Irrigation Schedule & Tips
Tucson Water proposes
a balanced weekly irrigation schedule
to help customers conserve water while maintaining healthy landscapes.
| Sunday | Homes with ODD number addresses |
| Monday | Commercial and Industrial ALL addresses |
| Tuesday | Homes with EVEN number addresses |
| Wednesday | Beat the Peak: NO IRRIGATION |
| Thursday | Homes with ODD number addresses |
| Friday | Commercial and Industrial ALL addresses |
| Saturday | Homes with EVEN number addresses |
by Tucson Water Conservation Program Manager Fernando Molina
Tucson Water is providing guidelines to the public for scheduling irrigation of landscapes. Customers are being asked to implement the schedule as soon as possible, as the guidelines are designed to help control irrigation water use while at the same time encourage strong, healthy growth in landscapes. “These guidelines are based on the principle of providing deep, infrequent applications of water to plants,” says former Tucson Water Director David Modeer. “It is also a way for everyone to participate to help maintain a safe level of water in our reservoir system during the summer months.”
The schedule provides residential and commercial customers clear guidelines for what days to water on. The last digit of the street address determines residential irrigation days. Addresses ending in odd numbers are being asked to water on Sundays and Thursdays. Addresses ending in even numbers are being asked to water only on Saturdays and Tuesdays. Commercial properties are being asked to water only on Mondays and Fridays. According to former Director Modeer, “This schedule allows all residences to irrigate at least one day during the weekend, when residents are more likely to be around to observe the irrigation system and plants.” Commercial customers typically have landscape services available during the weekdays to observe the plants and irrigation system.
Landscape irrigation contributes significantly to water demand in our community. This demand for water to maintain our landscapes can cause significant increases in water use during extended hot, dry periods such as we have experienced so far this year. The groundwater wells operated by Tucson Water can produce approximately 145 million gallons of water per day, yet planners are currently projecting a peak demand day of 155 million gallons per day. 240 million gallons of groundwater stored in the extensive reservoir system act as a buffer when demand exceeds supply, yet can decline to dangerously low levels if water use remains unchecked.
“Poor irrigation scheduling practices are one of the problems we regularly see in commercial and residential landscapes,” according to Fernando Molina, Conservation Manager for Tucson Water. Plants that get watered for short periods of time every other day or more frequently often develop very shallow root systems. As the weather warms up, the soils dry out quicker, requiring more frequent applications of water to keep the plant alive. A better strategy, says Molina, is to apply more water but wait longer in between irrigations. “This encourages the roots of plants to grow deeper into the soil where evaporation is less.” Practicing deep-irrigation scheduling may require you to run your irrigation system for several hours to ensure that the water is penetrating the soil to the proper root depth. Irrigation run times of 4-6 hours are not uncommon. It’s also a good idea to allow the soil around the plant to dry out some before more water is applied. Using this method to irrigate results in healthier plants, with deeper root zones that will better withstand the hot dry summer months of the Sonoran Desert.
Molina cautions that some care must be taken when changing irrigation scheduling methods. Plants that are accustomed to shallow, frequent watering must be changed to less frequent, deep waterings slowly to allow for better root growth so as not to shock or kill the plant. A soil probe can be used to measure how deep the irrigation water has penetrated the soil. The irrigation system itself may need to be modified to ensure an even distribution of water. For example, dry spots appearing between sprinklers on grass may be indicative of poor spacing between heads, sunken heads, or low pressure. The desire to have no dry spots often results in longer irrigations, but the real solution is to improve the irrigation system by adding or moving sprinkler heads, or adjusting pressure.
Finally, the schedule only provides a basis from which to begin with under normal conditions. Depending on your specific conditions, you may need to add a third day to the schedule and work over a period of several weeks to allow your plants to slowly develop deeper root systems. Larger trees and shrubs that are established may also need less frequent waterings. Plants in containers will also require more frequent waterings, perhaps even daily. However, it is important to remember that if a water emergency is declared, this schedule may become mandatory for the duration of the emergency.
Tucson Water is promoting the schedule as a means of educating the public about proper irrigation scheduling practices. Efficient irrigation scheduling practices are often hampered due to poor irrigation system performance. The recommended watering schedule is consistent with Tucson Water Landscape Water Conservation programming efforts focusing on better irrigation system design and maintenance practices. Good design and maintenance have been found to help ensure maximum conservation benefits through scheduling practices. The irrigation schedule has been researched, tested, and developed with input from various landscape industry professionals in Tucson.
However, Tucson Water officials also want the public to be aware that the schedule may become mandatory if a Water Emergency is declared. It also would be issued as an advisory practice should reservoir levels drop at a rate that would cause concern. The schedule does not apply to landscapes irrigated by reclaimed water, nor is it generally advisable for plants growing in containers.
Water Smart Irrigation Tips
Reach Your Roots
Plants have different rooting depths and watering requirements. In general, annuals and grasses have roots extending down up to 12 inches, shrubs 24 inches, and trees 36 inches. Any water applied beyond the root zones is water the plant can’t use. Most desert-adapted plants require less frequent watering than non-desert species.
A soil probe is a metal rod, such as a piece of rebar, or a long handled screwdriver, used to measure how deep the water has penetrated the soil after an irrigation. Simply push the probe, metal rod, or longer handled screwdriver into the ground after you irrigate. It will easily push through wet soil and stop as dry soil is encountered. This provides you with a simple method to determine if your length of irrigation is sufficient. Periodically check the soil with the probe to determine when it is time to irrigate again. Once the soil is dried out, the probe will become more difficult to push into the ground.
Wake Up and Water
Cooler temperatures in the earliest part of the morning help to reduce evaporation losses from various irrigation systems. This is also usually the least windy time of day, so sprinkler systems will spray water more efficiently.
Watch Your Watering
Leaks, missing drip emitters or broken sprinkler heads can seriously affect the performance of your irrigation system. Besides allowing water to be wasted, these problems can result in plants not receiving sufficient moisture deeper in the root zone. Also, since most systems run early in the morning, or at other times when no one is around to look for leaks or other problems, it is a good idea to periodically turn the irrigation system on and observe for problems.
Reuse the Rain
There are several simple things one can do to take advantage of rainfall to supplement your landscape irrigation. Building berms around plants, diverting runoff from rooftops and walkways to plants, and using containers to store rainwater.
Make a Cool, Cool Change
The summer heat can make it tough on new plants. New landscape plantings require more frequent waterings to establish strong root systems. If you are planning to change your landscaping, do the work in the cooler months of the year. Your new plants will do better and you’ll need less water to get them established.
Turn On to a Timer
An irrigation timer can help you save water in your landscape. Establish an appropriate irrigation schedule for your site conditions, and learn how to set the schedule into your timer. Also, don’t forget to make periodic adjustments to account for changing water requirements as the seasons change.
For more information and helpful conservation tips, call (502) 791-4566.
