Returned and installed bypass shut off for whole house carbon filter to attempt to repair the dripping union after the O-ring replacement didn’t work. Informed customer that the connecting piece at the top of the filter didn’t appear to unthread and is likely built into the whole unit. Customer informed me that the filter was only installed three years ago and Pentair has a warranty for five years. Customer will reach out to Pentair for a replacement filter. Quoted the labor to install a new filter and soak properly. Customer will call when Pentair has sent the unit.