It really doesn't matter if both are even hooked to it, so long as one
is. This isn't a flow through situation. You could have a T in the
line and run one leg of it to the tank and all would be good.

On Sep 28, 12:05 am, wrote:
When installing or replacing the well pressure tank, does the supply
line always have to hook up to the left side (facing the tank) of the
brass "T", or can it be hooked up to the right side. It appears to me
that hooking the supply line up the the left side oe the "T" and the
demand side up to the right side is a standard. But does it really
matter if they are swapped?