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You are here: Home > Sprinkler School™ > Sprinkler System Basics > Winterizing Your Irrigation System > Guide To Winterization
A Homeowner's Guide to Winterization

In a freezing climate it is advisable to "winterize" the sprinkler system in order to avoid damage. Special attention should be given to removing water from the pipes, valves, and sprinkler heads, before freezing occurs. This may be accomplished using three techniques; the manual drain valve method, the automatic drain valve system, or the air blow-out practice.

Caution! Please refer to the How to Winterize System Components section to fully complete the winterization process for your system.

Click the links below for additional reference:

  • Hunter Irrigation Notes: Freeze Protection (332 K)
  • Hunter: Winterizing Your Irrigation System (108 K)
  • Rain Bird: Winterization, PRS-Dial (3,018 K)


Design: The manual drain valve should be installed on the sprinkler system mainline at the lowest point of the system. Additional manual drain valves must be installed if there are multiple low points along the run of pipe where water collection might occur. A ball valve, gate valve, "Stop and Waste" valve, or a simple threaded pipe with a cap may be used to provide drainage. Piping should be sloped properly to allow water to drain out. If the valve is located outdoors, it should be installed over a "dry-well" (underground pit filled with gravel to drain water away from the piping) to allow the amount of water that is drained to percolate into the soil. If the valve is installed indoors, make sure the volume of water can be collected or drained without the risk of overflow or flooding.

Procedure: Wear proper eye protection. The manual drain valve or drain cap is pressurized at this time and could cause physical injury if opened before the pressure is first relieved. Please follow the steps below carefully .

  1. Turn off the sprinkler system mainline shut off valve. ( A )

  2. Open one of the sprinkler system control valves, either manually, or electrically from the timer, to relieve pressure on the sprinkler system mainline.

  3. Slowly open the manual drain valve. ( B )

  4. Repeat this procedure for all manual drain valves on the sprinkler system mainline.

  5. Caution! Please refer to the How to Winterize System Components section to fully complete the winterization process for your system.


Sprinkler Warehouse highly suggests you read The Freeze Drain...Irrigation's Best Kept Secret for a good understanding of why you should use automatic drain valves on any sprinkler system installed in a freeze prone area of the country.

Description: Caution! Do not install automatic drain valves on the sprinkler system mainline unless you use the Mainline 1/2" (MPT) Harmony Drains? which are guaranteed up to 2500 psi burst pressure! They are found on the following link: Harmony Drains for use on a main line pipe.

The automatic drain valves, Mainline, Lateral line, Elbow, and Siphon Harmony Drains, are devices which are installed on the sprinkler pipes or heads. It is a convenient and efficient product for removing water from the lateral pipe network running from the sprinkler system control valves to the heads. Typically, automatic drains should be installed after or downstream of the sprinkler control valves. Only the Mainline Harmony Drains are designed or engineered for use on mainlines. The drain valve will open every time the system is shut off. This will drain all the water out of the pipe providing the valve is installed at the proper location, which is the low point on the line. When the system is pressurized, the water shuts the valve off by pressing against the sealing mechanism, allowing water to flow through the pipe and on to the sprinklers in proper fashion.

Design: Install automatic drain valves at the low points in the sprinkler lines. Generally speaking, two or three drains per zone (or station) are adequate to do the job. The drain valves have either 1/2"or 3/4" male pipe threads. Use two or three wraps of teflon tape around the threads to ensure a proper seal. Simply screw the drain valve into a threaded fitting positioned downward. If you have a soil condition which drains poorly, we suggest digging a small hole directly beneath the drain and filling it with gravel to assist drainage.

Procedure: Automatic drain valves remove water from the system every time it is shut off. No manual intervention should be required. Check for excessive puddling on the soil surface should one of the drains become stuck open during sprinkler operation.

Caution! Please refer to the How to Winterize System Components section to fully complete the winterization process for your system.

How to Blow Water out of the Lines Using Compressed Air

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