We all do it, but now when you find that weeks ok, months old full reservoir in your bag, you can use the Platypus Cleaning Kit to mend your misdoing. The big brush cleans out the reservoir itself, while the tiny brush scrubs out the drinking tube. Heres a tip if its super-funky: fill the whole deal with water, then add a denture tablet. Wait fifteen, then scrub and rinse approx. one billion times until the old lady smell is gone.