Most communities in the U.S. treat their wastewater just enough to legally dump it, but not reuse it. Pasteurization Technology Group has developed an inexpensive treatment system that yields water clean enough to be returned to aquifers. Instead of using chlorine, the system pasteurizes wastewater by heating it to 180ºF. The warmth comes from the waste heat of a nearby electricity generator running on either natural gas or biogas produced by an associated sewage digester. A PTG water plant opening next year in California expects to make a $160,000 annual profit by selling its extra biogas-generated electricity. Even if the turbine is fueled with natural gas, the pasteurization is energy-efficient enough to be about half the cost of chlorine treatment.