I'm at my wits end............ I had GREAT luck with the first bucket waterer I made this summer with 3 nipples. Since then I've tried to make a different version (smaller bucket) and for the life of me I can't figure out why they leak. I drill the hole the EXACT size as recommended. Actually they are nice and tight as I put them in the pvc....... So why do they leak??? Note black arrow in picture below. It it because they are supposed to be installed in a flat surface and not a round pvc pipe? I've even tried waterproof silicone sealant and I have the same problem. What do I need to do or use to permanently seal them to the pipe? Thank you!