Yes Mai, you bring up a key element of all this which is that no one solution to the problem exists. We need a range of alternatives, each better suited for one environment than another. One person mentioned that folks who live in and/or near wooded areas will not receive much sunlight so we reasoned that they could burn the wood to cleanse their water. It's a renewable resource in abundance in their area so should be OK. Some of these solutions will involve 3d printing as part of the development or production process, while others will not.