Plan ahead to save hassles later
Plumbing systems are complex, expensive, and largely inaccessible when construction is complete. For those reasons, careful planning pays big dividends.
There are two sides to every residential plumbing system: supply and waste. Within those broad categories are a number of subsystems, many of which present opportunities for conserving water, energy, or both.
A well designed plumbing system is capable of saving thousands of gallons of water every year. In many communities, saving water also saves energy because a lot of electricity is used to pump water from source to houses.
With planning, the energy needed to make hot water can be significantly reduced. Solar collectors are one obvious answer, but even in homes with conventional heat sources energy savings can be sizable.
ABOUT SUPPLY-SYSTEM LAYOUT
First, buy efficient appliances
Most of the opportunities for energy and water conservation in a plumbing system arise from specifying an efficient water heater, an efficient clothes washer and dishwasher, low-flow showerheads and faucets, and reducing water consumption. But the distribution system itself also has an impact.
Anyone serious about conserving water should start with the low-hanging fruit; that means that the greenest homes do not include a swimming pool. Omitting a swimming pool will also save energy, since pool pumps, filters, and heaters are notorious energy hogs.