 Soon Sim's neighbor built one, and people started calling for plans.The virtues of the system were that it saved ten to fifteen thousand gallons of water that otherwise would disappear down the toilet each year; it reduced the need for large leach fields, and it literally made people responsible for their own excrement, an idea that was attractive to libertarians, organic purists, outlaw builders, and people engaged in reexamining and redesigning all aspects of their daily lives.