Treating pigs via the drinking water involves the same principles, a daily intake of the active principle based on mg/kg of live weight. In practice however, it is better to consider this by the active medicine required per day per tonne of live weight of pig. For example, if the water soluble preparation consists of 100% pure active medicine, (in other words no carrier added to it), then for most antibiotics, this level would range from approximately 15-25g/tonne of live weight per day. If, however, the powder contains only 50% of active principle (the other 50% would be a carrier, usually a sugar or citric acid base), then the dose would be 30-50g/tonne of live weight or twice the amount. The initial calculation, however, would be based upon mg/kg live weight. As a guide pigs drink 100 litres of water per tonne of liveweight per day. For example a treatment level of 10mg/kg of active medicine and using a 50% powder, 20g/tonne would be required. In practice if the administration is by nipple drinkers the level is increased by up to 20% to allow for wastage.