What is the total time required to purify a canteen of water using iodine?

The total time required to purify a canteen of water using iodine is indeed 25 minutes. This procedure typically involves adding tincture of iodine to the water and allowing it to sit for a specified period to effectively eliminate pathogens.

The 25-minute duration ensures that the iodine concentration can adequately interact with potential microorganisms in the water, which is essential for effective purification. This time frame allows sufficient contact time for the iodine solution to work, ensuring safety for consumption.

Other possible durations, such as 15, 30, or 45 minutes, do not align with the standard guidance for iodine purification, as they either underrepresent the necessary time for effective treatment or extend beyond what is typically recommended. Thus, the option indicating 25 minutes correctly reflects established procedures for water purification with iodine in a military context.