Chlorine-releasing compound can not be relied upon in semi-tropical and tropical areas.
Water in those regions must be sterilized either by boiling or by iodine water purification tablets containing the active ingredient Tetraglycine Hydroperiodine, These measures have been adopted as standard by the armed services of the USA.
These tablets have been proved effective against all the common water-borne bacteria. Added to water each tablet frees 8 milligrams of iodine which act as a water purification factor.
One tablet will purify one quart of water. These tablets too must be kept dry. The bottle must be recapped tightly after opening.
Step 1 Add one tablet to a quart of water in container with cap.
Step 2 Wait 3 minutes.
Step 3 Shake water thoroughly, allowing a little water to leak out and disinfect the screw threads before tightening the cap.
Step 4 Wait 10 minutes before drinking or adding beverage powders and if water is very cold, wait 20 minutes.
Step 5 If water contains decaying vegetation or is murky and discolored, use 2 tablets for every one quart.
Step 6 Make certain that the iodine disinfects a good amount of water.