Potable Aqua | Chlorine Dioxide Tablets | 2018 | $0.45 | 0.5g
I carry a pair of chlorine dioxide tablets as a back-up method of water purification should my primary filtration method fail. One individually-wrapped tablet will treat 1 liter of water in four hours and is effective against bacteria (giardia), cysts (cryptosporidium), and even viruses. All you have to do is open up one of the little squares, drop the tablet into a container of water, and wait. Oh, and the water tastes just fine.
Note that a Sawyer Micro Squeeze, one of the lightest membrane filters on the market, weighs about 65g wet and costs $28.99. For the same price you could purchase 64 chlorine dioxide tablets (weighing 32g total) and be able to filter 64 liters of water, or 16-21 days worth. If you’re a person who does mostly shorter trips then bringing 4-5g of tablets instead of a filter would allow for some decent weight savings as well as reducing water stop time to a bare minimum. This assumes that you carry multiple water containers and can always have a standby that’s being treated.
Granted, the total cost of ownership of the Sawyer is much cheaper given that it can filter 100,000 gallons of water over its lifetime, but spending $30 per year to eliminate the weight and hassle of non-chemical filtration might be an attractive trade-off for some.