Water-efficient Landscaping
In many areas of the country, water use for irrigation exceeds indoor consumption, averaging more than 50% of total residential consumption in the U.S. So, while installing water-efficient fixtures inside a home is an important step toward water efficiency, addressing outside use should be at the top of your list, especially if your projects are in drought-prone locations.
But where outfitting a home with efficient bath fixtures is pretty straightforward, designing and installing water-efficient landscaping and irrigation can be complex. Designing a landscape to conserve water—xeriscaping—requires choosing plants that will thrive in your region and your project’s particular microclimate; limiting the turf areas; making sure the soil on site will promote water absorption and deep root growth; and, if irrigation is installed, using an efficient system.
Initial Steps
First, do no harm. Preserving soil quality is important for water efficiency. Also, commit to losing some lawn. Some local and regional governments offer financial incentives to reduce the size of irrigated lawns. The EPA’s Water Sense program for single-family homes recommends limiting turf area to a maximum of 40% of the site, balancing the rest of the landscaping with drought-resistant plantings and permeable surfaces. Water Sense also recommends treating slopes in excess of 4:1 with vegetation that will help keep stormwater from running off the site, and covering exposed soil areas in planting beds with a 2- to 3-inch layer of mulch.
Water Wisely:
Irrigation systems should include separate zones to accommodate different watering requirements, drip irrigation for plant beds, and rotating sprinkler heads for turf areas that should be laid out to avoid duplicate coverage and watering paved areas and buildings. Surface runoff can be reduced by keeping the precipitation rate from sprinklers below the soil’s infiltration rate, and establishing different zones for the tops and toes of slopes.
Overwatering is a major problem, The Irrigation Association’s (IA) Smart Water Application Technologies (SWAT) program, a partnership between water utilities and industry representatives, promotes the use of “smart” irrigation control technology that uses climate, site, horticultural, and/or soil moisture information to adjust irrigation to conditions on the site.
Case studies carried out by the IA suggest that systems that use smart controllers can reduce water use by 20% to 40% compared to timer-based systems.
Let it Rain:
Harvesting, or simply redirecting water from downspouts to plants (along with utilizing porous materials for non-planted areas) keeps runoff out of the sewer system, easing stress on infrastructure while allowing more water to percolate back into the groundwater. Water from a small roof area can simply be sent to a lawn or planting bed; larger amounts can supply a specially designed rain garden that is graded to collect water, filled with well-drained soil, and planted with species that can tolerate inundation as well as drier periods in between storms. Some local governments offer design assistance or even grants to expand the use of rain gardens and other techniques that treat rainwater as a resource, not a waste product.
