The Platypus GravityWorks 4.0 Liter High-Capacity Water Filtration System is ideal for basecamps, group and family camping, outdoor activities, and emergency preparedness. It does not require pumps, batteries, moving parts, or chemicals, ensuring access to clean water from contaminated sources, in situations ranging from adventure to survival. The replaceable hollow-fiber microfilter cartridge filters up to 1,500 gallons of water, and meets all EPA and NSF guidelines for removal of 99.9999% of bacteria and 99.9% of protozoa, including Giardia, Cryptosporidium, E. coli, Salmonella, and Cholera. The water filtration system is easy to use almost anywhere. Simply scoop water from a lake, river, stream, or other contaminated water source into the 4.0-liter dirty water reservoir, and suspend above the 4.0-liter clean water reservoir. Water flows through the walls of the bundled fibers at rate of 1.75 liters/minute, leaving impurities behind, and filling the 4.0-liter clean water reservoir in just 2.5 minutes. It’s also easy to maintain in the field, backflushing in just four seconds to clean and restore performance. The Platypus GravityWorks 4.0 Liter High-Capacity Water Filtration System includes a 4-liter dirty water reservoir, 4-liter clean water reservoir, hollow-fiber microfilter, hoses, shutoff clamp, and storage sack. The complete kit is compact, packing down to the size of a one-liter water bottle, and weighs just 11.5 ounces. Made in the USA.