Net Zero Water & Landscape Architecture

Los Angeles panorama image: Gary Lai
Los Angeles panorama
image: Gary Lai

I just hosted an event where twenty-five people watched a video of a flushing toilet and gave it a standing ovation. Granted, I live near Hollywood in Los Angeles, but this was not a showing of some avant-garde cinema (today’s Hollywood cinema could never be confused with avant-garde; perhaps, if Captain America were flushing the toilet). This was a combined USGBC and Living Building Challenge meeting to figure out how to get to Net Zero Water in LA.

The toilet in question was a composting toilet that uses no water, but a highly evaporative alcohol lubricant to flush the waste into a digester unit in the basement. Gross? Maybe, but we Californians have to come to terms with the inevitable conclusion that our state’s multi-trillion dollar, 100 year-old water infrastructure system transporting Northern California snowpack to Southern California bathrooms will not be enough. California holds 10% of the country’s population, provides 40-60% of the nation’s fresh fruits and vegetables, and has a big enough industry and economy to be rated 8th in the world. California will only continue to get more populous, hungrier, and thirstier over time; the flushing composting toilet was not only grand entertainment for us but a hopeful sign that we will be able to solve our water resource problems by being smarter designers.

What does this have to do with landscape architecture, you may ask? Well, we landscape architects and related industries need to be smarter and more careful in the conservation of our water resources.

Hollywood sign image: Gary Lai
image: Gary Lai

While landscape water does not account for the bulk of a daily water budget for a single building or residence (that prize goes to toilet flushing), it does demand a constant supply for a long period of time. In the case of exotic plants or lawns, the demand increases as the exotic plants grow or as the turf maintenance inevitably tails off. By some estimates, landscape water can be up to 40% of the potable water use for a single family residence over the course of a year.

Turf lawn is the number one irrigated crop in the US, even though it produces no food and has no other direct economic benefit. You could make a case that turf has some economic benefit through the installation of recreational facilities such as golf courses, but if you did an economic analysis on the amount of acreage required for a golf course per the amount of money that area would generate for other uses, I’m sure you wouldn’t necessarily classify a golf course as an economic driver. One of the main reasons that we have a considerable amount of turf in projects is purely because of the aesthetics and the mentality that it is recreational. There is no substitute for turf in sports fields (artificial turf is another discussion all together), but why does it have to be everywhere?

A drought tolerant backyard image: Gary Lai
A drought tolerant backyard
image: Gary Lai

This weekend, I drove down a residential street in Burbank where every house (large and small) had a green front lawn. If you did the quick and dirty math on turf’s water demand using the coefficient method described in the State Model Water Efficient Landscape Ordinance (AB1881, 2009), turf uses approximately 1,000,000 gallons per acre per year in Southern California. Even if you add a large margin of error on the calculation, you are looking at a large demand that never goes away in a place that can scarcely afford it.

Many individual landscape architects and landscape architectural firms have been pioneers and practitioners of water-wise landscapes, but as a group we have been relatively quiet. Recently, sustainability consultants and architects have had a larger influence on local landscape water policies than us. This spring, I will be attending a lecture sponsored by AIA discussing the Australian mega-drought and how lessons learned from that experience can be used in the United States. As landscape architects, we must reinsert ourselves into the conversation by embracing good water conservation principles in our designs and finally abandoning our obsession with imported aesthetics. We should also look to cross-pollinate with our allied professionals in research and presentations so that all elements of design (from the building to the landscape) are inclusive of these conservation efforts while all professionals are represented for their work.

Los Angeles City Hall image: Gary Lai
Los Angeles City Hall
image: Gary Lai

A few additional actions that we can take include:

  1. Manage the client’s aesthetic expectations: Why is the English Country Garden aesthetic the default? We must advocate for a wide assortment of aesthetic schemes that will meet the client’s needs yet have a reasonable water overhead.
  2. Reduce the use of turf lawn: Turf that serves a functional purpose and is sized reasonably for that purpose will drastically reduce the project’s overall water footprint. Turf should not be a default.
  3. Embrace the use of native and native-adaptive planting: There are a variety of plants available in the Southwest US Bioregion and there is no reason to steadfastly stick to exotics.
  4. Understand our irrigation options: Integrating sound irrigation technology and design in the conceptual stage will give us a much more water efficient design.
  5. Understand our water reuse options and how they might be incorporated into the overall design:
    – Stormwater
    – Recycled water
    – Condensate water
    – Rainwater capture
    – Water storage
    – Waste water reuse
  6. Understand the soil conditions: Water runoff from poorly maintained and designed irrigation systems is a major concern and we need to understand soil permeability and water holding capacity.
Drought tolerant planting at the Los Angeles Arboretum image: Gary Lai
Drought tolerant planting at the Los Angeles Arboretum
image: Gary Lai

Now, let’s go back to that composting toilet. Obviously, to get to a balanced system, supply must equal demand. California gets all of its water between October and March. However, during the hot summer months when demand is the highest, our supply is next to nothing. The equation is simple: in order to balance it, you must reduce demand and increase supply. Suddenly, the majority of water demand disappears with composting toilets, hence the clapping. Now, don’t get me wrong—there are so many hurdles to overcome to get a composting toilet system built and installed that it makes a WWI minefield look like a 100m sprint course—but at least we have a viable starting point to get to Net Zero Water. We all know that trying to get that last 10% of either savings or supply will be the most difficult and costly, but in many ways, our industry tends to make things much more difficult than originally planned.

Landscape water conservation is easy and relatively inexpensive. We now have a vast palette of native, native-adaptive, and drought tolerant plants readily available that will meet the vast majority of design requirements of our clients. We also have access to irrigation technology that is smarter and more efficient than ever before. And finally, we have an interested and engaged public and public agencies that are looking to us to be leaders and educators. There is no better moment in history for us to stand up and become true stewards of the land.

by Gary Lai, ASLA, Water Conservation PPN Co-Chair

7 thoughts on “Net Zero Water & Landscape Architecture

  1. Jodie Cook April 21, 2015 / 4:03 am

    Great article Gary! At the moment water districts are taking the lead in spreading this info to homeowners via California Friendly Landscape Training Workshops being held weekly throughout SoCal. They are free and a great way for the general public to get up to speed quickly.

    • Gary Lai April 30, 2015 / 4:47 pm

      Thanks, Jody! I also think the Water Districts and other AHJ’s should be talking about a water conservation certificate and training for landscape architects, contractors and maintenance companies and personnel.

  2. john irvine April 21, 2015 / 6:19 pm

    Good stuff Gary. We need to keep discussing, spreading the word, training and acting on our knowledge!

  3. Limassol Architect April 27, 2015 / 7:16 am

    Excellent post, with tons of interesting facts and tips.
    And that opening… hilarious!
    Thanks for sharing!

  4. DAVID W CAMPBELL May 18, 2021 / 8:14 pm

    Gary, I appreciate the article, and your thoughts. Two big items, in our experience, to add to your list: (1) Initial Cost. Turf is readily available, with a low initial cost (relative to many other ground plane treatments). (2) Maintenance. Again, turf is predictable. All kinds of studies point to turf being a high maintenance cost relative to many other typologies, but: turf maintenance activities are known, predictable, quantifiable, schedulable, and (perhaps most importantly) profitable. We find that most landscape maintenance companies (let alone clients and owners) profess to be able to maintain all types of landscapes, but actual training and execution are lacking.

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