Chemical disinfection can be a very effective method of drinking water purification. However, implicit in the use of chemicals is some level of input from external sources. Such a method requires money, a source, and the ability to import the chemicals. If the resources are available, iodine disinfection can effectively purify water of biological agents. However, inactivation of giardia is unreliable, as in the case of UV systems (Extension Bulletin 795, 2003). This procedure, however, can be made more reliable if the water is allowed to have a contact time of 15 hours or more (CDC, 2003). For individual home use, .25 ml of 2% tincture of iodine (readily available over the counter internationally) is simply added to one quart/liter of clear water (or .5 ml added to one quart/liter cloudy water). The solution is then shaken and allowed to sit for thirty minutes for immediate disinfection. As mentioned above, this technique will only eliminated giardia spores if allowed to sit for 15 hours or more (CDC, 2003).
There are many issues surrounding the use of iodine in drinking water disinfection. The diets of many living in underserved areas of the developing world suffer from iodine deficiencies, leading to giant goiters (Wilson, 1941), birth defects, miscarriages, and a host of developmental disabilities (NCCDP, 2003). As one remedy, the National Cambodia Community Development Project recommends iodine addition to village water supply. So, in areas identified as deficient in dietary iodine, this method of drinking water disinfection may be advisable and doubly beneficial.
(Typical iodinator intended for use in a small –scale
community drinking water supply system. From
Ohio State Onfline.)
At present, there are no proven adverse health effects associated with iodine (Extension Bulletin 795, 2003). However, it is an active chemical in the human body and it has been widely speculated that it may have some negative and as yet undetermined health effects. For this reason, Health Canada cautions: “iodine disinfection of drinking water should be reserved for emergency and occasional use. Iodine should not be used for long-term continuous disinfection because it is physiologically active, and ingestion in excessive amounts may be harmful (Health Canada, 2003, Extension Bulletin 795, 2003). Iodine can be injected in greater quantities into a larger scale water supply system. “Iodine solutions are injected into a water system using bypass saturator systems or injection pumps. A holding tank or coil of pipe is used after iodine injection to provide the necessary holding time” (Extension Bulletin 795, 2003). Such a system is somewhat complicated, although it may be feasible if the community has enough money and the relevant expertise to install and maintain iodinater(s). However, given the contentious nature of iodine use in drinking water disinfection, it seems safe to say that it is not exactly the most sustainable solution.
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