I would keep him away from waterfowl. Waterfowl are very resistant to diseases. They won't show symptoms, but they can still carry diseases that peafowl can get. If they were free range and interacting with waterfowl that's one thing. It would be best to keep peafowl on their own if you're going to pen them up. @KsKingBee is NPIP Certified and could give you some information. Usually your state agriculture website will let you know what it takes to become NPIP Certified too.
I worm them using Safeguard 1 cc per 4 lbs. An adult peacock weighs about 12 lbs and a hen weighs about 10 lbs. 3 cc of Safeguard, directly in the mouth or in/or a treat such as bread or tomatoes. DO NOT put it in their water. Safeguard is not water soluble, and it will not get to the birds in the proper amount. Worm them for 5 days, and then take a 10 day break, and then worm for another 5 days. The 10 days is the most crucial part. The reason why is most wormers don't kill eggs, so you have to wait for them to hatch. So you have to kill the new generation before they can reproduce. That's why it's a 10 day wait.
Twice a year. When the ground freezes and when it thaws.
Find a good avian vet to work with and have routine fecals done.
