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Net Zero Water is Coming

July 8, 2014 | 7 comments

Net zero energy is being discussed in green building circles more than ever before, with 18 buildings now claiming the title (and several more working toward it). But the newest net-zero buzz? Net zero water. Buildings using net zero water use only the water they are able to generate or capture onsite.

As the International Living Building Institute’s Living Building Challenge becomes more popular, so does the concept of net zero water (to achieve the Living Building Challenge standard, a building needs to be net zero water).

The first step in achieving net zero water is conducting a water audit. Evaluate plumbing fixtures, potential leaks, exterior landscaping requirements, and monthly water bills. Then, just like with net-zero-energy buildings, the focus for net zero water turns to reducing usage. To minimize the amount of water that needs to be generated or captured onsite, water conservation is an important part of the process. It can be achieved through:

  • Installing low-flow or WaterSense toilets, urinals, and showerheads (or consider waterless urinals)
  • Investing in hands-free fixtures to help tenants or occupants who forget to turn water off or leave it running
  • Reducing irrigation by investing in a WaterSense irrigation controller and designing water-smart landscapes
  • Focusing on energy-efficiency measures that will reduce the need for HVAC (which will ultimately reduce the amount of water
    these systems use)

Once usage has been reduced, the final steps include investments in capture and reuse systems, as well as in water recycling systems.

Capture and reuse systems collect rainwater, and then filter, sterilize, and store it for use in places that don’t require drinking-quality water (toilet flushing, irrigation, etc.).

Greywater or blackwater recycling systems can also used to achieve net zero water in commercial buildings. Greywater systems reclaim and treat water from sinks, laundry equipment, and shower drains. Blackwater systems treat and disinfect wastewater containing bacteria and bodily waste. Once these systems purify and filter the reclaimed water, it is then used for non-potable applications: irrigation, cooling systems, flushing toilets, etc.

In addition to saving money, net-zero-water facilities also help limit the consumption of freshwater resources (reducing demand on municipal systems) and return water back to the same watershed so that groundwater and surface water resources aren’t depleted.

Have you heard of net zero water? Do you think it’s an achievable goal?


  1. Scott Yollis
    July 19, 2014

    Everything is a tradeoff and netzero water might make sense in some places but in order to get there most large buildings would have to give up evaporative cooling and rely on very expensive and polluting energy hungry technologies.

    Is it really a good idea to focus on saving water where it’s plentiful and power is the more valuable resource.

  2. Vista
    July 21, 2014

    Hi Scott. Thanks for reading and sharing your perspective. You raise some excellent points. It seems as if net zero water would be something to more strongly consider in areas where water resources may be reduced in the future.

  3. Uddipan
    August 19, 2015

    Appreciate the effort to achieve zero waste to water. but need to emphasize how water will be put back to the ground? Or what is methodology involved to put back high salinity RO reject water to the ground. would it be expensive?

  4. Simon
    August 20, 2015

    Reuse (recycle) shower water is one of the best approach toward net zero water. In theory, it collects used water under a bathtub or shower pan should work. However, there are many difficulties involved. Subject to city official inspection due to plumbing modifications.
    I have developed a Hybrid water reuse system that shuts off water when user is not under a shower head. Also the system captures all shower water saved for toilet flushing and garden irrigation in completely automated operation. No plumbing modification, no filter to buy. 100% Hand free operation. Small production run for testing since May 2015. Waiting for feedback.

  5. Steve Stevens
    August 21, 2015

    Here in Colorado, it is officially illegal to collect rain water … although it is done in many areas… in “Back Yards”. The law indicates that the folks with the oldest water rights on a waterway have the right to all the water as it falls from the sky. Thus a baby in a stroller sleeping with its mouth open, if a drop of rain hits its mouth, has stolen from the downstream users.

    This (Strange but true) situation, along with the historic dryness and current trend to more dryness with climate change, makes Net Zero water a real challenge. Additionally, the cooling here is most efficiently achieved with Evaporative Coolers.

    In my case, I have tried to update my 1979 2 by 4 frame building to be energy super efficient (Converting walls from R-9 to between R-60 and R-104 (up to 26 inches thick!) with Poly-Iso overlays. This makes the cooling load as well as heating load be reduced by up to 96%. Still, when it is over 95 degrees (2 years ago we had 3 days of 105) I need to run the Evap Cooler for 2 to 5 hours I the night (the most efficient time to run it).

    Sound minds have tried to change the water law – but it is pretty firmly embedded here and in other Western states.

    Also, because I converted the lawn to veggies, vineyard and fruit trees (Local Food), I need some water for irrigation.
    I do have 3 (illegal) 275 gallon recycled liquid “totes” which I do collect rainwater into. But when you have a summer with NO RAIN for 60 days or more, water capture is just going through the motions.

    Our water availability in the future (climate change) may be reduced… which does not make the current situation easier to address.

    We need legal relief… and then it will still be a challenge…potentially insurmountable.

    I have gotten to well beyond “Net Zero” on energy on the 1979 structure… and it powers 2 plug in cars. I have addressed transport (Bikes and Plug in cars)… and started on food … hard to get it all on 0.19 acre city lot. But water seems to be a real problem given the food aspect and the legal aspects in a High Desert area.

  6. Vista
    August 21, 2015

    That’s a great question – and one we don’t have the answer to (here at Vista Window Film, anyway). We’re hoping that a lot more will be revealed about net zero water in the next few years as it becomes something that commercial buildings begin considering.

  7. Vista
    August 27, 2015

    Steve, thanks for the insight. And congrats on all of your water conservation accomplishments!

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