In Texas, do y'all drain the water out of your underground sprinkler systems for the few freezes we get each year?

It's getting down to lows of 18-20 degrees for three days starting on Monday. I saw that it got down to 30 last night where I live, and I realized I hadn't done anything for my sprinklers yet.

Don't you need to drain the lowest head on each zone? I turn on each zone and then use some sprinkler pliers to hold the lowest head on each zone open until it drains out.

Hmm, mine doesn't have anything above ground. What does that backflow preventer look like?

Is it necessary to hold the head open with a special tool, or is manually running all zones enough?

a lot of them look like this. But yours might be in the ground in the box.

I don't have anything like that either. Maybe wasn't required here at the time. My house was built in 2010 in College Station.

Thanks, if that is in a box underground, does it need to be insulated after draining the lines?

backflow preventors were for sure required in 2010. It might be a different kind and in the ground in the "box" with the shut off valve.

Or the sprinkler contractor didn't build to code


might look like this, or like this

probably not. You might consider stuffing some old towels around it in the box in the ground (after it rains though)

Ah yep. I have one of those between the house and the meter in another box.

Mine is a double check valve so a lot bigger than the one in the first picture. It is above ground and insulated but my installer said I should drain it to be safe. It is expensive, so I really don't want to have to replace it. Edit: Mine is the second picture Maroon posted.

As far as draining the lines, I just do what he told me to do. I don't know if its right or wrong, but I haven't had to replace any sprinkler heads yet.

So I have the blue one. Please treat me as stupid on what I'm supposed to do. I think I turn one valve off, turn the two small valves on top, then turn the other valve off right?

I think mine is like the first one you posted, pic below. I met with my home builder, and this is what he did:

1. Turned off sprinkler controller
2. Turned off the main supply to the system (red valve pictured)
3. Rotated each of those flat head screws a half turn to open the manifold tops.

He said if any pressure builds up from freezing in the pipes, it would push out the manifold since those tops were open. No need to drain the pipes downstream. He also said to stuff that manifold box with some kind of insulation.

Yes. That at is exactly what you do if you have the main valve in the ground.

If you don't have that main valve in the ground (my previous system didn't). Then you shut off the water intake valve (vertical pipe). Open the bleed valves. After five minutes or so then shut off the water flow to the system ( valve on horizontal pipe), and wrap the heck out of it. I'm taking about the first pic with the system that looks like it has a bell on it

I think the guy that helped me only opened the three tops that I circled below. Is that correct, or should I go back and open the fourth one too?

Also, he put the little black caps back on top. Is that correct, or should they be kept off?

Not sure. I don't have that style.

I live in North Texas, I have never done anything and I've never had a problem.

Had 7 straight days of not getting above freezing and no issues in the spring when I fired it up.

What's the purpose of those things anyway?

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What's the purpose of those things anyway?

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They are called "backflow preventers" and they stop potentially contaminated water in your sprinkler system from going back into the water supply.
Water can be forced from irrigation systems back into water supply by back pressure (forced out like by gravity) or by back siphonage (sucked out, such as when the fire department hooks up to a hydrant & starts pumping lots of water)

The type of backflow preventer you have is dictated by the degree of hazard your residence has (for example a septic system nearby causes your backflow preventer requirement to be high hazard) and by municipal code.

If your backflow preventor is in-ground (double check) it doesn't need to be drained. Had zero issues with mine last year or 2021, nor did I have any issues with the several thousand systems we've installed over the past 20+ years.

More specifically, what's the purpose of those 4 little valves on top?

Those are test cocks for the back flow tester to test the backflow. Homeowner doesn't need to touch them.

Where are you located? I've been an irrigator (commercial & residential) for 20+yrs and we've never turned off a double check (back flow valve) prior to a winter event, even snowmagedon. You have a double check. Now if you have a pvb or avb (which is above ground) you should turn off the supply.
It looks like you have a new system so you should have a new rain & freeze sensor so you really shouldn't need to turn off the controller but if that makes you feel better you can.

We oversee over 100 properties and I don't think we had one broken pipe after snowmagedon. Now we did have a broken 12" pop up that was installed on top of a shrub riser since the water frozen inside the head which was above ground

San Antonio area.

I didn't power off the controller completely. Just set the mode to off as pictured below.

I do have a rain/freeze sensor. Does it need to be set to the sensor mode for that to work? Does that mode only stop the sprinklers from running when there's rain or freezing temps?

yeah if you're in San Antonio you don't need to turn off the ball valve or the double check. Also your system should have a master valve which supplies water the the entire main line and valves. When the system or schedule stops/turns off it will close the master valve which kills all the water to the mainline (not pressurized).

If you have the controller turned to off then you really don't need to worry about rain/freeze sensor. If you leave the controller on run/auto then you need to verify that the rain/freeze sensor is active. On that controller turn the knob to sensor and see if it says the sensor is active or bypass.

national weather service is showing that you will get to above freezing each day. Sun high 44, Mon 38, Tues 39, Wed 50

also need to remove several inches of dirt from around the double check and we are required to have at least 6" of pea gravel under the double check

I didn't do anything during snowmaggedon except throw a couple of towels on top of my backflow preventer and put the lid back on. Even at 8-10 inches, that is plenty deep to not freeze.

ftworthag02 said:

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also need to remove several inches of dirt from around the double check and we are required to have at least 6" of pea gravel under the double check

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What's the reason for that? Gravel for drainage?

I'd think the dirt around it would provide insulation.

Shut off water supply to above ground backflow preventer, then drain preventer valves and leave them halfway open so freezing water can push through. Underground stuff will be fine.

They make auto drain valves that are designed to open when sprinkler lines aren't under pressure. We have cold & dry winters and they work great. Also allows us to water periodically during the winter when it's above freezing.

Example

MAROON said:

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a lot of them look like this. But yours might be in the ground in the box.

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We have this style at both our houses. Drain it well or the metal will crack.

I have an underground backflow preventer with a rainbird controller.

I'm not finding an isolation valve to turn off the water to the irrigation system alone. Are you saying i don't need to do that as long as my controller is turned to off?

The water meter in ground is only a few feet from the in ground backflow preventer for the irrigation. Would the isolation valve potentially be in there?

Correct. If you have an underground backflow like a double check then you don't have to turn off the water to it. You can just turn off the controller. If you have an operational rain & freeze sensor you don't need to turn off your controller or just make sure you don't the water days set for tonight, tomorrow, Monday, or Tuesday.