Have you ever wondered what happens with your water once it makes its brief passage through your house? Not the water that resides in your toilet, but the water that you shower or wash dishes with. Water that is not potable, but also not heavily contaminated with chemicals or your bodily waste (ewww). Couldn't this water still be used for certain functions like garden watering or heading back to the toilet (as long as you don't let your dog drink out of it)?
During my brief career of technical sales I have realized how difficult it can be to explain systems in words as opposed to diagrams. The old adage that a picture is worth a 1000 words is true, especially when it comes to systems that include electricity (solar PV or Wind power) or plumbing (solar thermal or geothermal).
My favorite car brand is BMW, so I jumped at the chance to work at their only US production facility in Spartanburg, SC as in intern in college. It was a great experience seeing how some of the nicest cars in the world are made. On my way to my office each day, I would pass their on-site landfill gas --> energy plant.