COMMON IRRIGATION ISSUES & RECOMMENDATIONS
Common Irrigation Issues
A. Low Pressure - All sprinkler systems are designed to run at specific pressures. Improper
pressures cause poor uniformity of water distribution leading to inefficiency, wasted water and
higher costs. Low pressure puts heavy applications of water in limited areas. Some possible
reasons are: 1) poor design, 2) poor installation, 3) broken heads/pipes, 4) clogged equipment,
and 5) poor pump performance. In some situations low pressure can be corrected with a
booster pump, though this is not a stand-alone cure for most. Low pressure can be also be
addressed through re-design of the irrigation system and proper repair and maintenance.
B. Broken Sprinkler Heads – Broken sprinkler heads will prevent efficient irrigation. Replace
broken heads as soon as possible.
C. Bad seals – Sprinkler heads with bad wiper seals leak from around the seal. Replace head or
seal/cap as soon as possible.
Figure Error! No text of specified style in document.-1 Bad seal
D. Sunken Heads/Tall Grass – Sunken heads result in short throws and saturated areas near the
head because the grass near the head intercepts the sprinkler stream. Even a properly set head
will have problems if the grass near the head grows taller than the head’s pop up height. Install
heads with pop up heights that allow them to throw over the turf/shrub material at the
turf/shrub material’s tallest allowable maintained or natural height.
Figure Error! No text of specified style in document.-2 Sunken head with blockage
E. Mis-aligned heads – Sprinkler arc and radius adjustments should be made to water only the
area they were designed to cover.
F. High Pressure – High-pressure results in very fine spray which drifts downwind and creates high
evaporative losses. Pressure regulation can be easily achieved with pressure regulators at the
water source, at the remote control valve and/or at each individual head.
G. Variable Sprinkler Spacing – If the head-to-head and line-to-line spacing in a sprinkler system
vary throughout a site, the distribution of water will be uneven, leading to watering inefficiency.
In some cases, adjustments can be made in nozzles and pressures to try to account for the weak
areas.
H. Poor uniformity – This is often overcome by using much more water than would really be
necessary, so that adequate amounts are deposited everywhere. The problem with this is
excessive water use/high costs for water and the chance of damaging the plants in some areas
due to excessive water in the root zone. Possible remedies include pressure regulation and
adjustment, changing nozzle sizes, irrigating only during low wind conditions, closer sprinkler
spacing and a better designed irrigation system from the POC to the head.
Figure Error! No text of specified style in document.-3 Effects of Poor Uniformity
text of specified style in document.-4 Bubbler on established tree
Figure Error! No
I.
Bubblers – Where tree bubblers are installed for establishment of the plant and the tree
receives water from sprinklers also, turn bubbler zones off after tree establishment. If bubblers
were not zoned separately, cap bubblers after tree establishment (approx. 1 year).
Recommendations - Control System
A. Controller
1. Projects with a single controller – Replace existing ‘dumb controller’ with a smart Et
controller – program and manage based on environmental conditions
2. Projects with multiple controllers – Replace the existing ‘dumb controllers’ with a centrally
control system, including a weather station and strategically placed rain cans for
environmental based scheduling capabilities.
B. Sensors – Rain shut off devices are required by state law to be installed on all new irrigation
controllers for projects installed since January 1st, 2011. There are two types of acceptable rain
shut off devices, a rain sensor or a soil moisture sensor.
1. Rain Sensor
a. If an existing controller does not have a rain sensor, you can install one per the
manufacturer’s recommendation.
b. If a controller has a rain sensor make sure it is installed properly, operational, and set, at
minimum, to stop irrigation after .25 inches of rainfall. Setting it to stop irrigation with
even less rainfall is preferred but requires closer monitoring of the system and your
landscape.
2. Soil Moisture Sensor (SMS)
a. If an existing controller does not have a rain shut off device, you can install a soil
moisture sensor. Install per the manufacturer’s recommendations and in the driest part
of the controller’s area.
C. Scheduling – If your controller has pre-set run times for all spray zones, another time for rotors,
etc., you are probably overwatering. In general, each zone will (potentially) have a different run
time and frequency of run days based on the type of head used and the zone’s specific needs.
Recommendations - Delivery System
A. Remote Control Valves
1. If your remote control valves do not have a flow control handle, and tend to stay on longer
than 10 seconds after you have shut the valve off from the controller, replace with valves
which do have flow control. Adjust flow control handles on each valve to ensure the valve
shuts off within 5-10 seconds of being deactivated by the controller.
B. Irrigation Heads
1. Spray heads – ensure you have 6” pop-ups in turf areas, 12” in ground cover areas, and
heads on risers in shrub beds.
2. Rotor heads - ensure you have 6” pop-ups in turf areas, 12” in ground cover areas. DO NOT
use rotors on risers to irrigate large shrub areas.
3. Head type – ensure all spray or rotor heads within each zone are of the same make, model,
and features. DO NOT mix heads or nozzles from different manufacturers on the same zone.
4. Pressure Regulation – ensure all spray and rotary nozzles are installed on spray head bodies
with factory installed pressure regulating stems. Choose the correct factory preset pressure
to ensure the appropriate pressure at the nozzle/rotary (30, 40, and 50 psi stems are
available).
5. Check Valves – ensure all spray or rotor bodies come with a factory installed check valve,
regardless of elevation changes.
6. Nozzle selection – ensure you choose nozzles that deliver a ‘matched precipitation rate’
within each zone. Use the same make/model of nozzle on every head within a zone and
select the proper nozzle pattern for the area being covered.