This document discusses vaccination through drinking water. It emphasizes protecting the vaccine virus particles in the water and water lines. Factors that can affect the outcome of water vaccination include the age of birds, their water consumption, the water withdrawal time before vaccination, the timing of vaccination, the exposure time to vaccinated water, and ensuring an even dosage through evaluating vaccination with a blue dye. Protecting the vaccine from factors like heat, light, chlorine and organic matter is important for successful vaccination.