We’re fortunate to have milder winters here in Texas. However, we still experience freezing temperatures that can damage an irrigation system. Freeze-proofing your system will protect it, and at the same time allow you to irrigate during the colder months.
Above-Ground Backflow Prevention Assemblies
Although above-ground backflow prevention assemblies (BPAs) can be turned off and drained, it would mean setting up the valves to the proper position every time a hard freeze was predicted. Instead, wrapping and insulating the BPA will prevent such damage as broken valves, cracks, and warping, and still keep it always operational for irrigation.
To insulate, choose materials such as self-stick foam insulation tape, foam pipe wrap secured with heavy rubber tape, or fiberglass pipe insulation wrap. Be careful not to block the drain outlets and air vents. If using fiberglass insulation, wrap it with a waterproof tape to keep it dry — it won’t insulate when wet.
For further protection, enclose the BPA with an insulating pouch. Make sure it’s waterproof to protect the insulation. The pouch has an opening at the bottom to allow for drainage and air flow. If necessary, you can secure the pouch to the ground with small stakes to prevent the wind from blowing it away.
There are also insulated enclosures that resemble rocks you can place over the pouch for further freeze protection. These blend into your landscape and can be used all year to camouflage and protect your BPA.
Sometimes a freeze is forecast before you’ve had time to winterize. In this case, protect the BPA temporarily with items you have on hand.
Sleeping bags, sweatshirts, fleece blankets, and towels can be used for wrapping, while duct tape will keep them in place. Add a heavy-duty garbage bag to keep everything dry and place a small trash can on top for that extra protection.
In Texas we don’t have to drain our underground pipes or blow them out with compressed air to winterize them. The soil insulates the pipes, providing they’re buried below the area’s frost line of around 8-12 inches. Deeper is better, which also protects the pipes from damage due to lawn equipment, shovels, and other sharp tools.
Above-ground pipes do have to be insulated. Self-sticking foam insulating tape or foam insulating tubes work well.
The irrigation valves are usually buried below ground, or in an underground valve box, which protects them from freezing temperatures. Inspect your valve boxes, and repair or replace any broken and missing box lids you find.
Isolation valves shut off the water to the irrigation system from the main water supply and need to be freeze-proof. They can be found inside a heated room, buried in a valve box below the frost line near the meter, or located outside above ground. If outdoors above ground, protect the valve by wrapping it with foam insulation tape and a heavy plastic bag.
The “seasonal adjust” feature on your controller will allow you to manually change the winter run times to a percentage of the summer schedule.
With weather-based WIFI controllers the seasonal adjustment is automatic. These controllers make watering adjustments using different methods based on their technology and complexity. They receive their data from such sources as: historic weather information, on-site real-time sensor measurements, and daily local weather forecasts.
Program the controller for regular irrigation if you’ve overseeded to have a green lawn during the winter. For dormant lawns, change your programming to water only once or twice a month. The moisture keeps the roots healthy for re-emergence in the spring and helps insulate them from the cold.
Running your irrigation system even periodically over the winter also maintains its health by:
- Moving stagnant water and algae out of pipes.
- Blowing roots, dirt, insects, and insect eggs out of the system.
- Lubricating sprinkler seals and valve diaphragms.
Make sure your rain sensor is functioning properly to prevent winter overwatering. You’re required by the Texas Commission on Environmental Quality (TCEQ) to have rain or moisture shut-off devices for all new automated irrigation systems, or for systems with repairs involving replacement of controllers (30 TAC 344.62 (j)).
It’s a good idea to add a freeze sensor to your system if you don’t already have one. It will suspend irrigation when a set temperature is reached (e.g., 37°F), and is often combined with a rain sensor. Some Texas cities have local ordinances requiring both rain/freeze sensors.
When a Hard Freeze is Forecast
A hard freeze, according to Dr. John Nielsen-Gammon of Texas A&M, occurs when the temperature falls to 28°F or lower, and stays below 32°F long enough to freeze vegetation and cause ice formation in standing water. You need to take these extra precautions to protect your irrigation system before a hard freeze arrives:
- Turn off the water to the irrigation system at the isolation valve.
- Shut down the controller. Use the “rain”, “delay watering”, or “off” setting on automatic controllers. The programming remains intact. For some controllers you need to “suspend” the zones for a selected time period.
- Inspect the sprinklers that have check valves to make sure all the water has drained out. If the water inside freezes, it will rupture the sprinkler. Remove the sprinklers, give them a shake, and replace.
- Drip lines should be flushed out by opening the flush clips or loosening end caps and allowing the water to flow out. Reattach the clips or tighten the end caps when the water is completely drained.
- In drip systems, you also need to drain water from the filter. Loosen the filter cap (usually near the valve and drip regulator) to empty any water. Then open the filter and clean the screen or discs. Reinstall and tighten the filter cap.
In Austin, residents are eligible for a rebate when they install a rain or soil moisture sensor for the first time.
Call the licensed irrigators at Smart Earth Sprinklers at 512-694-1147 or contact us online for your sprinkler system inspection, repair, and maintenance needs.