What is the correct method for disinfecting a five-gallon water can with iodine tablets?

The correct method for disinfecting a five-gallon water can with iodine tablets involves dissolving a specified number of iodine tablets in a smaller amount of water, such as from a canteen cup, and then adding that solution to the larger container. Iodine is a proven disinfectant that effectively eliminates harmful microorganisms. When using iodine tablets, it's crucial to ensure that the concentration is adequate to provide effective disinfection, which is why the method indicates dissolving 40 tablets before adding them to the five-gallon can.

In this context, other methods listed as options are not recommended for this specific purpose. Using boiling water can effectively kill pathogens, but it may not be practical for large volumes like a five-gallon can, especially without proper handling. Adding food-grade bleach is a valid disinfection method but requires careful measurement and waits time that is not specified here. Using UV light can purify water, but this method requires specific equipment and conditions to be effective and isn't feasible for all situations. Thus, dissolving iodine tablets in a canteen cup and adding them to the water can ensures the least complicated yet effective disinfection method for a five-gallon water can.