How much water does your landscape really need?

New summer water use reports help customers understand how efficient they are with outdoor watering.

July 11, 2019 | By: Jessica Kirk

Mary, who was sometimes quite contrary, often wondered how her garden grew.

There were some silver bells and cockleshells, but we’re pretty sure there was water too.

But Mary probably wondered, how much water did her garden truly need to grow?

Denver Water has an answer for that.

Bluegrass lawn watering
Experts say only 12 gallons per square foot is required to have a healthy, mixed-use landscape that includes alternative landscape types like xeric or native plants and grass, vegetable gardens and bluegrass turf. Photo credit: Denver Water.


In preparing its Water Efficiency Plan, Denver Water worked with a group of community stakeholders, including water and landscape professionals, to review water requirements for a variety of landscape types like xeric, bluegrass, rock and mulch.

The information collected from these experts helped Denver Water determine that 12 gallons of water per square foot of mixed-use landscape per year is a good goal for efficient outdoor water use. Mixed-use landscapes include alternative landscape types like xeric or native plants and grass, vegetable gardens and bluegrass turf.

In June, Denver Water began emailing personalized water use reports to help customers understand how their individual water use during the outdoor watering season compares to the goal of 12 gallons of water per square foot of landscape per year.

Sample of an outdoor water use report emailed to Denver Water customers this summer. Photo credit: Denver Water.


How does Denver Water determine individual efficiency?

To calculate an individual customer’s water efficiency target, Denver Water created a monthly water budget for each household.

To create a customer’s monthly water budget, the utility started by using 12 gallons per square foot of landscape per year, then added in the customer’s average winter consumption from their bill. Each customer’s average winter consumption is considered to be indoor water use. The average winter consumption is shown on customer bills dated January, February and March.

For example, the outdoor water budget for a home with 3,000 square feet of landscape is 36,000 gallons per year.

3,000 square feet of landscape × 12 gallons = 36,000 gallons per year

That’s just for outdoor water use.

That figure for outdoor water use is then distributed throughout the year based on the seasonal plant needs. Plants need more water in the summer when it’s hot and dry compared to the spring or fall, when it’s cooler.

When Denver Water added in the indoor water use, shown as the average winter consumption number on the bills dated January, February and March. In the example (below), the customer’s average winter consumption, considered to be their indoor water use, is 4,000 gallons of water per month.

Adding those two figures together, the outdoor water use and the indoor use, gives the customer their personal monthly efficiency target.

In the example of the customer with 3,000 square feet of landscape, the monthly efficiency target varies month-to-month, depending on the season. It looks like this:

The personal water use target is how much water the customer needs for efficient indoor and outdoor water use.

The report shows the efficiency target as a line on a graph and shows how much water the customer has used each month and how that compares to their target.

If you are a Denver Water customer who is interested in receiving these reports, please log in to Denver Water Online and add your email address under the Account Maintenance tab of the self-service portal.

You can also call Customer Care at 303-893-2444 (7:30 a.m.–5:30 p.m., Monday-Friday) and update your contact information to include an email address.

2 thoughts on “How much water does your landscape really need?”

    1. In 2016, Denver Water convened a Water Efficiency Working Group (WEWG) to define efficient use. Members of WEWG represented Western Resource Advocates, Colorado River District, University of Denver, Associated Landscape Contractors of Colorado (ALCC), City of Lakewood, Denver Public Schools, City and County of Denver, ProLogis, Denver City Council, Valdez Public Affairs, and Platte Canyon Water and Sanitation.

      The WEWG determined that the water efficiency benchmark for Single Family Residential Outdoor customer use should be 12 gallons per square foot (GPSF) of pervious area based on typical landscape made up of 18% non-irrigated; 29% alternative landscaping and 53% bluegrass turf.

      The WEWG spent the majority of its time discussing outdoor water use efficiency benchmarking and through consensus determined that 12 gallons per square foot (GSPF) is an appropriate benchmark. Denver Water presented its data on how much water customers currently use per square foot and the average customer already uses 12 GPSF. It should be noted that there was strong debate in the Work Group about whether a range was appropriate, and whether the 12 GPSF was enough to maintain healthy turf grass.

      In the end, the Work Group established that this voluntary benchmark was appropriate for landscapes that include a variety of both non-irrigated, alternative landscape types (such as xeriscape or native), and bluegrass turf. It was also established that this benchmark requires attention to landscape health and aesthetic value.

      The Working Group’s recommendations have been set based on currently achievable levels of use that maintain livability. Residential indoor use of 40 gallons per resident per day is achievable with current use habits and readily available water efficient plumbing fixtures; In fact, 49 percent of our customers have already done so. Attaining a 12 gallons-per-square-foot benchmark for residential landscapes is also attainable—in fact more than half of our customers have already achieved this benchmark. But moving customers toward the benchmark means a greater focus on changing landscapes, amending soil and paying attention to irrigation practices so water efficiency is achieved while balancing healthy trees and landscapes.

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