What is the best portable method of purifying water to prevent infectious disease?

Abstract

There isn't a single best method, but there are 5 that adequately purify water according to Environmental Protection Agency (EPA) standards. These include 1) boiling for 1 minute if below 2000 m (6562 feet) and 3 minutes if above, 2) chlorine dioxide tablets, 3) MIOX purifier, 4) ultraviolet light (SteriPEN ), and 5) portable filtration with a absolute pore size <1 micrometer combined with halogenation or charcoal filtration (strength of recommendation [SOR ]: C, based on expert opinion and microbiological testing). Halogenation alone (ie, chlorine and iodine) is not effective against Cryptosporidium (SOR : C, based on microbiological testing).