It all depends on the argument you want to make. I would probably start with all the possible positions you could take. Here’s an example I have thought about, Should houses be required to have point of use water filtration systems, so water used for non consumption uses, (watering lawns, washing cars, etc.) don’t need to consume government resources to purify? I don’t really have an opinion, but doing the research on how much we spend to purify water, how much point of use systems cost, and how would switching our filtration process would effect our carbon foot print would probably help me to form an opinion.