Choosing the right 40 gallon water tank for your RV can improve water storage, durability, and ease of maintenance on the road. This guide covers top options designed for RVs, including fresh and gray water applications, and highlights built-in fittings, materials, and installation notes so you can compare at a glance and select the best fit for your unit.
| Product | Brand | Capacity | Notes |
|---|---|---|---|
| T-4000 One (1) RV Fresh Water 40 Gallon Tank | classAcustoms | 40 gal | Fresh or gray water; built-in fittings |
| RV Fresh & Gray Water Tank Combo Pack (40 & 46 Gal) | classAcustoms | 40 & 46 gal | NSF certified materials; multiple tanks |
| RV Fresh & Gray Water Tank Combo Pack (30 & 40 Gal) | classAcustoms | 30 & 40 gal | Non-pressurized design; dual tanks |
| T-4000-SP Spouted 40 Gallon RV Tank | classAcustoms | 40 gal | Spouted version; wired fittings |
| Chapin USA 98142 40-Gallon Water Storage Tank | Chapin International | 40 gal | Translucent; USA-made support |
Below are five highly relevant options that align with a 40 gallon RV water setup. Each entry includes a direct link to the product and practical notes on fittings, material, and usage to help you compare quickly.
T-4000 One 40 Gallon RV Water Tank
This 40 gallon Fresh or Gray Water Holding Tank from Class A Customs is suitable for RV use and is made from NSF approved materials. It supports fresh and drinking water applications and features two 1.5″ female NPT fittings plus two 0.5″ fittings, enabling flexible plumbing configurations. The design accommodates rotation to adjust height or width, with a typical thickness around 7/32″. It is designed to sit on its side and works well in tight spaces where space optimization matters.
RV Fresh & Gray Water Tank Combo Pack (40 & 46 Gal)
This combo pack includes two tanks (40 gallon and 46 gallon) built with NSF International approved MDPE resin and UV stabilization. Both tanks feature built-in fittings—two 1.5″ balloon-style female NPT and two 0.5″ fittings—designed for reliable watertight connections. The materials and construction emphasize durability for extended RV travel, with attention to venting and non-pressurized operation. The package is ideal for users seeking separate capacities for different water lines or uses.
RV Fresh & Gray Water Tank Combo Pack (30 & 40 Gal)
This non-pressurized pair provides a 30 and a 40 gallon tank, designed for fresh or gray water. Built-in fittings include two 1.5″ female NPTs and two 0.5″ fitting ports. The design emphasizes venting and gravity filling to avoid pressurized hose connections. The two-tank setup is helpful for separating water sources or for systems that need distinct storage for different uses in an RV kitchen or bath layout.
T-4000-SP Spouted 40 Gallon RV Tank
The T-4000-SP is a spouted variant of the 40 gallon Class A Customs tank. It features a spout-style fitting and three 0.5″ NPT fittings in addition to a larger diameter fitting setup. The tank maintains NSF approved materials and is designed for non-pressurized operation, emphasizing safe handling and safe water storage in RV setups. The spout configuration can simplify pouring or refilling tasks when docked or in camp settings.
Chapin USA 98142 40-Gallon Water Tank
This translucent 40-gallon utility water tank from Chapin International offers visibility of liquid levels and portability for on-the-go water storage. The tank is made in the USA with a 6-inch wide cap, a 2-inch drain, and a 3/4-inch port compatible with standard garden hoses for draining. It’s designed for utility use, with a durable polyethylene composition and nitrile seals for water contact. A practical choice for RVers needing a lightweight, easy-to-inspect tank with straightforward drainage capabilities.
Buying Guide: Key Considerations For RV 40 Gallon Tanks
Material and certification: Look for NSF/ANSI certified or approved materials to ensure safe storage of potable water. Polyethylene with UV stabilization is common for outdoor exposure and long life.
Fittings and ease of plumbing: Tanks with built-in fittings (1.5″ NPT, 0.5″ NPT) simplify installation. Check whether fittings require membranes removal and if the tank is sealed or open-ended to prevent leaks or over-tightening damage.
Ventilation vs. pressurization: Many RV tanks are non-pressurized and require venting. Direct garden hose connections to a pressurized system can cause damage or tank failure. Always follow the manufacturer’s guidance on filling methods and venting needs.
Dimensions and compatibility: Confirm the tank’s measurements and orientation flexibility (can sit on its side or be rotated). Width, height, and length matter for limited RV compartments, especially when installing multiple tanks or tanks near appliances.
Use case and capacity options: A 40-gallon tank can support fresh water or gray water storage; combo packs offer multiple capacities for differentiated systems. Consider whether you need a single tank, a paired setup, or a spouted variant for easier pouring.
In selecting a 40 gallon RV water tank, prioritize NSF-approved materials, appropriate fittings, and suitable dimensions for your specific RV layout. Whether you need a standalone 40-gallon tank or a package with multiple capacities, these options provide a range of configurations to support safe, flexible water storage while traveling.