This maybe a little out there but I'll ask anyway. We have been thinking about getting a geo-thermal system for our home and I stated thinking of better ways and wondered why A septic tank is never incorporated into the design other than the obvious answer. I know our family of four uses alot of hot water every day on average 4 showers,a load of dishes,laundry,washing hands. why cant all that hot water be used to help heat the loop instead of wasted down the drain? I know the tank will usually melt several inchs of snow in the winter time so it must be warm in there. Seems like I heard that the process of braking everything down in there also produces heat. I'm not saying it would eliminate the loop needed just help supplement it. Maybe a shorter loop or shorter run times for the geo-thermal unit. Is this something that has been thought/tried before or is there something I dont realize that would make this impossible? Seems like the tank could easily be insulated before or during an install to help hold in the heat.