Bushwalk Australia

Most people seem to have some sort of water purification system nowadays (filter, Steripen, etc), but most also take purification tablets as a backup.

My tablets have passed their use by date by about a year (hardly ever used them), and I need to get some more for an overseas trip shortly.

I wonder which tablets people are using now and what the pros and cons of each are?

The ones I carried around for years are Micropur Forte MF 1T. These have silver and sodium dicchloroisocyanurate as the active ingredients. They claim to deal with bacteria, giardia and viruses. 30 minutes to treat a litre for bacteria and viruses, 2 hours for protozoa.

One thing I wonder about tablets if whether they are safe to use in an aluminium bottle? Coudl they react with the aluminium, or even corrode it?

EDIT: Hmm, they now seem to be selling MP1 only, which is chlorine dioxide. "The only disinfection system effective against viruses, bacteria, cryptosporidium, and Giardia. No unpleasant taste." But of course Forte is what is available in Australia at $40 a packet.

I use iodine pills, specifically Potable Aqua (Tetraglycine Hydroperiodide). I use them as a primary treatment method, not as a backup, since the water where I usually walk is of high quality. Iodine pills are cheap, lightweight, easy to find in stores, and stable for several months after opening the bottle. They are very effective against most bacteria and viruses with a 30 minute holding time. They don't fare as well against Giardia and are ineffective against Cryptosporidium.

The chlorine dioxide pills that are available are considerably more expensive than iodine. They also require a 30 minute holding time for killing bacteria and viruses. They are more effective against Giardia and Cryptosporidium but require a 4 hour holding time for these, which (for me) makes them no more effective in practice. They are less toxic than iodine if accidently spilled into the environment.

If one waits 30 minutes to drink, the two types of chemical disinfectants are essentially equal in terms of effectiveness. But the iodine is much less expensive. The taste is not as good, but this is easily remedied by the addition of either the Potable Aqua PA tablets or (equivalently) a very tiny pinch of crushed vitamin C tablet dust after the 30 minute holding time.

As a backup method, the cost difference is less of an issue. The chlorine dioxide tablets come in individual sealed foil packets which makes them very convenient to carry. They remain stable longer than an opened bottle of iodine pills. Iodine pills must be kept in a glass container and protected from UV liqht. Once opened they degrade after a few months. The Potable Aqua glass bottle is relatively heavy (27g). Even if one transfers them to a lighter glass vial it is still heavier and clunkier than foil packaging.

If it were me I'd go with the chlorine dioxide as a backup. How often does your filter or Steripen fail anyways?


That's a good question about the (presumably unlined?) aluminum bottle and chemical disinfectants. I know that some plastic bottles take on an iodine tint and taste. PET (soda) bottles don't seem to have this problem fortunately.

I personally would not use chlorine in an aluminum bottle, chlorine is very reactive as is aluminum. you'd probably be ok for a couple uses in an emergency, but it would suck to get pin-holes in your water bottle while on a trip. plastic is always a good choice for chemical treating IMHO as you can get a good visual of whats going on with your water. I've never had much luck with tablets, the foil on the MP1s is not all that robust (until you try to open them) I use a filter as primary, and boil as a backup. but then where I used to go, crypto, and giardia were the main concerns.

Gadgetgeek wrote:I personally would not use chlorine in an aluminum bottle, chlorine is very reactive as is aluminum. you'd probably be ok for a couple uses in an emergency, but it would suck to get pin-holes in your water bottle while on a trip. plastic is always a good choice for chemical treating IMHO as you can get a good visual of whats going on with your water. I've never had much luck with tablets, the foil on the MP1s is not all that robust (until you try to open them) I use a filter as primary, and boil as a backup. but then where I used to go, crypto, and giardia were the main concerns.

It probably depends on the concentration. For example, you can use household bleach as a water disinfectant and the usual recommended concentration is just a few ppm. This is also a common concentration found in municipal water. The tap water where I live averages a few ppm of chlorine and, not surprisingly, I've never seen any corrosive effect on aluminum cookware.

It's also worth noting that chlorine dioxide is NOT the same as chlorine. They're different chemicals.