Dunk the "dirty" hydration vessel into your water source.
Use a cup or bowl to fill the bag to maximum capacity.
Attach the filtration unit and hose to your dirty bag if it's not already attached.
Then secure the other end of the filtration unit to the "clean" bag.
Most filters, like the one pictured, have a "clean" side and a "dirty" side that should be attached to corresponding bags.
Attach the filter to your "clean" bag.
Find a tree or bush to hang the dirty bag and allow "gravity" to work its magic by forcing the water down and through the filter into the "clean" bag.
After the filtration is complete and the "clean" bag is full, you can transfer the drinking water to a number of other hydration units.