Hi Katie,
The Steripen is actually one of the lightest water sterilisation products on the market taking into account the total capacity of water the steripen can deal with.
For some background information on the effectiveness;
http://www.hydro-photon.com/testing.htmlThe Steripen system is superior to the Katadyn Micropur tablets for longer term use.
Advantages.......
The steripen is not effected by cold water unlike the Micropur tablets (a function of the time taken for the micropur tablets to take effect).
The steripen does not rely on chemicals additions. Long term use of residual chemicals based on chlorine dioxide, iodine etc is undesirable.
The steripen will sterilise 100-150 litres of water on a single set of 4 AA NiMh cells.
The steripen is very fast in treating water compared to all other water purification systems.
The steripen is simple and easy to operate.
The steripen can deal with water borne viruses. (most water filtering systems cannot deal with viruses)
Disadvantages........
The Steripen is an electronic battery powered optical device and therefore is not as robust as other water sterilisation methods in the field.
It runs on Batteries.
The water to be sterilised must be reasonably clear, therefore prefiltering of dirty water is required. i.e. something like a lightweight Millbank Bag maybe required. Micropur tablets are also not recommended with dirty water. Pre filtering would be useful with the micropur tablets aswell.
It cannot deal with chemical contamination.. but then again most water sterilisation systems cannot either including the firm favourite called the rolling boil.
For a good long term solution for water purification and sterilisation a combination of a steripen and Katadyn Pocket Microfilter would be useful.
Katadyn Micropur tablets are excellent in PSKs for short term emergencies where longer term solutions are not available.