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 high quality premium 304 stainless steel for lasting durability, corrosion and oxidation resistance and attractive appearance.