Every January a few customers around Monticello call because water is spraying out of a cracked pipe next to the house after a hard freeze. Irrigation here does not need the full compressed-air blow-out they do up north, but it does need a few things done before the first hard freeze, because the parts that are above ground will break when the water inside them turns to ice.
What freezes and what does not
The buried pipe in a Big Bend irrigation system is safe. Our ground does not freeze more than an inch or so, and lines six to twelve inches down never see it. Sprinkler heads pop down and drain. The vulnerable parts are the ones exposed to air:
- The backflow preventer. The brass assembly standing above ground near the meter or the well, with test cocks and valves. It holds water, it is metal, and it cracks in a hard freeze. It is the most common freeze casualty and the most expensive small part on the system.
- The pump and its plumbing on a well system: the pressure tank, the pump housing and the pipe between them if they are outside or in an unheated well house.
- Above-ground pipe anywhere: the riser from the meter, exposed runs along a foundation, hose bibs that feed drip lines.
- Drip and micro-irrigation lying on the surface in beds.
- The controller, if it is a cheap one in an unheated shed. Electronics usually survive; the battery backup often does not.
Before the first freeze
The first freeze in Jefferson County usually comes in November, sometimes late October, so do this by the end of October:
- Turn the irrigation off at the controller and leave it off through winter. Dormant warm-season turf does not need water. Watering during a freeze also coats the lawn and everything nearby in ice, which does real damage. Our dormancy post covers why the grass is fine without it.
- Shut the isolation valve upstream of the backflow preventer, then open the test cocks and the downstream valve to let the water drain out of the assembly. It cannot crack if it is empty.
- Insulate what cannot be drained. A foam backflow cover or an insulated bag over the assembly, foam pipe wrap on exposed pipe, and a heat source in a well house if the pump plumbing is exposed. A cardboard box and a towel are not enough for a night in the teens.
- Drain surface drip lines or disconnect them at the source and let them empty.
- Pull the battery from a controller in an unheated space if the manual says it can be stored, or just note that it may need replacing in spring.
The night of a hard freeze
If you did the list, there is nothing to do. If you did not, and a night in the low 20s is forecast, at minimum shut the isolation valve and drain the backflow, and wrap it. Do not leave water running through the system to "keep it from freezing"; that is a myth that ends with an iced lawn and a cracked assembly anyway. Our guide to frost and freeze protection covers what to do for the plants.
After the freeze
Once temperatures are back above freezing for good, in late February or March, turn things back on slowly:
- Close all the drain points and test cocks on the backflow.
- Open the isolation valve slowly. Fast pressurization is what breaks fittings that survived the cold.
- Walk the system with each zone running. Look for water where it should not be, heads that do not pop, and pressure lower than last fall.
- Check the backflow for weeping at the seams; a cracked body sometimes only shows under pressure.
Do not start the regular watering schedule until the lawn is green and growing. A dormant lawn in March needs almost nothing. The dry spring watering post covers when to ramp up.
Well pumps specifically
A pump in a well house needs the house to stay above freezing, which means a heat lamp or small heater on a thermostat, or thorough insulation. A pump exposed on a pad needs the plumbing drained or wrapped and, in a serious freeze, a cover with a heat source inside. Check the pressure switch and the tank drain for drips after any freeze; the small fittings crack first.
FAQ
Do I need to blow the lines out with compressed air?
Not here. The buried pipe does not freeze. Drain and protect the above-ground parts only.
Can I leave the system on and just skip watering days?
Turning it off at the controller is safer. A rain sensor or a schedule glitch can start a cycle during a freeze.
What does a cracked backflow look like?
Usually a hairline split in the brass body that weeps or sprays under pressure. It has to be replaced, and it is often a licensed plumber's job.
Do you check systems in spring?
When we set up a maintenance plan we walk the irrigation and flag anything broken before the dry season.
If you want the system shut down properly before the first freeze, get in touch. We handle seasonal work for properties around Monticello, Lloyd and across Jefferson County.