isn’t approved for commercial use or auxiliary fuel systems.
Best For: Truck owners who need a durable, non-commercial diesel transfer tank for occasional transport of non-flammable liquids.
Pros:
- Rust-resistant aluminum construction with protective black powder coating
- Three stability baffles and radius curve design for enhanced durability
- Includes security features like a lockable cap and secure mounting tabs
Cons:
- Not approved for commercial use or auxiliary fuel systems
- Cannot be used for gasoline or flammable liquids
- Doesn’t meet U.S. Federal Registry requirements for transportation (Title 49)
Portable Gasoline Fuel Tank with 12V Electric Pump (40 Gallon)
Mobile fleet operators and contractors will appreciate this 40-gallon portable fuel tank’s versatility and convenience. The LAPPPLSP tank’s durable polyethylene construction resists corrosion while remaining lightweight at 70 pounds.
The 12V electric pump delivers an impressive flow rate of up to 10 GPM, making quick work of fuel transfers. You’ll find the four detachable wheels, two with brakes, make positioning effortless. The tank’s compatibility with gasoline, diesel, and kerosene means you can service various vehicles in your fleet. Its built-in filtration system guarantees clean fuel delivery, while the 33-foot maximum head provides excellent reach for most applications.
Best For: Fleet managers, contractors, and maintenance teams needing a portable fuel solution for multiple vehicles or equipment on job sites.
Pros:
- High-capacity 40-gallon tank with fast 10 GPM pump flow rate
- Versatile compatibility with different fuel types (gasoline, diesel, kerosene)
- Mobile design with four detachable wheels and built-in brakes for secure positioning
Cons:
- Relatively low Amazon sales rank suggests limited market presence or customer feedback
- Heavy when full (approximately 370 pounds with fuel)
- Short 30-day warranty period compared to industry standards
AM-TANK 58 Diesel Portable Tank with 12V Pump
Designed to fit under tonneau covers, the AM-TANK 58 Diesel Portable Tank offers contractors and fleet managers a 58-gallon capacity solution for efficient fuel transport. The tank’s 12V pump delivers 12 GPM through a 13ft flexible hose with an automatic nozzle.
You’ll appreciate the integrated particulate and water separator filter that guarantees clean fuel delivery, while the fuel level indicator helps monitor your diesel inventory. The tank’s forklift pockets and handles make moving it a breeze, whether full or empty. Securing grooves work with ratchet straps for safe transport. Just remember to maintain the filter regularly to prevent flow rate issues and keep your pump running smoothly.
Best For: Contractors and fleet managers who need a portable diesel fuel solution that fits under truck tonneau covers and offers reliable fuel transfer capabilities.
Pros:
- High capacity 58-gallon tank with integrated filtering system and water separator
- Easy mobility with forklift pockets, handles, and securing grooves for transport
- Complete fuel transfer system with 13ft hose, automatic nozzle, and fuel level indicator
Cons:
- Pump performance can be inconsistent and flow rate may be slower than expected
- Mixed customer service experiences and warranty support
- Regular filter maintenance required to prevent clogging and maintain optimal performance
Dee Zee DZ91752 (39 gallon) Narrow Rectangle Transfer Tank – Aluminum
The Dee Zee DZ91752 aluminum transfer tank offers a slender yet robust solution for drivers who need extra liquid storage without sacrificing bed space. With its 39-gallon capacity and narrow 9-inch width, you’ll maintain valuable truck bed real estate while gaining substantial liquid transport capability.
Built from non-rusting 0.125 Brite-Tread aluminum, this tank features three stability baffles, a lockable cap, and a convenient drainage plug. While it’s not certified for fuel transport, you’ll find it perfect for non-flammable liquids. Installation might require minor modifications, but the tank’s durability and functionality make it worth considering, despite occasional reports of shipping-related issues.
Best For: Truck owners needing extra liquid storage capacity while maintaining bed space, particularly those transporting non-flammable liquids like water or diesel exhaust fluid.
Pros:
- Narrow design preserves valuable truck bed space while providing substantial 39-gallon capacity
- Durable aluminum construction with three stability baffles prevents corrosion and ensures structural integrity
- Includes security features like a lockable cap and convenient drainage system
Cons:
- Installation may require modifications and additional equipment not included with purchase
- Not certified for fuel transport under Title 49 regulations
- Some quality control issues reported with shipping damage and potential cap leakage
AM-TANK 40 Portable Diesel Tank with 12V Pump
Fitting neatly under a truck’s tonneau cover, AM-TANK’s 40-gallon diesel transfer tank offers contractors and fleet operators a secure fuel solution that won’t compromise cargo space. At 38.66 x 22.91 x 18.11 inches and weighing just under 50 pounds, this tank integrates essential features like forklift pockets and securing grooves.
You’ll appreciate the robust 12V pump system, which delivers 12 GPM through a 13-foot flexible hose with an auto-nozzle. The setup includes a particulate filter, water separator, and fuel level indicator. While some users report minor issues with the fill cap and cold-weather hose stiffness, the tank’s 4.3-star rating reflects its solid construction and reliable performance.
Best For: Fleet operators, contractors, and truck owners needing a reliable diesel transfer solution that fits under a tonneau cover while maintaining cargo space.
Pros:
- Efficient 12V pump system with 12 GPM flow rate and integrated filtration
- Compact design with practical features like forklift pockets and securing grooves
- Comprehensive setup including 13ft hose, auto-nozzle, and fuel level indicator
Cons:
- Fill cap may have leaking issues and ventilation concerns
- Hose becomes stiff in cold weather conditions
- Installation instructions lack model-specific details and clarity
RDS Fuel Transfer Tank with Pump (60-Gal Capacity)
Many truck owners seeking a versatile storage solution will appreciate RDS’s combination fuel transfer tank and toolbox, which packs 60 gallons of capacity into a sleek aluminum housing.
While the unit’s fully welded seams and 8 GPM pump offer solid functionality, you’ll want to inspect yours carefully upon delivery. Users report shipping damage and durability concerns with the latches and thin diamond plate construction. Some owners have needed to modify vents and re-thread output plugs for peak performance. At $1,300-$1,500, you might consider BETTER BUILT’s competing models, which customers rate higher for quality and reliability.
Best For: Truck owners who need a combination fuel transfer tank and toolbox solution with moderate capacity and are willing to accept potential quality trade-offs for functionality.
Pros:
- Combines fuel tank and toolbox functionality in one unit
- 60-gallon capacity with included 8 GPM pump
- Aluminum construction with fully welded seams
Cons:
- Quality control issues and frequent shipping damage reported
- Thin diamond plate construction and weak latches
- May require modifications and repairs for optimal performance
Factors to Consider When Choosing an Under Tonneau Cover Transfer Tank
When you’re selecting an under-tonneau transfer tank for your truck, you’ll need to evaluate several critical features to guarantee the best fit for your needs. You should assess the tank’s size and capacity in relation to your bed space, verify the material quality and construction durability, and check that the pump system meets your flow rate requirements. The mounting system, installation clearances, and built-in safety features like pressure relief valves and anti-siphon devices will also impact your final choice.
Tank Size and Capacity
Selecting the right tank size and capacity stands as a critical decision when purchasing an under-tonneau transfer tank. You’ll need to carefully measure your truck’s bed dimensions to guarantee proper fit while maintaining access to other cargo space. Transfer tanks typically range from 39 to 91 gallons, giving you various options to match your needs.
Remember that a full tank’s weight will greatly impact your truck’s performance and handling. For example, if you’re hauling diesel, you might need a different capacity than if you’re transporting gasoline. Look for tanks specifically designed for your truck model, as they’ll offer optimized dimensions for better balance under your tonneau cover. This proper fit prevents unwanted movement during transport and guarantees maximum efficiency in your available space.
Material and Construction Quality
Beyond tank size considerations, the material and build quality of your transfer tank directly impact its longevity and performance. You’ll find most tanks are made from either aluminum or polyethylene, with aluminum being the superior choice for durability and corrosion resistance.
Look for tanks featuring fully welded seams and radius curves, as these design elements prevent leaks and reduce stress points. Premium aluminum options, like .125 Brite-Tread, offer an ideal balance of lightweight construction and durability. Don’t overlook built-in stability baffles – they’re vital for controlling fuel movement during transport.
When evaluating construction quality, pay attention to user reviews about weld integrity and packaging protection. A well-built tank should resist dents and maintain its structural integrity throughout years of use.
Pump System Specifications
A crucial element of any transfer tank setup, the pump system requires careful consideration of multiple technical specifications. You’ll want to look for pumps that deliver flow rates around 10 GPM to guarantee efficient fuel transfer operations. Pay attention to the duty cycle – most 12V pumps operate for 30 minutes before needing a cooling period.
Check the pump’s suction height capability, which should reach up to 6.6 feet vertically for versatile installation options. The construction material must be durable and compatible with different fuel types. Don’t forget to verify the inlet and outlet connections, typically NPT 3/4 inch, to confirm they’ll work with your existing hoses and fittings. These specifications will directly impact your transfer tank’s performance and reliability.
Mounting and Installation Requirements
Proper mounting and installation of your under-tonneau transfer tank demands careful attention to several key requirements. You’ll need to verify that your chosen tank model aligns with your truck’s specific configuration, as different vehicles may require custom modifications or shimming for a secure fit.
Check that your tank includes integrated mounting points and ascertain there’s adequate clearance beneath your tonneau cover for the fill spout and pump system. You’ll want to distribute weight evenly and use compatible ratchet straps that match your truck’s load capacity. Keep in mind that installation might require basic tools and electrical work for pump wiring. Before finalizing your purchase, confirm that the tank’s design works with your truck bed’s features and that you have all necessary adapters for fuel lines.
Safety Features Available
Safety features in modern under-tonneau transfer tanks offer critical protection for both your fuel and vehicle investment. You’ll want to prioritize tanks equipped with lockable caps to prevent theft and unauthorized access during transport. Look for models that include drainage plugs and venting couplers, as they’re essential for safe liquid transfer and pressure management.
Don’t overlook the importance of stability baffles, which keep your fuel from sloshing around and potentially causing dangerous shifts in weight distribution. Make sure your chosen tank complies with Title 49 regulations for non-flammable liquid transport. For additional protection, you’ll benefit from a particulate and water separator filter system that keeps contaminants from damaging your equipment’s fuel system.
Price Vs Build Quality
When selecting an under-tonneau transfer tank, you’ll need to weigh the relationship between cost and construction quality carefully. While budget-friendly options might seem attractive initially, they often come with risks of shipping damage, poor welds, and questionable components that can lead to problems down the road.
Higher-priced tanks typically feature superior materials like Brite-Tread aluminum, which resists corrosion and provides lasting durability. You’ll find these premium models offer reinforced seams and better overall construction. Though they require a bigger upfront investment, they’re usually backed by solid warranties and deliver better long-term value.
Consider your tank an investment in your truck’s functionality. The correlation between price and build quality often reflects in customer satisfaction ratings, with well-built tanks earning consistently higher reviews for their reliability and performance.
Maintenance Access Points
Beyond build quality, the accessibility of maintenance points can make or break your experience with an under-tonneau transfer tank. You’ll want strategically placed access points that let you clean, inspect, and repair without removing the entire tank from your truck.
Look for tanks with removable components and external mounting for pumps and filters – this makes routine maintenance remarkably easier. Built-in gauges and indicators can reduce your need to physically access the tank’s interior while monitoring fuel levels. When evaluating your options, consider whether the tank’s maintenance points are compatible with standard tools you already own.
The best under-tonneau tanks feature thoughtfully designed access points that save you time and frustration during regular upkeep, ultimately extending your tank’s service life.