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Energy Solutions

Green Building Priority #2 — Reduce Water Use

Number 2 on my list of the top-10 green building priorities is to reduce water use.

Image 1 of 3
U.S. drought map, updated weekly, from the National Drought Mitigation Center at the University of Nebraska.
Image Credit: National Drought Mitigation Center at the University of Nebraska
U.S. drought map, updated weekly, from the National Drought Mitigation Center at the University of Nebraska.
Image Credit: National Drought Mitigation Center at the University of Nebraska
The Delta H2Okinetic showerhead uses just 1.5 gpm, but provides a very satisfying shower. I've used one at home now for four or five years and am very satisfied.
Image Credit: Delta Faucet Co.
The D'MAND system, developed by ACT Metlund, allows you to get hot water to a distant bathroom or kitchen very quickly without wasting water. Shown is the model sold by pump manufacturer Taco, Inc.
Image Credit: Taco, Inc.

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:

Replace showerheads

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.

Replace toilets

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.

Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. To keep up with his latest articles and musings, you can sign up for his Twitter feed.


  1. Jan Juran | | #1

    Good Summary
    Many thanks for the astute summary, Alex. I switched to the Niagara Earth 1.5 GPM showerhead in my house and the performance was as good or better than the older inefficient models. More recently I switched again to the newer Niagara Earth 1.25 GPM showerhead, again with zero diminution of comfort and efficacy (also confirmed by several household guests). The Niagara 1.25 model is a great value at $11 or so. Apart from a lower water bill, the hot water energy savings are quite significant, and my existing hot water heater can eventually be replaced by a smaller capacity model at reduced capital cost. Reluctantly I admit that the 0.5 GPM bathroom faucet aerator I'm currently using does not perform as well as the 1.0 GPM model it replaced. I've been trying to find another aerator in the 0.6 to 0.75 GPM range to achieve the no diminution of desired end result criterion, but without success so far.

  2. A non mouse neo-dadaist | | #2

    Not throughout the whole country.
    Your first sentence is simply not true for the WHOLE country. And we are a far cry from being a desert country. For example, how many homes in the USA have cisterns since there is such a dire situation? I bet there are more cisterns in the Carribbean than the USA. Why do they have cisterns? They needed them and they made economic sense that's why. And as we need water like along the Colorado River the economics will provide for it in it's due time. If you want people there to conserve faster tax the water till the cost makes it so... or wait till that happens anyway.

    My shower head is modified to really rain down a deluge. I Love it. And I am not hurting the world one iota. OK.. so I should get my solar water heat system up and running and will... then... we be green and we be showering in water my way.

    We all do not need to save water. That is pure malarchy.


    A non mouse neo-dadaist
    That is pure malarchy.

  4. Steve El | | #4

    I agree that we are not
    I agree that we are not destroying the earth's supply of H2O molecules, but we are definitely destroying easy-to-access, cheap, clean water. Mouse, if you are happy to eventually have the nation incur the cost of infrastructure to treat and pipe water all over the place, then by all means, let that shower run. If you think those dollars would better serve the nation by reducing the federal deficit I hope you'll do your part and install a low-flow unit. But I do agree the H2O molecules themselves don't care a whole lot.


    They actually had a battle over rain water harvesting in Colorado. Prairie farmers argued that mountain dwellers were illegally stealing rain that fell on the mountain properties, preventing that same rain from being available to irrigate the farmers downstream crops.

    Can you imagine? This ain't no small potatoes..... even the legislature got involved.


    Just a guess..... If the stereotypical white middle class family of four went from eating the average amount of factory farmed animal flesh to a non-meat diet, I bet that would reduce that family's water use more than all of the home-improvement type conservation measures combined.

    If so, then green diet should come before green dishwasher.

  5. Lucas Durand | | #5

    A common fallacy.

    And as we need water like along the Colorado River the economics will provide for it in it's due time.

    This is what I now call the "we can always buy ourselves out" Fallacy. This fallacy is based on an assumption that there will always be money and materials to do whatever we want or need to do to get by. It can also be based in a strong faith that "the market" will solve all problems.

  6. Lucas Durand | | #6

    Well said.

    Just a guess..... If the stereotypical white middle class family of four went from eating the average amount of factory farmed animal flesh to a non-meat diet, I bet that would reduce that family's water use more than all of the home-improvement type conservation measures combined.

    That is an excellent guess. I'll bet it wouldn't be too difficult to prove this.

  7. Lucas Durand | | #7

    Water energy connection.
    Alex, thank you for mentioning the water-energy connection. There is easily a full blog report on that topic. This connection is an important one to understand because it is a great complicator of things.
    Almost every form of energy we produce requires water as an input, from tar sands and biofuels to nuclear and coal plants. From the other end, almost all the water we consume requires enegry as an input for pumping and treatment.
    I don't think it's a stretch to say that most people in the "developed world" take fresh water for granted. It's time to break this bad habit and start appreciating all the things water does for us (besides moving poop into the sewer).

  8. Alex Wilson | | #8

    Water energy connection
    Here's a blog I wrote specifically on the water-intensity of energy:

  9. a non sequitur mouse and peach pit | | #9

    water water is not scarce EVERYWHERE!
    Water where I live is beyond plentiful!!!@@@ Meaning- It is not anywhere close to scarce and every drop is LOCAL!

    No matter how much we use in this region we are NOT AFFECTING any other population on the entire planet. Our water and all water has an area that shares it. Our area has too much period.

    We don't need to save water just because some areas do have to do we?

    No, we don't. And no apologies.

    Yes, if you live in q densely populated desert like Vegas, you better have a good water plan.

    I do not live in a desert.

  10. Steve El | | #10

    "our area has too much
    "our area has too much period"

    What area would that be?

  11. Alex Wilson | | #11

    Water scarcity
    In these comments, it would be great if those commenting could divulge where they are based.

    We tend to think about water scarcity only in the Southwest or west generally, but Massachusetts was actually the first state to impose statewide water conservation laws to limit the flush volume of toilets and the flow of showerheads and faucets (that Massachusetts law became the model for the Energy Policy Act of 1992, which established the national standards we are all familiar with). In the case of Massachusetts, the driver was limited capacity of the Quabbin Reservoir in Western Mass that provides water to Boston and much of eastern part of the state. Boston was faced with either coming up with another water supply--at a cost of many billions of dollars (and some significant permitting issues!)--or reducing demand. The latter was far cheaper.

    While 20 inches of rain in a year in New Mexico would be a huge amount, 30 inches in Georgia would be a major shortfall. That's what happened in 2007, when Atlanta came within 30 days of running out of water--with absolutely no contingency plans. One power plant had to shut down for lack of cooling water and dozens more were close to that point. Eastern reservoirs tend to be a lot shallower than western reservoirs, so there is not as much capacity and the level drops more quickly if inputs are lower. The governor of Georgia led prayer vigils to bring on the rain (and it apparently worked). Some years earlier Seattle (another generally wet place) was struggling to cope with an unexpected drought.

    With climate change, precipitation patters are expected to change. Some places will get a lot more rain. Others (models suggest a lot of the west) will get less. Many areas will get their rainfall very heavy short-duration bursts that are harder to capture in aquifers before it runs off.

    Mark my words: over the next decade, there will be places where water has never been a point of discussion where governments will be scrambling to figure out how to cope with shortages. If we don't think about this today, our children and grandchildren will marvel at our shortsightedness--and pay the price for it.

    Posted from Brattleboro, Vermont, where water is usually plentiful.

  12. 5C8rvfuWev | | #12

    Further evidence Georgia is Superior to Massachusetts
    Alex, although Massachusetts (while I lived there) frittered away valuable time and taxpayer dollars by promoting water conservation, however minimally, the governor of Georgia (while I live here) not only led prayer vigils but courageously filed suit against neighboring states. The suit contended that the survey which set state lines -- some 200 years ago -- was wrong! The state of Georgia further contends, as I read in local papers, that the Tennessee River (around Chattanooga) actually belongs to Georgia and the state has a right to its water! Fortunately, it rained before Georgians marched on the people stealing our water.

    Lucas mentions the "we can always buy ourselves out" fallacy, but our governor doesn't believe in taxes, so we use the "there's no problem that can't be solved by litigation or war" fallacy.

    Good luck with the common sense approach, but ....

    (For those who don't notice sarcasm, there is a point to be made about how unfortunate it is that public policy is shaped by local opinion and the need for popularity among voters rather than by expertise or leadership. Apologies for however off topic this is.)

    An excellent blog, as the entire list has been. Thanks.
    Joe W

  13. Steve El | | #13

    Example of rainfall tipping point hot off the presses
    Hot off the presses, new research about the details of a historic pattern of tipping points that has cut off water in the past, and presumably will do so again if the area warms by 1.5 C (at current rate estimated to happen in 30-40 years). Two million people would have their current water supply vaporize if that happens.

  14. Kevin Dickson | | #14

    Links to Water Info
    Gary Klein has studied this in depth:
    I've written a bit about saving water in Denver :

  15. a no nothing punk | | #15

    less people is a good thing.
    This planet has some huge gallonage of H2O. Getting useable water from the oceans is done already and time had only reduced the cost and will continue to do so via Moore's law.

  16. Lucas Durand | | #16

    Where will all this money come from?
    AJ, please feel free to present some evidence that supports your position.
    Desalination is a great example of a solution that makes perfect sense to someone who believes in the "we can always buy ourselves out" fallacy. Desalination of ocean water is the most energy intensive and expensive way you can produce fresh water and in a future of constrained energy resources makes almost no sense at all.
    Here is an interesting read on the subject: (Note: "AF" stands for "Acre-feet")
    Salient quotes:
    "Like corn ethanol, ocean desalination would not be remotely competitive without huge subsidies. In this case, $250 per acre foot plus publicly constructed and operated pipelines. So much for the pledge of, “no taxpayer money.”

    "Ocean desalination is an example of our complete failure to recognize stark realities—water, food, energy, soil, air, and oceans are limited and our population and consumption keeps growing. Once again we are applying a technical fix to an adaptive challenge."

    "We are rapidly approaching the time when we will not have enough money to throw at our problems."

  17. Anonymous | | #17

    Subsidy quoted above is rediculously meaningless
    $250 for 1 acrefoot equals one penny per 13 gallons.

    Water is incredibly inexpensive to provide even from an ocean.

    Water saving is not needed. Birthcontrol is via revamping religions to limit their flocks reproduction.

    Control the flock size and their is less if any problem.

  18. Lucas Durand | | #18

    A current surplus is no guarantee of a fututre surplus
    The $250/AF is only the cash portion (not including public pipeline contruction and maintenance) of a subsidy to the total cost. The contract in question (City of Huntington Beach) is for 50 million gallons/day which (using your 1 cent/13 gallons) works out to almost $40000/day (cash subsidy only). Total cost for desalinated water is in part determined by salinity of water and cost of electricity. For operational plants, cost for desalinated water ranges from $1100-$6000/AF.
    If you have been paying any attention to what people have been saying so far you will realize that energy and water share a special connection. In the future, if the cost of energy increases (as it certainly will) the cost of water will increase as well. Energy intensive forms of water purification (like desalination) will not be sustainable.

  19. Deniz Bilge | | #19

    How 'bout getting back to factual information...
    What do you do with ALL the salt?...I think there is plenty of water; it's just not used properly. Why we use drinking water to flush our toilets is beyond me. How 'bout the pollution in all our rivers, streams, creeks....How 'bout changing our attitiude from how to provide more resources to how to conserve them. I'd rather live in a house that uses 5000 kwh per year than live in a house that uses 15000 kwh per year, with a solar system that offsets 10,000 of them.

    Anyway, moving on to my situation, if anyone can help. I'm building new, and I've already installed a 1400 gal underground cistern (potable rated). I want to use this water not only for outside purposes (hose bibs, outside shower, irrigation), but also to flush toilets, shower, dishwasher, and washing machine, and my fire sprinkler system. The city needs a schematic, but they are weary about me bringing this water into the house. What is acceptable in code to accomplish this? Can I just use copper for my metered water and pex for the water from the cistern? Plumbing is one of my weak links, and information on how to comply with the city code is definitely appreciated.

  20. Doug | | #20

    Purple REX is designed for Grey/rainwater lines to keep them seperate from potable water lines. Also, the IAPMO plumbing code adresses rain water. The current issue of the Journal of Light Construction has a good article on rainwater harvesting.

  21. Anonymous | | #21

    Fear mongering nuts
    Lucas, I am using YOUR figures and making them REAL versus SCAREY... like the boogie man in the your closet. First you quote $250... then I show that it is only 1 penny for 13 GALLONS!!!! and so now you run the number up to $6,000. OK.. at that number we are talking 2 cents a gallon. which is not the end of the modern world!!!!!

    The sky is falling talk has been going on since man hit this planet centuries ago.

    Where I live we have enough water in one lake to drink for a thousand years. Water is not scarce everywhere. It is a regional issue and is always available if the work is done to make it so. People subsist in deserts for crying out loud zipping around on camels...

    Sorry... my sky isn't falling and if it does and hits me on the head... who cares.. as I am carefreely dead at that point and thereafter thank you.
    a non believer

    ps... saving energy, less people.. less taxes... and less signs on ladders telling me not to use the last two very useable steps that I paid for!!!!

  22. Lucas Durand | | #22

    Response to AJ
    AJ, if facts scare you that isn't my fault. Nor is it my fault if you cannot multiply 1cent/13 gallons by 50 million gallons. Nor again is it my fault if you do not understand the difference between a subsidy and the total cost.
    If you don't like my facts, try coming up with some of your own for a change.

  23. Lucas Durand | | #23

    I've been called a nut by people smarter and more wise than you. Don't be disapointed if I'm not crushed by your name calling.

  24. A dog in a pony show | | #24

    Quoting you Lucas... "For
    Quoting you Lucas... "For operational plants, cost for desalinated water ranges from $1100-$6000/AF."

    Wikipedia... "The exact number of gallons per acre-foot equals 325851.385 gallons."

    Me... and my math.. $6,000.00/325851.385 gallons=1.84cents/gallon. (your worst case)


    OK.. DOUBLE IT.... 3.7 CENTS/GALLON (twice your worst case)


    AND AGAIN... NOW WE ARE AT 59CENTS/GALLON (16 times your worst case!)



    THE dog

    ps.... my IPAs cost over 512 times more than your supposedly high priced drinking water. No one will flush toilets full of drinking water when economically it makes sense not to Lucas.

    LOL... you think I am worried? LOL... yaa right... about your blood pressure maybe.... join me for a cold one bro.

  25. aj builder | | #25

    1/3 cent per liter
    Technology..... at work... Moore's Law....

    great people doing a great service to and for the world community

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