Irrigation Winterization Before the First Freeze: A Grounds Crew Checklist

October 29, 2026

Grounds crew inspecting an irrigation valve box and backflow assembly before freezing weather

When a forecast starts showing freezing nights, the irrigation system deserves its own shutdown plan. Water left in piping, valves, sprinkler heads, pumps, or backflow components can freeze, expand, and damage parts that looked fine at the end of the mowing season.

A useful irrigation winterization checklist is less about racing the thermometer and more about working methodically: identify the system, record existing problems, follow the equipment instructions, and keep unqualified workers away from pressurized-air work.

Start with the site, not the compressor

Walk the property while the system can still be operated normally. Bring the zone map, controller schedule, valve-box key, marking flags, and a simple inspection sheet. Run one zone at a time if conditions allow, then note:

heads that do not rise, retract, or rotate correctly;
leaks, low pressure, uneven spray, or water collecting near valve boxes;
damaged lids, exposed wiring, cracked fittings, and sunken heads;
drip zones, hose connections, pumps, filters, and other components that need separate instructions; and
landscape changes that no longer match the old zone map.

This is the last easy chance to separate a pre-existing repair from possible winter damage. Take clear photos and put the problem on the spring work list instead of trusting someone to remember it months later.

Identify how this system is supposed to drain

Irrigation systems are not all built the same. Some use manual drains, some use automatic drains, and some require a compressed-air blowout. Climate, pipe material, layout, backflow equipment, and manufacturer requirements all matter. A method that fits one property may be wrong for the next.

Before touching valves, locate the irrigation shutoff and confirm that it is separate from the building's domestic water controls. Review the installed equipment manuals and any local requirements for backflow assemblies. If the crew cannot positively identify the system type or safe connection point, stop and bring in a qualified irrigation professional.

Shut down the water in a controlled order

Follow the system-specific shutdown procedure. That normally begins with closing the irrigation water supply, relieving pressure through the correct zone or valve, and draining components in the order specified by the installer or manufacturer. Open pressurized drain valves slowly and wear eye protection appropriate to the hazard.

Do not treat the backflow assembly like an ordinary pipe fitting. Manufacturer guidance may require particular isolation-valve and test-cock positions, and some assemblies must not have compressed air blown through them. Above-ground backflow equipment and valves may also need insulation that leaves required air vents and drain outlets unobstructed.

Record the final valve positions on the work order. A photo helps the spring startup crew understand exactly how the system was left.

Handle the controller according to its manual

A controller's winter setting is model-specific. Some manufacturers provide an OFF or rain mode that stops watering while preserving time and programming. Other models have different power or battery instructions. Pumps and master valves can add another layer of risk if a controller is accidentally activated after the water supply is off.

Use the manual for the exact controller on site. Label any wires that a qualified person disconnects, close weather-rated cabinet doors, and leave a dated tag stating that the irrigation supply has been shut down. Avoid a blanket rule such as “always unplug it” or “always leave it powered.” The correct choice depends on the equipment.

Treat compressed-air blowouts as specialized work

A blowout is not just air cleaning. It introduces stored energy into a piping system that can eject water, debris, or failed components. Hunter Industries recommends that a qualified licensed contractor perform this method, warns workers to wear approved eye protection, and says no one should stand over pipes, sprinklers, or valves during the operation. Rain Bird likewise recommends professional help because of the safety risks.

If trained personnel perform the work, they should use the manufacturer's procedure for that exact system, select equipment by required air volume, regulate pressure below the lowest-rated component, keep bystanders clear, and use short cycles instead of running air through dry piping. Hoses, couplings, and the connection point should be inspected before use. Never aim compressed air at a person or use irrigation blowout pressures as a general cleaning setting.

There is no responsible universal pressure number for every property. Pipe material, zone design, fittings, sprinklers, and backflow arrangement change the limit. When the specifications are missing, the job is not ready to proceed.

Do not forget the small exposed parts

After the main system is handled, walk the perimeter again. Disconnect and drain hoses. Check outdoor faucets, quick couplers, exposed PVC, filters, pump housings, and above-ground drip components. Follow the manufacturer's storage or insulation instructions for each part.

Look down into valve boxes for standing water, damaged lids, or soil that has settled around piping. Do not reach into a flooded box until electrical and other hazards have been assessed. Fixing drainage around the box may belong on a separate work order.

Close the job with a spring-ready record

A complete winterization record should list the date, property, crew or contractor, system method, zones completed, controller status, shutoff location, final valve positions, known defects, and any components removed for storage. Attach photos of the controller, backflow assembly, shutoff, and problem areas.

Tag the controller with three short notes: water off, winterized, and inspect before spring startup. Store specialty keys and removed parts in a labeled location. The goal is to make spring startup a planned inspection, not a guessing exercise.

A practical crew sequence

Review the forecast, site map, manuals, and local requirements.
Operate and inspect each zone while normal testing is still possible.
Document leaks, broken heads, damaged boxes, and landscape changes.
Identify the shutoff, drain method, controller, backflow assembly, and safe service boundaries.
Shut down and drain only according to the system-specific procedure.
Use a qualified professional for compressed-air work when training, equipment, specifications, or authority are missing.
Inspect exposed components and record the final condition.
Tag the controller and build the spring repair list.

Finish the shift ready for tomorrow

Cold-weather grounds work is easier when the shutdown is organized. Dry wet gloves, inspect eye protection, clean and store the tools, and restock the truck before the next property. For a broader cold-weather routine, see The End-of-Day Winter Work Reset.

After the tools are put away and hands are clean, Work Putty Unscented can be one part of an after-shift skin-care routine. It is not freeze protection, PPE, or a substitute for gloves and safe work practices.

SHIFT SHIELD™ is worker protection built for everyday workers by everyday workers. Read more practical field guides in The Daily Blog.