1.Measure .5 mg to 2 mg of chlorine dioxide powder, liquid or tablets onto a metric scale. Any amount between this range is acceptable, but remember that chlorine dioxide is a stomach irritant. A dosage closer to the low end of the scale should be used if you're using chlorine dioxide for the first time. Your body will eventually build a tolerance. 2.Add the measured chlorine dioxide to 1 liter of water. Measure this water using a measuring cup or fill a container that is clearly labeled as 1 liter. 3.Place the water in a cool, dry spot and leave it undisturbed for 30 minutes. The passage of time allows the chlorine dioxide to interact with the water and kill harmful microscopic organisms. 4.Add water to the mixture to lower the concentration of chlorine dioxide somewhere between .2 mg and .4 mg per liter. The chlorite byproduct will continue killing harmful organisms while the concentration of chlorine dioxide is lowered to an amount safe for consumption.