Safe drinking water on the trail comes from removing or killing what you cannot see, and filters and tablets do that job in very different ways.

A squeeze or pump filter physically strains out sediment, protozoa such as Giardia and Cryptosporidium, and bacteria, giving you drinkable water in under a minute.

Purification tablets using chlorine dioxide kill bacteria, viruses and protozoa, including Cryptosporidium after a four-hour wait, but they do not remove grit, chemicals or bad taste.

The smart system for most hikers is a lightweight filter as the main tool, with a strip of tablets tucked in a repair kit as a backup if the filter clogs or breaks.