“Water-Thrifty” Sustainable Landscapes

Watering can be the costliest part of maintaining a landscaped property, especially in areas prone to drought, like the western United States. Find out how you can conserve both water and your budget – and help protect your local environment.

Twelve Water-Thrifty Tips

There are many strategies you can use to conserve, redistribute, and reuse water.

1. Irrigate only when plants need water and choose the best time of day.

How often you water depends on a number of factors, including soil and vegetation type, whether or not the plants are established, the season, and weather conditions.

Sunny or windy conditions increase evaporation and the loss of water. The most favorable conditions for irrigation are typically in the early morning hours. Two relatively simple tools can help gardeners determine when to water:

• The simplest and most inexpensive is a rain gauge to measure weekly rainfall.
• Soil moisture probes are also commercially available and can provide accurate data.

Rain gauges and soil moisture probes should be used in conjunction with basic knowledge about how much water various parts of the landscape require. For example, vegetables generally need more than established woody plants. And even edible plants require less water when it is overcast and relatively cool than when it is sunny and hot.

2. Water by hand.

According to an American Water Works Association Research Foundation study, manual watering with a hand-held hose conserves more water than other irrigation methods.

If in-ground systems are required, consider a drip system. These use the least amount of any automatic system—but still 16 percent more than watering by hand.

In-ground spray systems used 35 percent more water than hand watering, and an automatic spray system used 47 percent more.

3. Use the latest irrigation technology.

To maximize efficiency, install climate-based controllers such as sensors that prevent the irrigation system from turning on during or immediately after rainfall. Even better are sensors that activate irrigation only when soil moisture drops below a predetermined level. So-called “smart” or weather-based irrigation controllers take into account a range of factors including temperature, rainfall, humidity, solar radiation, and soil moisture levels to determine when supplemental water is necessary.

As with all technologies, water-conserving irrigation systems and devices must be installed and operated correctly in order to be truly effective.

4. Keep an eye on your irrigation system.

Regularly check irrigation equipment for leaks or breaks. Adjust irrigation equipment and schedules to address changes in the landscape and seasons. Monitoring the amount of water used by the irrigation system will help flag any leaks or breaks within the system and will encourage conservation efforts.

5. Use alternatives to municipal drinking water for irrigation.

With a little ingenuity, gardeners can use non-potable water from a variety of indoor and outdoor sources to irrigate their garden. Water that is non-potable is not safe for humans to drink but can be a great resource for vegetation. Such alternative water resources as rainwater runoff, air-conditioner condensate and greywater are typically considered waste products in conventional landscapes and quickly removed from the site. Sustainable landscapes capture this water and use it to benefit the garden. In doing so, downstream aquatic ecosystems are protected from pollutants commonly carried in stormwater. Further, the volume of water going to storm sewer systems is reduced, lessening the likelihood of flooding and combined sewer overflows.

6. Collect rainwater.

Rainwater collection has been used for centuries to support households and grow beautiful, productive gardens. The practice typically falls into two categories, passive and active.

Passive Rainwater Harvesting

Passive rainwater harvesting diverts water overland to vegetated areas for immediate use. Roads, driveways, and sidewalks are designed to direct water to vegetated areas instead of storm drains. Design features such as shallow bioswales or terraces can be integrated into the landscape and used to slowly convey and disperse the water throughout the garden.

Active Rainwater Harvesting

Active rainwater harvesting captures water in a barrel, cistern, or tank where it is held for reuse. The containers are typically manufactured in a variety of shapes and sizes and connected to the downspouts of a roof gutter system.

Rain barrels generally hold around 50 gallons and come with a screened cover and an overflow spout.

Cisterns are used to store larger volumes of water and may be buried below ground or integrated into the landscape or building design as a freestanding structure.

Active rainwater harvesting is prohibited in some areas. Local water laws should be understood prior to designing a rainwater collection system.

7. Use air conditioner condensate.

Condensate is produced when warm, moisture-laden air passes over the coils of an air-conditioning system. Collecting condensate is an attractive irrigation option because, unlike rain, which is sporadic and unpredictable, condensate is produced regularly during the hottest months when the need for irrigation is greatest.

The average single-family home produces 5 to 10 gallons of condensate per day. Condensate recovery systems are best suited to hot and humid climates.

8. Collect greywater.

A variety of appliances and fixtures produce used water called greywater. An estimated 50 to 80 percent of residential “wastewater” is dish, shower, sink, and laundry water. Many people find greywater an attractive option because it provides a steady water source year-round and saves potable water resources. Greywater can be safely used to grow beautiful gardens. However, due to the soaps, detergents, skins cells, and other organic substances commonly found in greywater, direct human contact should be avoided.

Landscape characteristics that may prevent the use of greywater include:

• Areas prone to water ponding or flooding
• High water tables
• Shallow soils
• Steep slopes that may lead to runoff or seepage

Note: Be sure to check your local rules and regulations regarding graywater collection and usage.\

9. Use plants adapted to local rainfall patterns.

Growing plants adapted to particular site conditions is one of the basic principles of sustainable gardening.

Tips include:

• Lawn size and turf type can have a huge impact on the amount of irrigation a landscape requires.
• Consider the function of the lawn and how much area is actually required to support its use. Look for ways to minimize unnecessary lawn.
• Choose grass species that require minimal irrigation. Consider mixing different types of grasses to create a more disease-resistant lawn.

Preserve as many well-established trees and shrubs as possible. Established vegetation generally requires less water than newly planted specimens that have not yet developed deep root systems. Favor plants native to the region that are adapted to the local climate and well suited to the growing conditions of a site.

To speed establishment and minimize water use, plant at the recommended time of the year for each particular species.

10. Limit exposure to pesticides.

When most people think of pesticide use, they think of agricultural land. But pesticides are typically applied at much higher rates to residential landscapes than to farms — 20 times higher, according to the U.S. Environmental Protection Agency (EPA).

The enormous quantity of pesticides used in home landscapes raises a number of health and environmental concerns, starting with the potential for accidental poisonings of humans and pets. Although pesticides and their use are regulated by the EPA, the uncertainty over the long-term effects of exposure to even low levels led the American Medical Association to recommend that we limit exposure to these chemicals and use safer alternatives.

Overuse of pesticides is contributing to the chemical load not just in our bodies, but in the environment at large. It’s estimated that 5 percent or less of the insecticides and herbicides we spray ends up on the targeted pest. The rest ends up on non-target plants, in the soil, and in the air via drift. It can also land on nearby people or pets.

Pesticides in runoff find their way into drinking water supplies and local waterways. In fact, pesticide pollution was found in every stream and over 90 percent of the wells sampled in a study by the U.S. Geological Survey.

11. Protect and restore vegetated buffers.

In undisturbed natural areas, waterways and wetlands are typically protected by adjacent vegetation. Grassland, woodland, and wetland plant communities naturally infiltrate and cleanse stormwater. Buffers along waterways and wetlands can also improve wildlife and fish habitat by providing food, shelter, and shade. When vegetation is replaced by impervious surfaces, stormwater runoff volumes increase. Stormwater often carries pollutants including nutrients from fertilizers, pet wastes, and sediment into natural water bodies. The pollutants reduce the overall water quality and negatively affect wildlife habitat. In residential areas, turf grass often extends all the way down to the water, polluting it with fertilizers and pesticides routinely used in lawn care.

In developed areas, vegetated buffers can fulfill the same important ecological functions as undisturbed waterside vegetation. As the name suggests, these are thickly vegetated strips of land that protect waterways and wetlands from polluted runoff and erosion. They also provide habitat for a variety of wildlife year round, including “stopover habitat” for migrating birds in spring and fall.

Research shows that as the width of a vegetated buffer increases, its environmental benefits also grow. Buffers less than 50 feet wide offer minimal protection, while those 200 to 300 feet wide improve water quality and protect aquatic habitats. Vegetated buffers more than 300 feet wide can function as wildlife corridors and even harbor imperiled and sensitive species.

To take a deep dive into green infrastructure and rainwater harvesting, check out the Landscape for Life Online Training:

• AGLL 1006 Green Infrastructure: Rainwater Harvesting and Gardening.

12. Create a rain garden or bioswale.

Bioswales and rain gardens offer another creative way to conserve and redistribute rainwater. These features vary in size and design but are typically located in low areas, where water can naturally soak into the soil.