SPECIALLY FORMULATED TO HELP CLEAN OUT CAMELBAK RESERVOIRS THESE NEW TABLETS WORK IN JUST A FEW MINUTES TO REDUCE TASTE & ODOUR. SIMPLY ADD 1 TABLET TO 1 LITRE OF WATER IN ANY SIZE OF RESERVOIR ALLOW TO SOAK FOR 5 MINUTES RINSE OUT & YOURE READY TO GO.ACTIVE INGREDIENT: CHLORINE DIOXIDE.