Irrigation System Maintenance Introduction

Landscape irrigation uses 50 percent or more of the water provided by many utilities.  A poorly maintained irrigation system means that much of this water never reaches its intended source and is lost to runoff, evaporation and deep watering below the root zone.

Maintaining irrigation systems is one most effective ways to reduce wasted water, reduce pollution from run-off and over-irrigation, and improve plant health by applying the correct amount of water where it can be utilized by the landscape.

Irrigation system geyser from a broken headAt a minimum, a check of the irrigation system should be performed twice seasonally. Once at the beginning of the season when the system is first turned on and again halfway through the season.  Ideally, the system should be checked on a monthly basis.

The basics of irrigation maintenance are:

1.  Inspect the controller and make sure it’s plugged in and functioning:

2.  Update the time and date

3.  Check the connection on all of the wires – make sure that rain, wind, or soil moisture sensors are connected

4.  Replace the back-up battery

5.  Change the schedule to reflect the current season and irrigation needs of the landscape

6.  Turn on each zone and look for system damage

 

Examples of System Damage and Problems

Leaking valves or pipes

Leaks can occur as a result of weather damage (freezing and thawing), damage from shovels and other sharp tools, vandalism, tree roots, and normal aging of the system.  Leaks from valves and pipes may be large and very obvious.  Smaller leaks may not show up immediately and will require some detective work.  Replace or repair damaged valves and pipes. 

Flood from leaking rotorBroken or missing heads

Damage can occur to sprinkler heads from lawn mowers, vandalism, improperly installed heads, and normal wear and tear.  Replace damaged or missing heads immediately.  Installing heads on swing pipe allows the head to “float” in the soil and reduces the damage that can result from lawn mowers and other heavy objects.

Clogged nozzles

Clogged nozzles occur as a result of debris entering the irrigation system, a dirty water source, and normal wear and tear.  Flush system at the beginning of the irrigation system, install screens on sprinkler heads, replace clogged nozzles, and improve system filtration.

Seal leaks

Over time, dirt and debris can wear out the wiper seal resulting in leaks around the top of the spray head.  If the spray head consists of a single unit the entire head must be replaced; with some spray heads it is possible to screw off the top of the sprinkler head and replace.

Sidewalk geyserSunken heads

It is not uncommon for sprinkler heads to settle over time. Even when the soil is packed around them during, the weight of lawn mowers and other heavy equipment on wet turf can cause the heads to settle. Grass clipping, soil, and other debris can build up around heads resulting in a head that doesn’t clear the grass adequately and disrupts the spray pattern. Current best management practices call for higher mowing heights – older systems may have been designed for shorter turf.  Heads can be raised by using taller sprinkler bodies, or installing risers.  Cutting turf away from heads is another solution but must be seasonally.

Tilted heads

Lawn mowers and wet soil can cause newly installed sprinkler heads to tilt resulting in uneven coverage.  If possible install the sprinkler head on swing pipe and move the head out of the line of mowers and other equipment that may cause the head to settle or shift.  Otherwise reposition the head and pack the soil around it carefully.

Table 1 shows an estimate of the number of gallons wasted annually from damage that can occur to the system.  Water wasted (gallons) is calculated on a 26-week irrigation season, 3.5 events weekly (91 irrigation events) and 20 minutes per event.

Table 1: Water waste from typical irrigation system damage 

Problem

Flow Rate (gpm)

Run time/event (minutes)

Irrigation events/ week

Events/ Year

Waste/year (gal)

Lateral line leaks

5

20

3.5

91

9,100

Seal leak

4

20

3.5

91

7,280

Break in drip line

3

20

3.5

91

5,460

Missing or broken head

6

20

3.5

91

10,920

 

Problems affecting the efficiency of the system

Misaligned heads

Misaligned heads result in overwatering parts of the landscape and brown spots in other areas of the landscape.  Realign heads according to manufacturer’s instructions.

Misting and oversprayOverspray (runoff)

Overspray can result in poor distribution uniformity, overwatering, and runoff on hardscapes.  Reduce or eliminate overspray by adjusting system pressure, adjusting nozzles, or installing the proper size and type of nozzle.

Pressure Problems

High pressure causes problems such as misting from spray heads and rapid rotation of impact rotors resulting in poor coverage and potential damage to the irrigation system. Installation or adjustment of a pressure regulator or installation of pressure regulating heads can eliminate the problem.

Failure of heads to pop-up or rotate is often a symptom of low water pressure.  Low pressure can also result in poor coverage and dry spots in the landscape.  Adding a booster pump, watering during off-peak times, or reducing the number of heads on a zone can increase pressure.

Incorrect Spray Arc

Observe the spray pattern of the sprinkler heads on each zone and adjust the pattern if possible.  If necessary, replace the nozzle with one that has the correct spray pattern.  Older systems in particular may need to be updated with different nozzles as manufacturers are making nozzles to fit strips and narrow areas.

Table 2 shows an estimate of the number of gallons wasted annually from system inefficiencies.  Water wasted (gallons) is calculated on a 4,500 gallon (17.03 m3) event over a 26-week irrigation season and 3.5 events weekly (91 irrigation events).

Table 2: Water waste from typical irrigation inefficiencies

Problem

Estimate of event volume affected

Volume of total event

(gal)

Events/ week

Events/ Year

Waste/year (gal)

Misting (high pressure)

10%

4,500

3.5

91

40,950

Misaligned heads

5%

4,500

3.5

91

20,475

Overspray

15%

4,500

3.5

91

61,425

Mismatched heads

4%

4,500

3.5

91

16,380

Although some of the repairs may require the help of a landscape professional many of them are relatively simple and can be easily mastered by the homeowner. Irrigation maintenance is one of the most important factors in reducing water waste in the landscape.  In addition, a well-maintained and properly adjusted system is essential for a healthy, beautiful, landscape.