The Propur Big is essential for an emergency preparedness plan for you and your family. It is economical, convenient and easy to use. The system requires no electricity to provide reliable water filtration just about anywhere whether at home, office, vacation, camping or college dorms! Works with just about any water source including tap, lake, river, stream, pond and rain water. Ideal for emergency or daily use. Each container is made from one piece of high quality polished or brushed(optional finish) stainless steel for lasting durability and attractive appearance. The system comes equipped with two ProOne G2.0 7 All-In-One contaminants & fluoride filter elements and can be expanded up to three filters.