Vetafarm's Wormout Gel is a good broad spectrum wormer to add to water. It contains praziquantel and oxfendazole. I have used it, and it needs a lot of stirring to mix well. I used hot water at first, stirred, and then added the rest cold. It treats all chicken worms when given over 2 days, including capillary, tapeworm, roundworms, cecal, and gapeworm. Foys Pigeon Supply online is one of a couple that sell it. Casportpony has reported on someone using Valbazen in the water for a day, but I cannot find the amount. I have tried Valbazen in water, but it seems to settle.