The DOGNESS Pet Water Fountain is a healthy and hygienic drinking fountain that is perfect for pets of all sizes. The water comes from a 1 liter bottle that is filled by an automatic pump. The water is then filtered through a 3-piece filter system that includes a carbon layer, a copper layer, and a stainless steel mesh. The water is then stored in a large reservoir before being pumped into the bowl. The water is safe to drink and is free of chlorine, lead, or other chemicals.