The water jugs had the little white vent fittings that you push into or pull up from the hole. I removed those and used a 3/8" drill bit to enlarge the holes, then put a couple of wraps of Teflon tape around the nylon fitting and screwed it into the jug. Turning tank upside down there was no leakage (there was very slight drippage without the tape). Of course these won't have that much pressure on them when right-side up. Then pushed hose onto barb.

The water jugs had the little white vent fittings that you push into or pull up from the hole. I removed those and used a 3/8" drill bit to enlarge the holes, then put a couple of wraps of Teflon tape around the nylon fitting and screwed it into the jug. Turning tank upside down there was no leakage (there was very slight drippage without the tape). Of course these won't have that much pressure on them when right-side up. Then pushed hose onto barb.