3/4'' UNISEAL Flexible Tank Adapter (bulkhead)

I used these 3/4" Uniseals to attach 3/4" PVC pipe to 2 gallon and 5 gallon buckets to run my poultry cups to various places in the run and coop. Found them at bulk reef supply with free shipping for a little over $2/ring.

You do need a hole saw in order to make the hole in your bucket. If you have an electric drill but no hole saw bit (need 1 and 1/4 inch hole, I think), you can find a bit that will make the perfect hole for $7-10.

Once the hole saw has done its job (done in seconds), all you have to do is push the Uniseal through the hole, then put your 3/4" PVC pipe through the Uniseal hole.
No leaks, no caulk, no tape- NO leaks. I chose to put mine in the side of the buckets- should work for bottom of bucket too.

The only thing that was a little hard was putting the PVC through the Uniseal hole, but that's a good thing, and that's why you don't have to use any caulk or tape.

I used two Uniseals for each bucket- one that feeds the watering cups, and the other acts as a drain for the bucket with a PVC ball valve so I never, ever have to pick up and invert anything.
If you want to remove the bucket for cleaning without moving PVC pipes with poultry cups/nipple system (picture was taken before cups were installed in PVC pipe), just pull the 3/4" PVC out of the Uniseal (after it's empty, of course), clean, push it back through the hole, refill.

Not so much as a drop lost through the Uniseal, but I imagine the hole saw is key to this result.