The bypass valve is your best friend. It lets you redirect water around the softener if you ever need to work on it. Most systems come with this as a separate piece that glues or screws onto the unit’s inlet and outlet.
Use Teflon tape on the threads to prevent leaks. Wrap it clockwise, like you’re putting a lid on a jar. Then hand-tighten everything—no gorilla grip needed, just firm and snug.