Winterize Sprinklers

Available only as part of a year round maintenance plan.

Winterizing sprinklers protects the sprinkler system from the affects of frost during winter months. Not every landscaper in Portland, Oregon is equipped to properly winterize your sprinklers, also known as sprinkler system blowout. If water in the sprinkler system freezes during cold weather, it can cause cracks in the pipes and break other parts of your irrigation system.

The problem—broken pipes and vacuum breakers

During periods of extreme cold in the Portland, Oregon metropolitan area, cold air blows out of the Columbia River gorge. This frigid air affects not only the Troutdale/Gresham area but also all of the Portland, Oregon metropolitan area including even Happy Valley and the Lake Oswego area. As the wind continues to blow, the frost penetrates deeper and deeper into the soil.

When water freezes and changes to ice, it expands. This expansion is the real problem. If the depth of the frost reaches the sprinkler system components, the expanding ice may cause cracks in various parts of the sprinkler system.

The most commonly affected parts are those that are above ground. Yes, some sprinkler systems do have above ground parts that readily break when frozen. This includes both galvanized and PVC pipes and fittings, as well as any anti-siphon device that is located above ground. We commonly do repairs on these items every spring. If you have above ground sprinkler components, winterizing your sprinkler system annually will almost certainly save you money.

Underground sprinkler parts may be affected as well, however. After many years of experience we have found that it really comes down to localized environmental factors. For example when underground plumbing is near a retaining wall, the cold air comes from both the top and the side. Thus it penetrates deeper and further.

The solution—evacuate the water

We use an industrial air compressor that is built into our irrigation tech truck coupled with an extra large reserve air tank to push the water out of the pipes with compressed air. Hence the term—blow out the sprinkler system. A small air compressor really does not work so well since the available volume of air rapidly dissipates. What counts is volume of air and not pressure. In fact rumors abound in landscaping circles about broken pipes when someone does a sprinkler system blowout with high pressure.

Think of it as a long P-U-S-H of air. It has to travel through the mainline to the valve and then to the various parts of the sprinkler zone. Once air begins to escape sprinkler heads, the resistance decreases rapidly and the supply of compressed air diminishes quickly. This air typically must passes through numerous sprinklers simultaneously. That’s why we use a high volume industrial air compressor along with a large reserve tank. This combo has high pressure but a pressure regulator reduces the psi to safe levels.

Removing all the water is not possible, at least not from a practical standpoint, but it also is not necessary. A little left in the lowest areas seems to be of little consequence. By using an air compressor that supplies high volumes of air, you can watch the earlier sprinklers blowing mist while those further down line still blow and spit out water. We wait until all the sprinklers are blowing mist which indicates that most of the water is gone.


  • Typical residential and very small commercial: $55.00. Special circumstances may result in a higher fee.
  • Larger residential systems and most commercial systems will be priced individually.
  • We must have access to the anti-siphon device and preferably the sprinkler controller (clock). If the latter is not accessible we can usually manually activate the valves. However, you must supply specific instructions about where all the valves are located. If you email us a digital photo of each valve box, that should suffice.