Right out of the box, the operation of this small, light-weight kit was obvious. Fill the bag marked "dirty" with your raw water, connect the hoses and filter with the flow indicator arrow pointing toward your "clean" bottle, and let gravity do the rest. I don't know why, but I was expecting a slow drip like an IV bag. Instead, water gushed from the hose into the "clean" bottle. To maintain that level of performance, the system is easily back-flushed for maintenance by placing your clean vessel up and the dirty bag down.