"Water, Water Everywhere, Nor Any Drop To Drink"
By Dr. L. Morris Johnson
Don't put yourselves in the plight of Coleridge's Ancient Mariner by being unable to drink safely because you either don't know how or forgot the necessities to purify your water!
What do we need to know about our water supply? First, all water sources that are not known to be potable (suitable for drinking) are potential sources for water borne diseases in California and most other places you might visit on outings and backpacking trips. Contaminated water supplies may harbor:
- Protozoa such as giardia and Cryptosporidia.
- Bacteria such as cholera and Salmonella.
- Viruses such as hepatitis.
Protozoa are larger organisms and are easily removed with filters having a pore size of one micron. Bacterial and viral contaminants may pass through all filters and must be killed by purifiers or chemical treatment.
The simplest method for short-term water purification is the use of iodine as tetraglycine hydroperiodide tablets (Potable-Aqua). One fresh tablet fully dissolved in a liter of water provides an iodine concentration of 8 mg/L. This concentration will effectively sterilize your water, but does impart an iodine taste. One must wait approximately 30 minutes before drinking water so treated and longer if the water is cold. Two tablets can be used, but time is still needed for disinfection.
A tiny bottle of 50 tablets is easy to carry. It must be kept tightly sealed as the compound disassociates when exposed to air - as much as a third of its effectiveness may be lost in four days if left exposed. Always obtain a fresh unopened supply for your trips.
Be certain that all persons purify their water in the proper manner!
Drinking iodine treated water too quickly after treatment or not treating all water may lead to a sick individual, and only one is needed to have an unhappy group!
When weight is not a significant problem, water filters, of which there are several available in a range of prices, may be convenient and produce better tasting and visibly clearer water. The care of the filter, spare parts, time consumed pumping, and group water distribution need consideration.
A filter alone will be adequate for the removal of protozoa, but a purifier attachment is needed to destroy bacteria and viruses. Although an iodinated resin is used in most purifiers, the iodine is less concentrated than in tablets and less likely to be tasted. Furthermore, a carbon filter component can be added which helps in removing some chemicals, herbicides, pesticides and the taste of iodine.
Boiling will remove all water pathogens, but is time and fuel consuming as well as inconvenient.
Finally, although we need to maintain a potable water supply, good hand washing and food preparation will prevent the most common causes of food and water borne illnesses at camp and on outings!
