NPT on PVC or CPVC fittings where the outside of the fitting is threaded to facilitate connection with a female pipe threaded end (FPT). NPT is National Pipe Thread – the US standard for tapered threads.

A 5-1/2” hole must be drilled with a bi-metal style hole saw for each adapter. The hole must be drilled at the small cone-shaped marks that are molded into the ends of the inlet and outlet. The 3/8” location pin on the flange of the adapter must be cut off and filed flush with the flange. The gasket of the adapter goes on the inside of the tank and can be tightened with large adjustable type pliers or pipe wrenches.
B. Drill a 5” hole in the ends of the tank at the cone-shaped inlet/outlet location marks and install a 4” gasket. It is your responsibility to contact the local code official and install the plumbing tee lengths and weights per the requirements.