Irrigation systems and backflow preventers in a freeze
The brass backflow preventer sticking out of the ground beside the house is often the first plumbing to break in a Midlands freeze. It is full of water, above ground and fully exposed to the wind.
Last reviewed October 30, 2026 against the sources listed below. General information, not insurance or legal advice.
Pipe-freeze risk for Newberry right now
Pipe-freeze risk, the week ahead: Low
- Coldest hour: 50°F, Fri, Oct 30 at 8:00 AM ET
- Hours at or below 32°F: 0; at or below 28°F: 0; at or below 20°F: 0
No freezing temperatures in the hourly forecast. A good week to find your main shutoff, buy faucet covers and check pipe insulation before the first hard freeze.
Computed from the National Weather Service hourly forecast for Newberry, updated Fri, Oct 30 at 7:42 AM ET. Low spots, river bottoms and rural yards often run colder than the forecast point. Thresholds: 32°F freezing; 28°F the NWS hard-freeze level; 20°F the freeze-alert threshold for homes in southern states from University of Illinois research.
No active weather alerts for the area right now. Water and weather center
Why it is there
A backflow preventer keeps water from your irrigation lines, which can pick up fertilizer, soil and lawn chemicals, from being pulled back into the drinking water supply. South Carolina's drinking water regulation, R.61-58.7(F), requires at least a residential dual check on residential lawn irrigation systems, and a reduced pressure (RP) assembly or an air gap where chemicals are injected. SC DES requires public water systems to run cross-connection control programs, and assemblies tested under those programs must be tested by a state-certified tester. Your water provider can tell you what it requires for your connection.
Winterize before the first hard freeze
- Turn off the irrigation system's water at its shutoff valve, usually before the backflow device, in the crawl space or a valve box.
- Turn the controller to "off" or "rain" mode.
- Drain the system following the manufacturer's or installer's directions. The American Red Cross advises draining sprinkler supply lines this way and not putting antifreeze in them unless directed.
- Drain the backflow device as your installer recommends. Some systems need to be blown out with compressed air by a professional.
- Cover the backflow device with an insulated cover made for it, without blocking any relief port.
If you water through the winter
Some lawns need occasional winter watering. If you keep the system on, insulate the backflow device, and shut it off and drain it before any night forecast in the 20s.
If it splits
- Close the irrigation shutoff, or the main if there is no separate shutoff.
- Have it repaired or replaced by a licensed plumber or irrigation contractor. Depending on your water provider, a replaced assembly may need to be tested before use.
- Insurance may or may not cover outdoor equipment; check your policy.
Pools and outdoor kitchens
The same goes for pool supply lines, outdoor showers and outdoor sinks: drain them as the maker directs, and shut off and drain the lines feeding them from inside the house.
Frequently asked questions
Does South Carolina require a backflow preventer on lawn irrigation?
Yes. R.61-58.7(F) requires at least a residential dual check on residential lawn irrigation systems, and an RP assembly or air gap if chemicals are injected.
How do I keep my backflow preventer from freezing?
Shut off and drain the irrigation system before hard freezes, and use an insulated cover. Follow your installer's instructions.
Policies vary. Check your own policy and ask your insurer or agent about anything that affects your claim. Rules can change; this page reflects the sources below as of October 30, 2026. NewberrySCPlumbing.com is not a plumber, insurer, adjuster or law firm.
Find local help
Plumbers and well contractors serving Newberry County · Ask for help with a frozen or burst pipe · Who to call · Counties and towns