Sprinkler Freeze Damage: What to Check After a Hard Freeze

Hard freezes in North Texas do not happen every winter, but when they do, sprinkler systems often take damage that does not show until later. A cracked backflow preventer or split fitting may hold together while frozen, then start leaking as soon as the system is pressurized again. This article explains what to check after a freeze and how to bring the system back safely.

Why Damage Shows Up Late

When water freezes inside a pipe or fitting, it expands. That can split the pipe, crack a brass body or push out a seal. While everything stays frozen, the ice may plug the crack. Once it thaws and the system is turned back on, water pours out. Many homeowners discover freeze damage weeks later, on the first warm spring day when they run the sprinklers.

Parts Most Likely to Be Damaged

Backflow preventer

The backflow preventer is above ground and holds water, so it is the most common freeze casualty. Look for cracks in the body, bulges, split bonnets, and spraying from test cocks or seams. Our article on a leaking backflow preventer covers what to look for.

Exposed pipe

The pipe that rises out of the ground to and from the backflow preventer is exposed to air. It can split, especially at fittings.

Valves

Valves in boxes near the surface, especially in boxes without lids or with cracked lids, can crack. Above-ground anti-siphon valves on some older systems are also at risk.

Heads and shallow pipe

Heads with water trapped in them and pipe with thin soil cover can crack, especially where soil is thin over rock or where pipe runs near walks and drives.

Drip parts

Above-ground filters and pressure regulators on drip zones can crack.

What to Do Before Turning the System On

1. Wait until temperatures are safely above freezing and the forecast stays that way for several days.
2. Look at the backflow preventer closely for visible damage.
3. Close the test cocks if you opened them to drain.
4. Open the irrigation isolation valve slowly, a little at a time.
5. Open the backflow shutoff valves slowly.
6. Watch the backflow preventer for a minute or two for drips or sprays.
7. Check the water meter with everything off to see if water is flowing somewhere. Our water meter leak test explains how.

If you see leaks at the backflow preventer, shut the water off again and arrange a repair.

Testing Each Zone

Once the supply side holds pressure, run each zone for a few minutes:

• Watch for geysers, bubbling or fountains in the lawn.
• Look for heads that do not pop up or spray unevenly.
• Check valve boxes for water.
• Walk the yard afterward for new wet spots.

Our zone-by-zone system check lists what to look for.

Common Freeze Repairs

• Backflow preventer repair or replacement. In Fort Worth, replacements require a plumbing backflow permit, and any repair or replacement must be tested by a registered Backflow Prevention Assembly Tester.
• Pipe and fitting repairs near the backflow preventer and on shallow lines. See our guide to broken sprinkler pipe repair.
• Valve replacement for cracked valve bodies.
• Head replacement for cracked heads.

After a Widespread Freeze

When a hard freeze affects the whole region, many homes need repairs at the same time, and plumbers and irrigation companies get busy. The February 2021 winter storm was an example. If your system is damaged after a big freeze, keep the irrigation water shut off until it is repaired, water by hand if the lawn and plants need it, and schedule the repair. Fort Worth’s rules allow hand watering at any time.

Preventing Damage Next Time

• Protect the backflow preventer before every hard freeze. Our guide on protecting your backflow preventer from freezing explains how.
• Insulate exposed pipe.
• Keep valve box lids in place.
• Make sure the freeze sensor works, so the system does not run in freezing weather.
• Consider winter shutdown. See our guide to winterizing a sprinkler system.

Ice on Walks and Streets

Running sprinklers during freezing weather can coat sidewalks, driveways and streets with ice. Besides the safety risk, Fort Worth’s irrigation code requires freeze shut-off technology on new systems. If your system ran during a freeze, check the freeze sensor and the controller’s sensor setting.

Pipe Under Thin Soil

In parts of Fort Worth and nearby cities where soil is thin over limestone, sprinkler pipe is sometimes buried only a few inches deep. That pipe is more exposed to cold than pipe buried in deeper clay. After a long freeze, pay extra attention to zones in those areas, and to pipe that runs along the edges of driveways and walks, where concrete can pull cold down into the soil.

Checking the Lawn and Plants

Freezes affect more than the sprinkler system. Warm-season lawns go dormant and brown after a hard freeze, which is normal. Some shrubs and perennials may show brown leaves or dieback. Wait until spring growth starts before judging what survived and before pruning, since damage is not always clear right away. Do not try to revive a dormant lawn with heavy watering in winter; it will green up on its own as temperatures warm. If the winter is dry, a light watering every few weeks is usually plenty.

When to Call a Technician

If the backflow preventer is cracked, you find leaks you cannot locate, or several parts were damaged, our sprinkler repair team can repair the system and help arrange backflow testing.