MSR MIOX Purifier

This purifier weighs 99g; no pumping required; water tastes good; effective against viruses; allows water to be treated away from collection point. But requires 43g of salt for 200 litres, 2 x lithium batteries and 50 test strips (replacement kit of salt and test strips is £15); takes 30 minutes to treat water; complicated to use; high running costs.

Verdict: Buy it if you want a lightweight system that is very effective, and the service life and running costs are not an issue.