Landscape Irrigation Education

 

Most Recent Event:

Presentation by Charles Swanson, M. Agr., CAIS, TAMU Agrilife Extension Service

Wellborn Community Center, April 20, 2024

 

 

On April 20, 2024, an educational seminar on landscape irrigation was presented by TAMU Agrilife Extension Specialist and Coordinator of the TAMU School of Irrigation, Charles Swanson.  The event was the first in what is planned to be a series of educational events to inform WSUD customers of landscape irrigation best practices and common problems with home irrigation systems.  Below is a summary of the information that was presented.  A handout from the event can be downloaded at the bottom of this page.  A recording of the event will be available soon.

Relevant Links:

Texas ET Network: texasET.tamu.edu

Watermyyard App: watermyyard.org

 

How much water does my lawn need? (presented by Charles Swanson, summarized here by staff)

(1) The water needs of your plants will change throughout the year – run times should change accordingly.

  1. Lowest needs in the Winter
  2. Gradually increases during Spring
  3. Peaks in Summer
  4. Gradually declines during Fall

(2) Water needs vary throughout the state, based on local climate conditions and rainfall.

  1. Consult irrigation services that use local weather data such as Watermyyard (www.watermyyard.org) or the Texas ET Network (texaset.tamu.edu)

(3) Irrigation should be used to supplement rainfall

  1. For example: If your landscape needs 0.75 inches per week, and it rains 0.25 inches during the week, you only need to irrigate 0.5 inches per week.

(4) The real problem is that there is no “inches” setting on your sprinkler controller. To determine how many inches will be applied during a run time, you will need to know how much water the sprinkler heads in that zone put out.

  1. Consult manufacturers specifications
  2. Perform Catch Can test
    1. Place graduated “catch cans” (measuring cups) in your landscape and run your system for ten minutes.
    2. The depth of water in the can will be the amount of water in inches that your sprinkler can apply in 10 minutes.  Multiply that by 6 to get the amount of water that can be applied in one hour.  This will be your application rate in inches per hour.

(5) Your sprinkler run time will be the amount of time your sprinklers need to run at the measured rate to apply the desired amount of water.

  1. Continuing the example above, if you need to irrigate 0.5 inches, and you know your sprinklers apply 2 inches per hour, then you only need a 15 minute run time.

(6) Take the time to run your system briefly during the day when you can watch it. Keep an eye on the ground under your landscaping as your system runs. Does water start to stack up and run off halfway through the run time?  Your soil may take water up slower than your sprinkler puts out.

  1. Determine exactly how long the sprinkler can run before you start to see runoff.
  2. Cut your run time down so that the zone turns off before runoff starts.
  3. Add another run time of the same length that starts about 45 minutes after the first one ends.
  4. To continue the example again, you know you need a 15 minute run time to apply the 0.5 inches, but you have observed previously that water begins to run-off after 7 minutes of sprinkling.  All you need to do is set your run time for 7 minutes and set a second run time to start 52 minutes later.  The sprinkler will run for 7 minutes and turn off, a 45 minute rest period will allow the water you have applied to infiltrate into the ground, and then the sprinkler will come on again for 7 minutes to apply the rest of the 0.5 inches. (This practice is known as 'cycle and soak')

 

Top 10 Landscape Irrigation Problems (Presented by Charles Swanson, summarized here by staff)

(10) Drip irrigation must be properly maintained

  1. Drip systems can save water if properly designed and installed, however:
  2. Fittings can be susceptible to leaks, and soft tubing is vulnerable to tears and punctures.
  3. Leaks tend to occur underground where they can be hard to notice.

(9) Irrigating Hardscapes

  1. Misaligned sprinkler heads hitting driveways and sidewalks send water that was meant for your landscape into the storm drain or bar ditch.
  2. Overwatering – applying more water than your soil can hold will cause the excess to run off – and if it runs off onto a driveway or sidewalk, it ends up in the storm drain or bar ditch.

(8) Broken/Leaking Sprinkler Heads

  1. Broken heads lose more than 5-10 gallons per minute (gpm) at a minimum.
  2. If your system only runs late at night when you aren’t watching it, you may have broken heads right now.  Consider running your system during the day periodically to check.
  3. Heads can break in different ways – you may have a geyser or you may have a trickle at the base.  After Winter Storm Uri many customers found their heads had split underground with very little indication above ground.

(7) Runoff

  1. Some soils take up water better than others. The “Infiltration Rate” of the soil is a measure of how quickly water can move through the soil into the root zone.  Many of the soil types in our area have infiltration rates much lower than the typical application rate of our sprinkler systems.
  2. Effectively this means that much of the water you spray on your landscape ends up running off the surface and away from your plants. 
  3. For example, if you run your sprinkler for 30 minutes and you start to see water running away from the area after 15 minutes, this is a good sign that your application rate is exceeding your infiltration rate.  You tried to put 30 minutes worth of water on your plants, but while the first 15 minutes of water was in the process of moving through the soil, the second 15 minutes stacked up and ran off to the ditch.
  4. To avoid this, the 30 minutes worth of water should be applied in two 15 minute periods with a 30-45 minute wait time between them to give the first batch of water time to move through the soil.

(6) Mixed Irrigation Zones

  1. It can be difficult to set an efficient run time on a zone with mixed heads because different sprinkler heads apply water at different rates.
  2. Different plants have different water requirements.  A zone that irrigates shrubs properly will under-water flowers, and a zone that properly irrigates flowers will over-water turf grass, etc.
  3. Mixed irrigation zones were banned in new irrigations systems installed after 2009.

(5) Missing, Misplaced, or Broken Rain Sensors

  1. Required on all systems installed after 2009; recommended to retrofit existing systems if not present.
  2. Must be installed in proper location:
  3. Needs clear view of sky to catch rain;
  4. Must be outside;
  5. Must not be hit by irrigation spray;
  6. Must be maintained:
    1. Wireless units need periodic battery changes;
    2. Internal components degrade in 2-3 years, must replace unit;
    3. Must be kept clear of brush and other obstructions;
  7. If not working:
    1. Check that it is not bypassed (switch or setting on controller);
    2. Check for damage to sensor or sensor wire;
    3. Replace battery if wireless;
    4. Replace unit asap if non-operable;

(4) Lack of Pressure Regulation

  1. High pressure causes sprayed water to atomize and become mist, which blows away from landscape.
  2. Can lose 30-50% of applied water in high winds,
  3. High pressure can increase water usage by 20%.
  4. Irrigation systems should be designed with a pressure regulator appropriate for the available water system pressure.

(3) Lack of Regular Maintenance

  1. Various problems can be avoided by visual inspections and regular maintenance:
    1. Sunken heads;
    2. Cracked and broken nozzles or heads;
    3. Holes in drip hose or leaking drip fittings;
    4. Clogged nozzles;
    5. Controller backup battery;
    6. Heads or nozzles misaligned;
  2. Solenoid valves must operate properly for your system to work and can cause significant water loss if they fail.

(2) Improper Controller Programming

  1. Run times should be changed throughout the year according to the needs of your landscape and the amount of natural precipitation received.
  2. When setting run times, consider the following:
  3. How much water does your plant need at this point in the growing season?
    1. Consult the TexasET Network (texasET.tamu.edu) or an irrigation app such as WaterMyYard (WaterMyYard.org) for irrigation needs based on current weather conditions.
  4. How much water do my sprinkler heads apply?
    1. Perform a ‘catch can’ test in your yard.
    2. Consult your system’s manufacturer for published application rates.
  5. What is the infiltration rate of my soil?
    1. How much water can physically enter my soil in a given time period?
    2. Are there other factors that might affect infiltration?
      1. Steep slopes
      2. Mulch or leaf cover
  6. Can I apply the amount of water I need in one period without creating runoff?
    1. If no, then the water should be applied in multiple periods with a rest period in between.
  7. The date and time should be set and checked periodically (don’t forget to replace the backup battery)
  8. Keep up with local watering restrictions and ensure your irrigation program fits into the allotted time windows.

(1) Poor Irrigation System Design

  1. Poor design is the most expensive problem to fix;
  2. Improperly matched plant types and sprinkler head types;
  3. Mixed zones;
  4. Heads installed too close to pavement (vulnerable to traffic);
  5. Poor coverage (heads too far apart);
  6. Redundant coverage (heads too close or zones overlapping);
  7. Problems caused by poor design lead to inefficient irrigation, and all the inefficient systems aggregated together can lead to water supply issues for the public water system.