Guest 3/8 Union Tee

The John Guest 3/8" Union Tee from Reliance Worldwide Corporation provides three equal 3/8" push-fit ports in one compact body, letting you split a water line into two directions. It is a versatile branching fitting for reverse osmosis, filtration, and multi-outlet water treatment plumbing, and because every port stays at full size, it preserves flow on each leg of the split.

With all three ports at 3/8", this tee carries full flow on every branch, making it ideal for splitting a main run into two equal lines or adding a second point of use without stepping down in size. The push-fit design lets you tap an existing line without cutting in a metal branch or soldering, which keeps the job fast and the junction clean.

Key Features

• Connection: Tube x Tube x Tube, all three ports 3/8"
• Equal union tee maintains full line size on every leg
• Polypropylene construction resists corrosion and scale
• Push-in collets grip each tube with no tools needed
• Fully demountable for flexible reconfiguration
• Reusable across multiple installs and repairs

Installation is straightforward. Cut each of the three tubes square and free of burrs, then push them fully into their ports until they seat past the collets. The internal O-rings seal each connection automatically, and a light tug confirms the grip on every leg. The corrosion-resistant polypropylene body stands up to continuous contact with treated water without scaling or rusting, so the tee performs reliably for the long haul. To rework the layout later, depress the collet of any port and withdraw the tube undamaged, then reconnect as needed. This demountable design makes it easy to add or remove a branch as household needs change over time. For clean, dependable, full-flow three-way branching in residential water treatment systems, this John Guest union tee is a reliable, reusable choice.

As part of the broader John Guest family, this equal tee works seamlessly with the unions, elbows, valves, and plugs that share the same collet system, letting you design and later rework a full distribution layout from interchangeable parts. Maintaining full 3/8" size on every leg means neither branch is starved, which is important when both outlets must deliver consistent flow to their respective points of use.