Each watering system
performs differently depending on the types of
sprinklers, water pressure, and system design.
The Calculator allows you to select the most
common types of irrigation systems and uses
average values for each system. For example,
when you select "sprinkler" on the Landscape
Watering Calculator, a default number is used
in a mathematical formula to create your
custom watering schedule.
- Spray sprinklers are used to
water lawns, planters, and slopes. The spray
nozzle is made of plastic or brass and is
attached to a pop-up or shrub sprinkler body.
There are many different makes and models
designed to cover areas up to 15 feet wide
when operated at 30 to 40 p.s.i. of water
pressure. Average spray sprinkler systems are
about 65% uniform; compare this to a gear
rotor system which can be up to 85% uniform.
The more uniform a system is, the less water
is required to cover the planter area evenly.
- Impact rotors use the force of
the water hitting a spring loaded arm to turn
the sprinker. The mist and overspray caused
by the impact arm wastes water and is a
disadvantage of this type of sprinkler. The
rotors are made of plastic or brass and cover
areas from 15 to 65 feet wide, depending on
the water pressure and size of the nozzle.
Average operating pressures range from 35 to
85 p.s.i. and impact systems can be up to 75%
- Gear rotors are a relatively new and
improved type of sprinkler. They use water
pressure to turn gears inside the sprinkler
body, which in turn makes the nozzles rotate.
Unlike impact rotors, there is almost no
wasted water from splashing and overspray.
Other advantages of gear rotors include a
large selection of nozzles, precision
adjustments, low cost, and improved uniformity
which reduces overall water use. The rotors
are made of plastic and cover areas from 15 to
65 feet wide, depending on the water pressure
and nozzle size. Average operating pressures
range from 35 to 85 p.s.i. and gear rotor
systems can be up to 85% uniform.
- Micro-spray sprinklers are just like
regular spray sprinklers only smaller. They
are made of plastic or brass and attach to
pop-up bodies or to flexible polyethylene
tubing. One advantage of a micro-spray system
is that water is able to soak into the soil
more slowly, preserving the air/water balance
in the root zone and reducing runoff. These
systems are ideal for very small planter areas
because the spray pattern can be precisely
adjusted. Distance of coverage is from 1 to
15 feet. Proper filtration and pressure
regulation is required. The operating
pressure range is 15 to 30 p.s.i.
- Bubblers are used to irrigate
individual plants, and are often placed inside
watering basins and tree wells. Installed on
rigid plastic pipes 4 to 6 inches above the
soil surface, they are ideal for sandy soils
where drip irrigation is less effective.
Pressure regulated bubblers deliver a uniform
amount of water to each plant, and they
require very little maintenance. The
operating pressure ranges from 30 to 50 p.s.i..
- Drip systems can be the most
efficient way to irrigate your landscape,
using the least amount of water. There is
very little evaporation and no over-spray when
the water is placed directly on the soil. The
slow application of water also helps to
maintain the air/water balance in the root
zone, which promotes optimum growing
conditions. Most drip systems operate at 15
to 30 p.s.i. and can have a uniformity rating
of 90 to 95%. Proper filtration, pressure
regulation, and maintenance are essential to
good system performance.