If you drink 3 litres per day it will last 3456 years! The heart of this kit is the high volume Sawyer Squeeze Filter which uses a microfibre filter with absolute micropores of 0.1 microns that lets the water through but filters out the bad stuff including bacteria, protozoa or cysts like E. Coli, Giardia, Vibrio, Cholera & Salmonella typhi. What you get out is clean safe drinking water. The Filter itself is quite simply the best filter for performance, size & weight with a total field weight of only 85g. You can use the Squeeze Filter as a straw, drinking directly from a water source, or attach it to the included Sawyer Squeeze pouch or your own water bottle. It has a high flow rate & the filter comes with a 3, 785, 412 litre guarantee. Cleaning couldn’t be simpler, you just backwash the filter with clean water using the supplied cleaning syringe to rinse out all the bad stuff & then continue to use as normal. Ways to use this system: Fill up the Squeeze bag at your water source, screw the filter directly onto the pouch & squeeze the bag to filter clean safe water into your own water container. Fill up the Squeeze bag, screw on the filter & drink directly through the pop-up cap. You can even attach the filter directly onto your own bottle as it is compatible with most screw top threads. Drink directly from source using the Squeeze Filter like a straw