This document provides instructions for winterizing irrigation systems in two main ways: manually draining the system or blowing it out with compressed air. It describes how to properly drain valves, blow out pipes from the highest to lowest points using sufficient air pressure and flow, and winterize other system components like controllers, pumps, backflows, and drip systems. The goal is to drain all water from the pipes and components to prevent damage from freezing over the winter.

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Irrigation System Winterizing
•Water expands when frozen
•Frozen water expands in pipes and can
burst
•Pipes broken with ice usually have long
(length wise) spiraling cracks
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Winterizing in two ways:
Manually draining or by blowing it out
• Blow out winterizing is the more common
on large systems.
• Ball fields/residential may use drain
valves.
1.Manually –
• To winterize a system manually there has to
be drain off valves strategically located
• Drain off valves are costly to install
• Usually ¾-2”
• Usually placed in a box over a gravel sump
• Pipe should maintain a slope of 1 % to the
low points
• Make sure to have detailed “as built” to
locate drains
• Drain valves MUST be in low spots of
system
Grounds Maintenance October 1988
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•Automatic drain valves available but they
drain down after every water cycle.
Grounds Maintenance October 1988
2.Blow out:
•Note for first one or two times to blow
out hire a contractor and take detailed
notes. Blowing a system out can be
dangerous when disconnecting BE
CAREFUL
•Blow out will do a better job than
manual or gravity drains – especially
older systems that have experienced
frost heaving of pipe leaving low areas!
•To blow out a system a compressor has
to be rented or purchased
•If renting a compressor reserve early
•If renting consider sharing with other local
clubs
•A contractor may be hired
•Contractor blow out costs are high
•If hiring a contractor warrantees are often
available
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Compressor ratings
•visualize “ball of air the diameter of the pipe”
rolling along pushing air towards an open
valve making sure no water gets over or
behind the ball
Air front Water
•Toro recommends air pressure 40psi or
damage to sprinklers may occur.
•If compressor is to small the air has a hard
time pushing the water and may actually flow
over the top of the water.
Water
Air front Water
Compressor ratings continued:
•Key to success is cfm (volume of air) not so
much pressure
•For large systems should have a minimum
compress or 600cfm.
•25 cfm or larger for small residential
•750 cfm for a mainline system with 14” pipe
(may use two
•900 cfm for a system with 16” mainline pipe
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Compressor ratings continued:
•Do not exceed 50psi or damage may result to
sprinklers
•Do not open or drain any pipe before hooking
up compressor (it may not work well to reach
pressure to push water)
•Do not open too many valves at one time.
Blowing out the system:
1.Hook up Compressor minimum (on large
system 11/2 ”)
2.Use a length of galvanized pipe between
compressor and pvc as heat can build up.
Blowing out the system continued:
3.Begin blowing out system from farthest and
highest point
4.Familiarize yourself with irrigation system
• Know- flow or laterals to
• Know where dead-ends are and work
towards those areas
5.When air is expelled begin activating valves
6.When head starts blowing air move to next
sprinkler
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Blowing out the system continued:
7.Gear driven heads turn much faster with air
then water – Don’t have them operate for
prolonged periods on air movement (more
than 1 minute)
Blowing out the system continued:
7.Greens and tees (I did last).
8.Switch with assistant and go through
everything one more time
9.1 to 2 sprinklers on each (Supt. and Assist.)
or loss of head pressure.
Controllers
• Mouse proof
• Leave power on to keep transformers (for
mechanical clocks) working, this aids in
keeping them dry.
• Solid State (in 1990) Toro recommended
they be taken in ????
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Pump / Backflow Winterization:
Improper winterization of can cost big $.
Improper winterization of pumps can lead to
broken:
•Casings
•Main control valves
•Isolation valves
•Check valves
If an unexpected freeze in forecast (more than
24 hrs. at 28° or less) (before winterization of
pump or backflow) - then consider:
•Anything to keep the pump area above
freezing
•Heat strips
•Electric heaters
•Kerosene heaters
•Electric light bulbs
•Crack a valve just a little to keep water
flowing
For new construction many pump houses are
now heated!
Winterizing
•Refer to manual
•Start by closing the inlet isolation valve
•Manually Drain down valves from drain plugs
•Drain and pull out suction lines
•Use a small compressor to blow out areas
that water may become trapped.
•Leaves drain plugs open
•Make the priming systems of pumps is
drained down
•Common mistake -leaving water in pressure
relief valves- drain in turbine pump by
removing bonnet valve and draining.
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After winterizing it may be a good
time to begin preparing for the next
season!!
• Clean and sandpaper rust
• Paint pumps or rusted areas with a good
quality rust proof paint
• Check all fittings (electrical as well)
• Grease all fittings on pump station
• Change oil if turbine pumps
Landscape winterization
• Be aware shrub risers will be susceptible to
earlier freezing
• May have manual drains
• Open and drain above ground fittings and
hose bibs
• Open petcocks and drain down back flow
devices
• Be aware that frost free hose bibs may not
function properly when vacuum breakers are
installed
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•Drip emitters
• Usually self draining
• Excessive pressures could damage
barbed fittings
• PVC fill lines should be graded with drains
in the low lying areas
• Drain all filtration devices
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