Green Building Priority #2 — Reduce Water Use
Number 2 on my list of the top-10 green building priorities is to reduce water use.
Reducing water consumption should be a high priority not only in the parched Southwest but throughout the country. Some argue, in fact, that water is going to be an even bigger challenge than energy over the coming decades.
In the United States, nowhere is the focus on water greater today than in the Colorado River Basin. A series of reservoirs on the Colorado, including Lake Powell and Lake Mead, provide water for some 25 million Americans, and allocations of water from the river exceed the available flow. Lake Mead currently stands at half-full, its scenic shore marred by a giant bathtub ring several hundred feet high. A university study a few years ago said there was a 50% chance that the reservoir would be functionally empty (its level too low to draw from) by 2021!
But in many ways, water resource issues are an even bigger problem in parts of the country that aren't as used to thinking about water. In the fall of 2007, Atlanta came within 30 days of running out of water, with no provisions for what to do if that occurred. Eastern reservoirs tend to be a lot shallower than western reservoirs, so have less storage capacity.
Water is such a high priority in part because so much else depends on it. Most of our power plants draw water from rivers and lakes for cooling, and during severe droughts power plants have to shut down. (In 2007 one nuclear plant in Alabama had to shut down for lack of water.) Our food system depends on irrigation—though the U.S. is less dependent on irrigation than China, India, and many other countries. We drink and wash with water. And it takes a lot of water to generate electricity: on average 2.0 gallons per kilowatt-hour in the U.S.
In addition, water is energy-intensive. Pumping water out of the ground, moving it from one place to another, treating it, and then treating the wastewater after we use it accounts for about 4% of the nation's electricity. In many municipalities, water and wastewater infrastructure comprises the single largest use of electricity.
There are lots of good ways to reduce water use. A few of my favorites are listed here:
One of the easiest, least expensive strategies for reducing water use is to replace older showerheads with models that use significantly less water. Some older showerheads use 5 gallons per minute (gpm) or more, while models sold (legally) since 1994 use no more than 2.5 gpm. I've been using a Delta H2Okinetic 1.5 gpm showerhead for years and find it highly satisfactory, even with the low water pressure on my rural water system. Saving water with a showerhead also saves energy—because it's heated water that you're using less of.
If you have a pre-1994 toilet (one that doesn't list the water consumption on it), chances are pretty good that it's using at least 3.5 gallons per flush (gpf). Since 1994, all toilets sold in the U.S. have had to use 1.6 gpf or less. More recently WaterSense-certified "high-efficiency toilets" (HETs) have been introduced that use no more than 1.28 gpm and meet various flush performance standards defined by the EPA WaterSense program. Unless your house has very long drainline runs (over 20 feet) with very low slope (nearly horizontal), choose WaterSense HET toilets.
Reduce the water consumption of bathroom faucets
More and more new lavatory faucets today meet the WaterSense limit of 1.5 gpf, while most faucets in use deliver far more water. Since 1994, faucets could use no more than 2.2 gpm (at 60 psi water pressure), but older faucets often use a lot more. Most relatively modern faucets can be retrofit with screw-in low-flow aerators. You can go as low as 0.5 gpm, which is usually plenty for brushing teeth, washing hands and face, and shaving. Note that the lower the flow, the longer it will take hot water to reach the tap.
Install an on-demand circulator pump
To avoid wasting water as you wait for hot water to reach your bathroom or kitchen, you can install an on-demand recirculation system. Unlike continuous-circulation systems that are used in hotels, on-demand systems are activated by a user. Several companies make these systems, most using D'MAND technology licensed by ACT Metlund.
Buy a water-saving clothes washer
Horizontal-axis, front-loading clothes washers use significantly less water than most vertical-axis top-loaders. They also use half the detergent, and most of them wring more moisture out during the spin cycle (saving energy needed for drying). If you're replacing a clothes washer or buying your first, look for a water-saving front-loader.
Buy a water-conserving dishwasher
Check the energy- and water-efficiency of available dishwashers if you're in the market for a new one. The Consortium for Energy Efficiency (CEE) has the best information.
Plant low-water-use landscaping
In many parts of the country, outdoor water use exceeds indoor use. Native landscaping that does not require irrigation can save a tremendous amount of water, compared with lawns and most other conventional landscaping. The term "xeriscaping" is sometimes used to describe this landscaping practice.
Harvest rainwater for irrigating
If you must irrigate, capture rainwater and use that for irrigating. You can install a simple rainbarrel that sits under a downspout at the corner of your house, or install a more sophisticated system with greater storage capacity.
These suggestions are just a starting point; there are lots of other opportunities for savings. Huge savings can also be achieved simply by changing your behavior: taking shorter showers, and not running the water when washing dishes or brushing your teeth, and skipping lawn-watering, for example. To a significant extent, water savings is about common sense.
My top-10 list of green building priorities so far:
#2. Reduce water use
#3. Ensure a healthy indoor environment
#4. Reduce the need for driving
#5. Build smaller and optimize materials use
#6. Ensure durability and reuse existing buildings
#7. Protect and restore the site
#8. Use green materials
#9. Create resilient, climate-adapted buildings
#10. Make it easy for homeowners to be green
In addition to this Energy Solutions blog, Alex writes the weekly blog Alex's Cool Product of the Week, which profiles an interesting new green building product each week. You can sign up to receive notices of these blogs by e-mail—enter your e-mail address in the upper right corner of any blog page.
- National Drought Mitigation Center at the University of Nebraska
- Delta Faucet Co.
- Taco, Inc.
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