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.

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 begins 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.

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, 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.