Water is a very important nutrient, but it is also used as a carrier for drinking water vaccinations and for all kinds of in-water treatments. This means that the water quality must also be suitable for that. For (modified) live vaccines, no traces of disinfectants should be in the water during vaccination. The solubility of some antibiotics and chemotherapeutics depends on the pH of the water and can be influenced by the presence of minerals. Together with these minerals, additives can form a biofilm inside the water tubes. Large amounts of bacteria’s can bind on this biofilm. That’s the reason why the water system must always be cleaned after in- water treatments.