Sprinkler Winterization: Local Deadlines by City

Deadlines for the largest cities

Find every covered city for your state in the list below.

Why the backflow preventer fails first

The backflow preventer sits above ground, holds standing water, and is made of brass that splits when trapped water expands. It is the most expensive common casualty of a skipped winterization, which is why our deadline is tied to the first 28°F freeze rather than the first light frost.

Draining alone leaves water behind in flat yards. A compressed-air blow-out at 40–80 psi, run one zone at a time, clears the heads and laterals that drains miss. Irrigation manufacturers and many local water utilities publish the same basic sequence; we paraphrase it and link the sources on our methodology page.

Blow-out vs. drain-down

If your system was pitched to manual or automatic low-point drains, draining may be enough. If you are not sure, treat a blow-out as the default. Never leave the compressor running on a closed zone, and wear eye protection — heads can spit grit as they clear.

Do the job on a dry day above freezing so you are not fighting ice at the valves. Insulate the backflow assembly and cap the hose bibs afterward, since those are the last exposed parts once the mainline is clear.

How we set the deadline

We use each station's probability dates for the first fall minimum at or below 28°F. The median (FP50) is the typical first hard freeze; FP10 is the early one-year-in-ten date. The published deadline is the median minus about ten days, so the work is done before the first hard freeze in most years. See the methodology page for the full calculation.

Find your state

Frequently asked questions

Other winter-prep guides

See the methodology for how these dates are calculated and their limits, and the data sources behind them.