Ok so it uses a heat exchanger to heat water and then distributes it to the customers who have water heaters? I guess it could save a little energy but foregoing this process and investing in biodigestion makes way more sense. Not to mention drinking water plants and wastewater treatment plants aren't typically connected like this...

Skip to biodivestion and use the energy from that for electricity and not just hot water. Several wastewater plants have done this and power their entire plants and have leftover energy to sell back to the grid.