After looking at the bulkhead fitting you have, it may or may not be
made to the diameter of the standard size of PVC pipe.

Hi Roy, Bill - Don't all bulkhead fittings come threaded so they will make a
watertight seal with whatever type of fitting you choose (hose barb, elbow
etc) I have never seen the type you guys are talking about
On second thought, why wouldn't you use one that is threaded for
connections instead of relying on cement or silicone to make them
watertight? - a 1" bulkhead fitting is only ~$7 Can
JMO Gale :~)