Log in

Search form

LEED v4
Core and Shell
Water Efficiency
Outdoor water use reduction

LEED CREDIT

CS-v4 WEp1: Outdoor water use reduction Required

See all forum discussions about this credit »
View the LEED v4.1 version of this credit »

SPECIAL REPORT

LEEDuser expert

headshot

Dan Ackerstein

Ackerstein Sustainability, LLC
Principal

SPECIAL REPORT

LEEDuser’s viewpoint

Frank advice from LEED experts

LEED is changing all the time, and every project is unique. Even seasoned professionals can miss a critical detail and lose a credit or even a prerequisite at the last minute. Our expert advice guides our LEEDuser Premium members and saves you valuable time.

Credit language

USGBC logo

© Copyright U.S. Green Building Council, Inc. All rights reserved.

Requirements

Reduce outdoor water use through one of the following options. Nonvegetated surfaces, such as permeable or impermeable pavement, should be excluded from landscape area calculations. Athletic fields and playgrounds (if vegetated) and food gardens may be included or excluded at the project team’s discretion.

Option 1. No irrigation required
Show that the landscape does not require a permanent irrigation system beyond a maximum two-year establishment period.

OR

Option 2. Reduced irrigation
Reduce the project’s landscape water requirement by at least 30% from the calculated baseline for the site’s peak watering month. Reductions must be achieved through plant species selection and irrigation system efficiency, as calculated by the Environmental Protection Agency (EPA) WaterSense Water Budget Tool.
SITES-LEED Equivalency

This LEED credit (or a component of this credit) has been established as equivalent to a SITES v2 credit or component. For more information on using the equivalency as a substitution in your LEED or SITES project, see this article and guidance document.

See all forum discussions about this credit »

What does it cost?

Cost estimates for this credit

On each BD+C v4 credit, LEEDuser offers the wisdom of a team of architects, engineers, cost estimators, and LEED experts with hundreds of LEED projects between then. They analyzed the sustainable design strategies associated with each LEED credit, but also to assign actual costs to those strategies.

Our tab contains overall cost guidance, notes on what “soft costs” to expect, and a strategy-by-strategy breakdown of what to consider and what it might cost, in percentage premiums, actual costs, or both.

This information is also available in a full PDF download in The Cost of LEED v4 report.

Learn more about The Cost of LEED v4 »

Frequently asked questions

The EPA WaterSense methodology and calculator allows only certain types of irrigation to be assigned to certain vegetation types. Why is this and won’t it skew results?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

What if we just have a little green area on our rooftop? Is there a minimum amount of landscaped area to earn the prerequisite and credit?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)
See all forum discussions about this credit »

Addenda

4/6/2018 – Updated: 4/6/2018
Reference Guide Correction
Description of change:
under "Step 6. Calculate additional reduction from baseline for smart irrigation controls":

replace the last word in the second sentence, "baseline", with the phrase "landscape water requirement."
Campus Applicable
No
Internationally Applicable:
No
7/1/2016 – Updated: 7/1/2016
Form Update
Description of change:
Revise the examples and calculator to reflect the landscape water baseline, rather than the landscape water allowance (LWA).

Insert new images above Figures 2 and 3 in BD+C and O+M that show the "Part 1 - Baseline & LWA" tab of the .xls Water Budget Tool (https://www3.epa.gov/watersense/excel/water_budget_tool.xlsx).

BD+C prerequisite
Example 1. Livingston, New Jersey
Replace the last paragraph with the following text: "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline amounts to 75%. Since only 30% is required to meet the prerequisite, the project easily achieves compliance."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings from baseline is now 55%, but since only 30% is required, the project still achieves the prerequisite."

BD+C credit
Example 1. Livingston, New Jersey
Replace the paragraph that begins with "The landscape water allowance (30% below baseline minimum) equals..." with the following text: "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline without alternative water sources amounts to 75%. The project achieves the credit and earns 1 point."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings is now 55%, for 1 point."

O+M credit
Example 1. Livingston, New Jersey
Replace all of the text below the Water Budget Tool Table with the following (delete both existing paragraphs): "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline amounts to 75%. The project achieves the credit and earns 2 points."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings is now 55%, for 2 points."

ND credit
Add a new bullet point above the Landscape water allowance line that read: "Landscape water baseline = 746,090 gallons/month"
Campus Applicable
Yes
Internationally Applicable:
Yes
7/1/2016 – Updated: 7/1/2016
Reference Guide Correction
Description of change:
Revise the examples and calculator to reflect the landscape water baseline, rather than the landscape water allowance (LWA).

Insert new images above Figures 2 and 3 in BD+C and O+M that show the "Part 1 - Baseline & LWA" tab of the .xls Water Budget Tool (https://www3.epa.gov/watersense/excel/water_budget_tool.xlsx).

BD+C prerequisite
Example 1. Livingston, New Jersey
Replace the last paragraph with the following text: "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline amounts to 75%. Since only 30% is required to meet the prerequisite, the project easily achieves compliance."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings from baseline is now 55%, but since only 30% is required, the project still achieves the prerequisite."

BD+C credit
Example 1. Livingston, New Jersey
Replace the paragraph that begins with "The landscape water allowance (30% below baseline minimum) equals..." with the following text: "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline without alternative water sources amounts to 75%. The project achieves the credit and earns 1 point."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings is now 55%, for 1 point."

O+M credit
Example 1. Livingston, New Jersey
Replace all of the text below the Water Budget Tool Table with the following (delete both existing paragraphs): "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline amounts to 75%. The project achieves the credit and earns 2 points."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings is now 55%, for 2 points."

ND credit
Add a new bullet point above the Landscape water allowance line that read: "Landscape water baseline = 746,090 gallons/month"
Campus Applicable
Yes
Internationally Applicable:
Yes
4/5/2016 – Updated: 4/7/2016
Form Update
Description of change:
In the Instructions tab, remove all "Pool, spa, or water feature" rows from the tables under the "Assumptions" section. In the Landscape Water Requirement tab, remove "Pool, spa, or water feature" from the drop down list under "Plant Type or Landscape Feature".
Campus Applicable
Yes
Internationally Applicable:
Yes
4/5/2016 – Updated: 4/7/2016
Reference Guide Correction
Description of change:
Align the section with the text in the Prerequisite as follows:
"The World Meteorological Organization website (worldweather.wmo.int) and other sources provide annual precipitation data for many sites. If precipitation data for the project location are unavailable, they must be estimated.

Evapotranspiration data are available through various government and academic sources. The Food and Agriculture Organization of the United Nations (fao.org/nr/water/eto.html) calculates reference evapotranspiration using a variety of algorithms based on monthly average weather data. The month with the largest deficit between reference evapotranspiration and rainfall is the peak watering month.

The international version of the WaterSense Water Budget Tool can be found on the USGBC website under this credit’s resources section (See International Tips, Canada)."
Campus Applicable
Yes
Internationally Applicable:
Yes
10/1/2015 – Updated: 10/1/2015
Reference Guide Correction
Description of change:
Revise the text below Figure 2 (that begins with "The landscape water allowance...") to read:
"The landscape water allowance (30% below baseline minimum) equals 43,980 gallons a month. The landscape water requirement for this design in this location is 15,939 gallons a month. The total savings without alternative water sources equals 75%. The project achieves the credit and earns 1 point.

The team has determined that rainwater harvested from the building’s roof will supply all the project’s outdoor water needs. Given the average monthly rainfall in this location and the roof’s area, the average monthly rainwater available for harvesting is 18,360 gallons per month:

Equation 1 in Step-by-step is used to calculate the amount of rainwater harvested from the roof:
Gallons per 1 inch of rain = 9,000 ft2 x 0.6
Gallons per 1 inch of rain = 5,400 gal

Equation 2 in Step-by-step is then used to determine the monthly harvested rainwater volume:
Amount available = 5,400 gal/in x 3.4 in/mo
Amount available = 18,360 gal/mo

The team ensures that the rainwater needed in the peak watering month can be stored on-site and installs a rainwater cistern capable of holding 20,000 gallons of rainwater for irrigation.

Equation 3 in Step-by-step is used to determine the adjusted landscape water requirement:
Adjusted LWR = 15,939 gal/mo - 18,360 gal/mo
Adjusted LWR = -2,421 gal/mo

The total water requirement is 15,939 gallons a month. Minus the 18,360 gallons a month available for harvesting, the project uses –2,421 gallons a month (i.e., it has a rainwater surplus). The total savings is 100%, for 2 points."
Campus Applicable
Yes
Internationally Applicable:
Yes
10/1/2014 – Updated: 2/14/2015
Form Update
Description of change:
Initial release of the Outdoor Water Use Reduction Calculator (international version of EPA's WaterSense calculator with SI units).
Form changes include adding references to the new Outdoor Water Use Reduction Calculator and adding SI units to the additional reductions section.
Campus Applicable
No
Internationally Applicable:
Yes
1/1/2015 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace:
An Excel version of the WaterSense Water Budget Tool can be found under the Resources tab for this credit, at usgbc.org/credits.
Project teams outside the U.S. must complete the tool using IP rather than SI units. Use the conversion calculator found under the Resources tab.

With:
Projects outside the U.S: use the non-U.S. water budget calculator, which can be found on usgbc.org. Projects must provide rainfall and evapotranspiration data for their location. This calculator uses SI units.
Campus Applicable
No
Internationally Applicable:
Yes
See all forum discussions about this credit »

Documentation toolkit

The motherlode of cheat sheets

LEEDuser’s Documentation Toolkit is loaded with calculators to help assess credit compliance, tracking spreadsheets for materials, sample templates to help guide your narratives and LEED Online submissions, and examples of actual submissions from certified LEED projects for you to check your work against. To get your plaque, start with the right toolkit.

LEEDuser expert

headshot

Dan Ackerstein

Ackerstein Sustainability, LLC
Principal

Get the inside scoop

Our editors have written a detailed analysis of nearly every LEED credit, and LEEDuser premium members get full access. We’ll tell you whether the credit is easy to accomplish or better left alone, and we provide insider tips on how to document it successfully.

USGBC logo

© Copyright U.S. Green Building Council, Inc. All rights reserved.

Requirements

Reduce outdoor water use through one of the following options. Nonvegetated surfaces, such as permeable or impermeable pavement, should be excluded from landscape area calculations. Athletic fields and playgrounds (if vegetated) and food gardens may be included or excluded at the project team’s discretion.

Option 1. No irrigation required
Show that the landscape does not require a permanent irrigation system beyond a maximum two-year establishment period.

OR

Option 2. Reduced irrigation
Reduce the project’s landscape water requirement by at least 30% from the calculated baseline for the site’s peak watering month. Reductions must be achieved through plant species selection and irrigation system efficiency, as calculated by the Environmental Protection Agency (EPA) WaterSense Water Budget Tool.
SITES-LEED Equivalency

This LEED credit (or a component of this credit) has been established as equivalent to a SITES v2 credit or component. For more information on using the equivalency as a substitution in your LEED or SITES project, see this article and guidance document.

Cost estimates for this credit

On each BD+C v4 credit, LEEDuser offers the wisdom of a team of architects, engineers, cost estimators, and LEED experts with hundreds of LEED projects between then. They analyzed the sustainable design strategies associated with each LEED credit, but also to assign actual costs to those strategies.

Our tab contains overall cost guidance, notes on what “soft costs” to expect, and a strategy-by-strategy breakdown of what to consider and what it might cost, in percentage premiums, actual costs, or both.

This information is also available in a full PDF download in The Cost of LEED v4 report.

Learn more about The Cost of LEED v4 »

In the end, LEED is all about documentation. LEEDuser’s Documentation Toolkit, for premium members only, saves you time and helps you avoid mistakes with:

  • Calculators to help assess credit compliance.
  • Tracking spreadsheets for materials purchases.
  • Spreadsheets and forms to give to subs and other team members.
  • Guidance documents on arcane LEED issues.
  • Sample templates to help guide your narratives and LEED Online submissions.
  • Examples of actual submissions from certified LEED projects.

The EPA WaterSense methodology and calculator allows only certain types of irrigation to be assigned to certain vegetation types. Why is this and won’t it skew results?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

What if we just have a little green area on our rooftop? Is there a minimum amount of landscaped area to earn the prerequisite and credit?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)
4/6/2018 – Updated: 4/6/2018
Reference Guide Correction
Description of change:
under "Step 6. Calculate additional reduction from baseline for smart irrigation controls":

replace the last word in the second sentence, "baseline", with the phrase "landscape water requirement."
Campus Applicable
No
Internationally Applicable:
No
7/1/2016 – Updated: 7/1/2016
Form Update
Description of change:
Revise the examples and calculator to reflect the landscape water baseline, rather than the landscape water allowance (LWA).

Insert new images above Figures 2 and 3 in BD+C and O+M that show the "Part 1 - Baseline & LWA" tab of the .xls Water Budget Tool (https://www3.epa.gov/watersense/excel/water_budget_tool.xlsx).

BD+C prerequisite
Example 1. Livingston, New Jersey
Replace the last paragraph with the following text: "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline amounts to 75%. Since only 30% is required to meet the prerequisite, the project easily achieves compliance."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings from baseline is now 55%, but since only 30% is required, the project still achieves the prerequisite."

BD+C credit
Example 1. Livingston, New Jersey
Replace the paragraph that begins with "The landscape water allowance (30% below baseline minimum) equals..." with the following text: "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline without alternative water sources amounts to 75%. The project achieves the credit and earns 1 point."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings is now 55%, for 1 point."

O+M credit
Example 1. Livingston, New Jersey
Replace all of the text below the Water Budget Tool Table with the following (delete both existing paragraphs): "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline amounts to 75%. The project achieves the credit and earns 2 points."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings is now 55%, for 2 points."

ND credit
Add a new bullet point above the Landscape water allowance line that read: "Landscape water baseline = 746,090 gallons/month"
Campus Applicable
Yes
Internationally Applicable:
Yes
7/1/2016 – Updated: 7/1/2016
Reference Guide Correction
Description of change:
Revise the examples and calculator to reflect the landscape water baseline, rather than the landscape water allowance (LWA).

Insert new images above Figures 2 and 3 in BD+C and O+M that show the "Part 1 - Baseline & LWA" tab of the .xls Water Budget Tool (https://www3.epa.gov/watersense/excel/water_budget_tool.xlsx).

BD+C prerequisite
Example 1. Livingston, New Jersey
Replace the last paragraph with the following text: "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline amounts to 75%. Since only 30% is required to meet the prerequisite, the project easily achieves compliance."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings from baseline is now 55%, but since only 30% is required, the project still achieves the prerequisite."

BD+C credit
Example 1. Livingston, New Jersey
Replace the paragraph that begins with "The landscape water allowance (30% below baseline minimum) equals..." with the following text: "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline without alternative water sources amounts to 75%. The project achieves the credit and earns 1 point."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings is now 55%, for 1 point."

O+M credit
Example 1. Livingston, New Jersey
Replace all of the text below the Water Budget Tool Table with the following (delete both existing paragraphs): "The landscape water allowance equals 43,980 gallons/month. The landscape water baseline equals 62,829 gallons/month. The LWR for this design in this location is 15,939 gallons/month. The total savings from the baseline amounts to 75%. The project achieves the credit and earns 2 points."

Example 2. Palo Alto, California
Replace the last paragraph with the following text: "With a total landscape area of 16,000 square feet—10,000 square feet of groundcover (low water need, native species, drip irrigation) and 6,000 square feet of trees (medium water need, drip irrigation)—the tool now calculates a landscape water allowance of 41,886 gallons/month, and a landscape water baseline of 59,837 gallons/month. Compared with the New Jersey example above, the landscape water requirement for this design has increased to 26,713 gallons/month. The total savings is now 55%, for 2 points."

ND credit
Add a new bullet point above the Landscape water allowance line that read: "Landscape water baseline = 746,090 gallons/month"
Campus Applicable
Yes
Internationally Applicable:
Yes
4/5/2016 – Updated: 4/7/2016
Form Update
Description of change:
In the Instructions tab, remove all "Pool, spa, or water feature" rows from the tables under the "Assumptions" section. In the Landscape Water Requirement tab, remove "Pool, spa, or water feature" from the drop down list under "Plant Type or Landscape Feature".
Campus Applicable
Yes
Internationally Applicable:
Yes
4/5/2016 – Updated: 4/7/2016
Reference Guide Correction
Description of change:
Align the section with the text in the Prerequisite as follows:
"The World Meteorological Organization website (worldweather.wmo.int) and other sources provide annual precipitation data for many sites. If precipitation data for the project location are unavailable, they must be estimated.

Evapotranspiration data are available through various government and academic sources. The Food and Agriculture Organization of the United Nations (fao.org/nr/water/eto.html) calculates reference evapotranspiration using a variety of algorithms based on monthly average weather data. The month with the largest deficit between reference evapotranspiration and rainfall is the peak watering month.

The international version of the WaterSense Water Budget Tool can be found on the USGBC website under this credit’s resources section (See International Tips, Canada)."
Campus Applicable
Yes
Internationally Applicable:
Yes
10/1/2015 – Updated: 10/1/2015
Reference Guide Correction
Description of change:
Revise the text below Figure 2 (that begins with "The landscape water allowance...") to read:
"The landscape water allowance (30% below baseline minimum) equals 43,980 gallons a month. The landscape water requirement for this design in this location is 15,939 gallons a month. The total savings without alternative water sources equals 75%. The project achieves the credit and earns 1 point.

The team has determined that rainwater harvested from the building’s roof will supply all the project’s outdoor water needs. Given the average monthly rainfall in this location and the roof’s area, the average monthly rainwater available for harvesting is 18,360 gallons per month:

Equation 1 in Step-by-step is used to calculate the amount of rainwater harvested from the roof:
Gallons per 1 inch of rain = 9,000 ft2 x 0.6
Gallons per 1 inch of rain = 5,400 gal

Equation 2 in Step-by-step is then used to determine the monthly harvested rainwater volume:
Amount available = 5,400 gal/in x 3.4 in/mo
Amount available = 18,360 gal/mo

The team ensures that the rainwater needed in the peak watering month can be stored on-site and installs a rainwater cistern capable of holding 20,000 gallons of rainwater for irrigation.

Equation 3 in Step-by-step is used to determine the adjusted landscape water requirement:
Adjusted LWR = 15,939 gal/mo - 18,360 gal/mo
Adjusted LWR = -2,421 gal/mo

The total water requirement is 15,939 gallons a month. Minus the 18,360 gallons a month available for harvesting, the project uses –2,421 gallons a month (i.e., it has a rainwater surplus). The total savings is 100%, for 2 points."
Campus Applicable
Yes
Internationally Applicable:
Yes
10/1/2014 – Updated: 2/14/2015
Form Update
Description of change:
Initial release of the Outdoor Water Use Reduction Calculator (international version of EPA's WaterSense calculator with SI units).
Form changes include adding references to the new Outdoor Water Use Reduction Calculator and adding SI units to the additional reductions section.
Campus Applicable
No
Internationally Applicable:
Yes
1/1/2015 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace:
An Excel version of the WaterSense Water Budget Tool can be found under the Resources tab for this credit, at usgbc.org/credits.
Project teams outside the U.S. must complete the tool using IP rather than SI units. Use the conversion calculator found under the Resources tab.

With:
Projects outside the U.S: use the non-U.S. water budget calculator, which can be found on usgbc.org. Projects must provide rainfall and evapotranspiration data for their location. This calculator uses SI units.
Campus Applicable
No
Internationally Applicable:
Yes

LEEDuser expert

headshot

Dan Ackerstein

Ackerstein Sustainability, LLC
Principal

See all LEEDuser forum discussions about this credit » Subscribe to new discussions about CS-v4 WEp1 View the LEED v4.1 version of this credit