In another thread, two forumites mentioned they were making inexpensive bucket-based water filters. One source was mentioned here. This is the coolest idea, I would like to make one, too. Those of you who've made this kit: - How do I get started? - Is this a water filter, or water purification system? I'm assuming filter (meaning effective against bacteria and protozoan cysts, but not viruses). So does this require additional treatment?