Why Draining the Main Line Is Not Enough

A commercial irrigation system holds water in more places than the main supply line. Valves, lateral pipes, sprinkler heads, fittings, and backflow equipment all retain water. When that water freezes, it expands. The results — cracked piping, broken heads, leaking valves, a damaged backflow preventer — may stay hidden until the system is activated in spring, when repairs add unexpected cost and delay seasonal landscaping.

The most common cause of missed winterization is not neglect. Two parties each assume the other is handling it. The property manager expects the landscaping contractor to schedule the service. The contractor assumes the manager is coordinating it. Nobody makes the call. The first hard freeze does.

This week’s article covers what a proper blowout involves, what it costs, and how to make sure responsibility is assigned before the window closes.

1. Confirm the appointment in writing today.
Get a specific date, scope of work, and price. Providers fill up quickly during the fall rush. If you lack written confirmation, call this morning.

2. Assign responsibility before the season ends.
Confirm who is handling the blowout, when it is scheduled, and whether the scope includes all zones, the backflow preventer, valve boxes, and controller shutdown. Keep it in the property’s maintenance records.

3. Verify what the services includes.
A complete commercial blowout clears every zone with the proper compressor capacity and addresses the backflow preventer. Skipped zones or inadequate pressure can leave water behind. Confirm the scope before the appointment.

The commercial properties in DuPage County that activate their irrigation systems in April without incident share one habit: they treat winterization as a confirmed, documented service, not an assumed one.

A written scope of work. A service date confirmed before October ends. A record filed with the property’s seasonal maintenance documentation. When something does fail over winter, that paper trail determines whether the cost lands on the vendor’s insurance or on the property’s operating budget.

The documentation discipline extends to the exterior surfaces that surround irrigation infrastructure. Hardscape, concrete, and pavers that go into winter with organic buildup and surface contamination give freeze-thaw cycles more to work with.

Q: “Can our facilities team handle the irrigation blowout in-house, or do we need a contractor?”

It is possible to do in-house, but easy to do incompletely and incomplete is the problem.

The compressor must match the system. Too little air pressure and water stays behind in low spots and lateral lines. Too much pressure and you damage heads and valve components. A licensed irrigation contractor knows the right CFM for your system size, works zone by zone until each section is properly cleared, and can identify components that need attention before they become spring failures.

For smaller systems with straightforward layouts, a knowledgeable facilities team with the right equipment can manage it. For multi-zone commercial systems with longer pipe runs, a backflow preventer, and zones with varying elevations, a professional is the lower-risk call.

Either way, the scope and completion should be documented. “We blew it out” is not a maintenance record. Zone-by-zone confirmation with a sign-off date is.

Winterization protects underground irrigation lines, but nearby concrete, pavers, and hardscape need attention too. Removing organic buildup before freeze-thaw weather helps limit moisture damage, cracking, and spalling.

In DuPage County, the pressure-washing window typically closes in mid to late November, when temperatures stay below 40°F. It is still open now.

Know a property manager who is still assuming the landscaping contractor handles the irrigation blowout? Send this before the first hard freeze does it for them.