When to winterize a Tulsa sprinkler system, and what a blow-out actually does

Every fall we get calls from people who are not sure whether Tulsa really gets cold enough to bother. It does. Oklahoma winters swing hard, and it does not take a long freeze to do the damage, only a sharp one on a system that still has water sitting in it.

The physics is the whole story. Water expands by roughly nine percent when it turns to ice, and it does not care what is in the way. In an irrigation system the water is sitting inside rigid plastic and brass parts with no room to give, so the ice wins and the part splits.

What actually breaks, and what it costs you in spring

The failures are predictable, which is a small mercy. Backflow preventers are usually first, because they sit above ground where the cold gets to them fastest and they are full of brass fittings that crack rather than flex. Valves and solenoids in the boxes go next. Sprinkler heads crack at the body or the riser. Poly lateral lines split, and because they are buried you will not know until the system is pressurized in April and a section of lawn turns into a fountain.

The reason winterization is worth booking is that none of that reveals itself in winter. You find it all at once in spring, and you find it as several separate repairs on the same visit.

Why draining the system is not the same as blowing it out

People often assume that opening a drain valve and letting the system empty is enough. It is not, and the reason is that an irrigation system is not built to drain completely on its own.

The lines follow the contour of your yard, which means there are low spots and dips where water will simply sit no matter how long you leave the valve open. Sprinkler heads hold water inside the body. Valves hold water in the chamber. Every one of those pockets is a place where ice can form against something rigid, and a pocket only needs to be small to split a fitting.

A blow-out solves that by pushing the water out rather than waiting for it to fall out. Compressed air is introduced downstream of the backflow preventer and each zone is run in turn, at a controlled volume, until it is discharging mist rather than water. Done properly, it clears the pockets that gravity never would.

It is also the part of irrigation work where doing it yourself most often goes wrong. A shop compressor generally delivers the wrong thing for this job: not enough air volume to actually move the water through a zone, and too much pressure at the nozzle when it does. Excess pressure on an empty line is what blows heads off risers and scores seals inside valves, which means an attempted blow-out can leave you with more spring repairs than skipping it would have.

When to book it

The target is straightforward: after the growing season has genuinely wound down, and before the first hard freeze. In practice that puts most Tulsa winterization work in October and November.

• Do not book it in September because the yard looks done. Warm spells in early fall still ask for water, and a system that has been blown out is a system you cannot run.
• Do not leave it until the forecast shows the first freeze. That week is the busiest of the season for every irrigation company in the metro, and it is the week you are least likely to get a date.
• Peak season books up to three weeks out. If you want a specific week, ask early.

A proper winterization visit is more than the air. Every zone gets purged, the backflow preventer is protected, the valves and controller are shut down for the season, and you get a written report on the system's condition. That report is genuinely useful, because it is the one time each year somebody looks at every zone in sequence with nothing else to do.

It does not have to be a system we installed

Worth saying plainly, because people assume otherwise: winterization and spring startup are available on any system in the metro, whether Pro Sprinkler put it in or not. A good portion of the systems we service every fall were installed by someone else, sometimes decades ago.

If you have just bought a house with an irrigation system you have never run, that first fall visit is a good time to have somebody map what is actually out there. Knowing where your valve boxes are and how many zones you have is worth a great deal the first time something goes wrong.

Pro Sprinkler winterizes across Tulsa, Broken Arrow, Bixby, Jenks, Owasso, Sand Springs and the rest of Green Country. If you are not certain your system was cleared last year, it is worth asking before the first cold snap rather than after it.