Although Katadyn MP1 Tablets are probably the safest of all the chemical treatments available because of the different types of nasties it can deal with there are better solutions for purifying water. The Steripen Adventurer with Solar Charger Case is I think the neatest solution available when used in conjunction with a Millbank bag. The Millbank Bank is used to firstly filter the water to remove any particulate matter. The Steripen system then uses UV light to destroy any nasties DNA, which effectively destroying the ability to reproduce. The Steripen system is also probably the quickest way to purify water. I know of nothing that will produce a litre of purified water so quickly in the field. The Steripen system will not cope with water contaminated with chemicals, although again no other system currently available claims that it can except possibly a distillation system of water purification. Highly recommended. The only other problem is that the Steripen system is to just to large for a PSK although it probably also one of the lightest and smallest non chemical tablet systems available.