Frequency of Residential Irrigation Maintenance Problems1
An improperly functioning residential in-ground irrigation system may result in some areas of the landscape showing stress while other areas are well watered. Alternatively, the poorly functioning irrigation system may be applying excess water, resulting in damage to landscape plants and loss of nutrients from the soil. The causes of the poorly functioning irrigation system may be from an inefficient design, improper installation and/or inadequate system maintenance over time.
A poorly designed irrigation system or one installed improperly may not have head-to-head sprinkler spacing, matched application rates of rotor sprinkler nozzles, or spray heads in the same zone. It could also have plants with different water requirements located in the same irrigation zone (Smith 1997). Improper maintenance issues may include clogged or leaking sprinklers, sprinklers obstructed by plant material, and misadjusted sprinklers that over-spray onto sidewalks or streets.
Irrigation system audits or inspections provide a method of determining the condition of the components and the application uniformity of coverage. In Florida, a fleet of Mobile Irrigation Labs (MILs) provide auditing services to analyze irrigation systems and educate property owners on how to improve water use and promote conservation. The MILs give recommendations on the improvement of existing irrigation systems and equipment, and educate their customers and the general public on water conservation, irrigation planning, and irrigation management. Originally developed for agricultural purposes, now Urban Mobile Irrigation Labs (UMILs) perform the same service for residential clients. The service areas covered by an MIL or UMIL in Florida can be located from the Florida Department of Agriculture and Consumer Services' website at: https://www.fdacs.gov/Agriculture-Industry/Water/Mobile-Irrigation-Labs.
An UMIL has three levels of evaluation (Palm Beach Soil & Water Conservation District 2008):
pressure and flow check
catch can test (optional)
First, visual inspections are conducted to determine if the system is in disrepair (leaks, broken sprinkler heads, etc.) or has poor coverage. If the system is found to be in poor condition, the other levels of evaluation are not carried out until the repairs are made. Pressure and flow checks on individual sprinkler heads or emitters are carried out next. Catch can tests can be used to measure irrigation uniformity and the application rate (how fast the sprinklers apply water) of an irrigation zone. In the urban setting, the catch can test for distribution uniformity is rarely done by the auditors because it is very time consuming. In a typical residential irrigation system with 4 zones, it would take a significant amount of time to complete the steps for the test (laying out the small cans in each zone, running the irrigation for the set amount of time, and then recording all the volumes). Experienced auditors can visually assess poor distribution caused by maintenance issues or inadequate irrigation design. Another way the auditors calculate the application rate of an irrigation zone is to run the zone for a set time and record the volume observed from the water meter converted to depth over the zone's irrigated area.
Under the visual inspection, the technician has a list of 34 codes to describe the problems seen in the irrigation system as shown in Table 1 (the same codes are used for agricultural audits). Any one residence may have multiple problem codes.
Analyzing the frequency or number of times an irrigation maintenance problem occurs will provide a list of the most common irrigation maintenance problems in the residential irrigation system. Knowing the most common problems should increase awareness, which will lead to prevention or corrective action of these problem areas and help reduce water wasted with in-ground irrigation systems.
Urban Mobile Irrigation Lab audit information was obtained from the Florida Department of Agriculture and Consumer Services. It consisted of the problem codes per UMIL audits from about 2003 to 2007. After removal of incomplete and corrupted data, the problem codes of 3,416 audits of urban irrigation systems remained.
The frequency of occurrence of each code in all 3,416 audits was tabulated and then the codes were ranked from the most frequent occurrence to the least.
The UMIL audits were concentrated mainly in south Florida.
In the sample of 3,416 residential irrigation systems evaluated by the Florida UMILs, the quantity of problems per audit (or home) ranged from 1 to 18. There were no homes that did not have at least one problem. The first eleven most frequent problem areas represent 80% of all the problems recorded and are listed in Table 2.
Five problem areas represent half of all recorded problems. They are as follows:
Turf and landscape area irrigated in the same zone
Mixed sprinkler/emitter sizes & unmatched application rates in the same zone
Stream of water blocked by vegetation
Operating time too frequent
Operating time too long
Turf and Landscape Area Irrigated in the Same Zone
In 70% of the residential systems evaluated, the turf and landscape (ornamental beds) areas were irrigated by the same zone. This means that ornamentals and turfgrass are irrigated simultaneously because an irrigation zone covers both types of plant material (Figure 1). In most cases, ornamentals need less frequent irrigation than turfgrass. If the zone is programmed with a run-time for the water requirement of the turfgrass, the result could be over-irrigation of the ornamentals.
How this is "fixed" depends on the severity of overlap. A few nozzles hitting the ornamentals will probably not justify changing the system. However, if there are rotor sprinklers or spray heads designed for turf irrigation irrigating ornamentals beds instead, they probably should be replaced with a lower flow-rate sprinkler or removed altogether.
On newly installed irrigation systems, this overlapping of two different plant materials should be avoided. The irrigation contractor should have the landscape plans and install the irrigation system zones according to plant type. Correcting this problem has a potential to save water, depending on how many spray heads or rotor sprinklers are removed (Table 3).
Mixed Sprinkler/Emitter Sizes and Unmatched Application Rates in the Same Zone
Mixing sprinkler types with different flow rates or application rates in the same zone was found to be the next most frequently occurring problem (Figure 2). For pictures of the different sprinkler types see Operation of Residential Irrigation Controllers at https://edis.ifas.ufl.edu/ae220. The result of this problem could be either over- or under-irrigation of part of the zone. If the rotor or spray head has a higher application rate than designed, the plant may not effectively use the excess water. If the application rate of an individual rotor sprinkler or spray head is less than designed, the homeowner may see that area is drier than the rest of the zone and increase the run-time to compensate, over-irrigating the other areas of the zone.
Unmatched application rate rotor sprinklers or spray heads can easily be fixed by changing out the incorrect nozzle and installing the correct one. The size of the mismatch will determine the quantity of water saved. Changing out the nozzles should involve only a moderate investment of time and money (Table 3).
Stream of Water Blocked by Vegetation
The next most often occurring problem is the water stream from the sprinkler is deflected or blocked by vegetation (Figure 3). When the water hits vegetation close to the sprinkler, it is concentrated in certain areas and prevents spray uniformity. In older homes, either the vegetation could have grown substantially since the irrigation system installation or the system was installed without the proper risers to clear the vegetation. If the stream of water is being blocked, then the plant material on the other side is not receiving the water the system was designed to deliver. This could stress the plant material or possibly result in an ill-advised decision to increase run-times to try to compensate for the lack of water in those areas.
If vegetation is blocking a stream of water from a nozzle, the options to fix it include cutting or trimming the vegetation, installing a new sprinkler with a higher riser, moving or removing the offending sprinkler or spray head, or replacing vegetation in the area not receiving water with drought-tolerant plants. Any water savings after fixing the problem may be minimal and depend on the area being blocked and the type of vegetation not receiving the full coverage. If the water blockage is causing turf stress, then one of the repair options should be considered (Table 3).
Operating Time too Frequent and Operating Time too Long
Two issues occurring in about 50% of the homes audited dealt with the irrigation timer. Either the timer was set to run (irrigate) too frequently and/or too long (longer than necessary run-time per zone). These homes were probably not following the days of the week watering restrictions set by the water management district or the local water utility. Given the same run-times, irrigating 3, 5, or 7 days a week will result in more water usage and over-irrigation than irrigating with the same run-time 1 or 2 days a week. When the irrigation timers are set for a longer duration or run-time per zone than necessary the irrigation water will probably exceed the water-holding capacity of the soil. The excess water will either runoff or be lost to deep drainage.
These problems can easily be changed by re-programming the irrigation time clock. A properly set irrigation time clock can reduce irrigation water use by 30% (Haley et al. 2007). This change has the potential to quickly save a significant amount of water. Instructions on programming the irrigation time clock can be found in Operation of Residential Irrigation Controllers at https://edis.ifas.ufl.edu/ae220. Changing the time clock settings may be the most cost-effective change to save irrigation water (Table 3).
Smart Irrigation Controllers
To lessen the need for homeowners to worry about the settings on their irrigation controller/timer, the irrigation industry has developed "smart" irrigation controllers. The two types are as follows:
soil moisture sensor controllers
(For more information on the application of these "smart" controllers in the residential irrigation system see: Smart Irrigation Controllers: What Makes an Irrigation Controller Smart? found at https://edis.ifas.ufl.edu/ae442.)
The evapotranspiration-based controllers operate using weather data and site specific inputs such as sprinkler and plant type. The controllers calculate the water requirement of the plants during a time period and adjust or operate the irrigation system to replenish the water lost by the plant (evapotranspiration). See: Smart Irrigation Controllers: Operation of Evapotranspiration-Based Controllers found at https://edis.ifas.ufl.edu/ae446.
Soil moisture sensor controllers measure the actual soil moisture where plant roots are located. When the soil moisture goes below a certain value (measured by how dry the soil is) the irrigation system is allowed to irrigate. Conversely, if the soil moisture is above that value, then there is sufficient moisture in the soil for plant growth and the irrigation system will not be allowed to irrigate. See: Smart Irrigation Controllers: How Do Soil Moisture Sensor (SMS) Irrigation Controllers Work? found at https://edis.ifas.ufl.edu/ae437.
Both of these types of "smart" irrigation controllers can save water over conventional irrigation time clocks with no control device. Once set up properly these controllers can relieve the burden of changing the irrigation controller/timer to match the changing landscape water needs.
The majority of Florida in-ground irrigation systems have some type of maintenance problem that could be causing excessive water use. Inspections should be done on a regular basis. The Florida UMILs are qualified to do these inspections and will provide them free of charge. Homeowners not in a UMIL service area but who would like to have their irrigation system inspected should call their local water utility. They may offer a similar program or can recommend some qualified irrigation contractors.
Appreciation goes to Camilo Gaitan with the Florida Department of Agriculture and Consumer Services for supplying the UMIL data.
Dukes, M.D., and D.Z. Haman (2008). Operation of residential irrigation controllers. AE220. Gainesville: University of Florida Institute of Food and Agricultural Sciences. https://edis.ifas.ufl.edu/ae220 (April 2017)
Dukes, M.D., M. L. Shedd, and S. L. Davis (2009). Smart irrigation controllers: operation of evapotranspiration-based controllers. AE446. Gainesville: University of Florida Institute of Food and Agricultural Sciences. https://edis.ifas.ufl.edu/ae446 (April 2017)
Dukes, M.D., M. Shedd, and B. Cardenas-Lailhacar (2009). Smart irrigation controllers: how do soil moisture sensor (SMS) irrigation controllers work? Gainesville: University of Florida Institute of Food and Agricultural Sciences. AE437. Gainesville: University of Florida Institute of Food and Agricultural Sciences. https://edis.ifas.ufl.edu/ae437 (April 2017)
Dukes, M.D. (2009). Smart irrigation controllers: What makes an irrigation controller smart? AE442. Gainesville: University of Florida Institute of Food and Agricultural Sciences. https://edis.ifas.ufl.edu/ae442 (April 2017)
Haley, M.B., M.D. Dukes, S. Davis, M. Shedd, and B. Cardenas-Lailhacar (2008). Energy efficient homes: the irrigation system. FY1043. Gainesville: University of Florida Institute of Food and Agricultural Sciences.
Haley, M.B., M. D. Dukes and G.L. Miller (2007). Residential irrigation water use in Central Florida. Journal of Irrigation and Drainage Engineering, 133, 427–434.
McCready, M.S., M. D. Dukes, and K. Migliaccio (2009). Basic repairs and maintenance for home landscape irrigation systems. AE451. Gainesville: University of Florida Institute of Food and Agricultural Sciences.
Palm Beach Urban Mobile Irrigation Lab: Quarterly Report (2008). Palm Beach County Soil & Water Conservation District.
Smith, S. (1997). Landscape irrigation (1st ed.). New York, NY: John Wiley and Sons.
UMIL problem codes (Palm Beach Soil & Water Conservation District 2008).
Eleven most frequent problems in residential evaluations of 3,416 homes.
Estimated effort, cost, and water savings of the top five UMIL problem areas.