No pumping is required! Just fill and hang WakiWaki 6L water filter bag and let gravity do the work. Our gravity emergency water purification systems make sure you will always have access to enough reliable sources of pure drinking water any time anywhere, especially in an emergency. Equipped with a 0.1-micron hollow fiber ultrafiltration membrane, this gravity camping water filter reduces 99.99999% of escherichia coli, tested by SGS-CSTC Standards Technical Services Co., Ltd.Ningbo Branch (Test Report NBF21-004693-01, Date: 02 Jun 2021), filters up to 5,000 liters outdoors water. Unique detachable and backwash design ensures a long life span of water filter straw, with no need for an extra syringe. As an ideal emergency water filter, WakiWaki gravity-fed water purification system is lightweight and easy to use, suitable for camping, hiking, climbing, travel and survival.