Water Worker G-5W and G-12W Thermal Expansion Tanks – Pre-Charged, Steel, Vertical Water Heater Expansion Tank – NSF Certified, Potable Water Safe – 2 or 4.4 Gallon Capacity (White, G-5W 3 Pack)

Ensure Long-Term Water Heater Performance with Water Worker Expansion Tanks Protect your home’s plumbing and extend the life of your water heater with the Water Worker G-5W and G-12W Thermal Expansion Tanks. Designed for use in closed, pressurized potable water systems, these tanks prevent dangerous pressure buildup caused by thermal expansion—helping to safeguard pipes, fixtures, and your water heater from stress and potential damage. Constructed with heavy-duty steel and equipped with a high-grade butyl diaphragm and polypropylene liner, the G-5W (2-gallon) and G-12W (4.4-gallon) tanks provide a durable and maintenance-free solution. The pre-pressurized internal air chamber absorbs excess water volume as it heats and expands, relieving pressure and maintaining safe system operation. Installation is fast and simple thanks to the vertical design and standard 3/4-inch male NPT connection. Whether you’re upgrading a residential water heater or replacing an existing expansion tank, Water Worker tanks are engineered to integrate seamlessly into your system.

• Protects Plumbing and Extends Water Heater Life – The Water Worker G-5W (2-gallon) and G-12W (4.4-gallon) thermal expansion tanks are designed to safely absorb excess water pressure caused by thermal expansion in closed-loop water heater systems. Prevents pressure buildup that can damage pipes, fixtures, and your water heater.
• Heavy-Duty Steel Construction with Durable Inner Liner – Built with a robust steel shell and a polypropylene liner that separates the water from the pre-charged air chamber, these expansion tanks resist corrosion, cracking, and waterlogging—ensuring long-lasting performance in residential and light commercial water systems.
• Pre-Charged and Ready for Easy Installation – Each Water Worker expansion tank is factory pre-charged for quicker, easier installation. The G-5W and G-12W models feature a vertical design and a 3/4" male NPT connection, making them compatible with most standard water heater setups. Installation is simple with basic plumbing tools.
• NSF Certified for Potable Water Systems – These tanks are NSF/ANSI 61 certified for safe use in drinking water systems, making them ideal for residential water heaters. The butyl diaphragm ensures a tight seal and helps maintain system pressure without contaminating the water supply.
• Reliable Performance – Water Worker tanks are proudly made and rigorously tested for quality and performance. Ideal for both traditional tank-style and tankless water heater systems, these thermal expansion tanks offer peace of mind with proven reliability in high-pressure environments.