The Three Methods of Purifying Water

The water filter is his primary source or primary method of cleansing his water so that he can drink it. The second method I talked about, that of water for purification tablets, is not ideal for him to use on a regular basis. But what they are is small, compact, durable, and hard to destroy. Now that brings us to our third method: having a vessel in which he can boil the water. This is a good form of complementary redundancy because it not only complements the other methods. It's redundant because he could use just that method alone to provide him with clean water.