Structural waste concerns water and energy that are wasted by how the plumbing system is laid out. If the water heater is at one end of the house and a bathroom is at the other, a lot of cold water can run down the drain while hot water flows to the bathroom. If a recirculation line is running all the time, enormous amounts of heat can radiate away from the piping. Structured plumbing and demand pumps can improve the situation in many of these cases.
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