This time of year in neighborhoods throughout Kansas City many outdoor do-it-your-selfers are taking time to winterize their lawn and landscapes, and sometimes tackling the winterizing of their own lawn irrigation systems. It can be a much bigger project than one might think, as there are a lot of things to 
consider when taking on the task of shutting down irrigation for the winter. Heinen Landscape & Irrigation doesn’t recommend this project for the average homeowner, but we’ve put together a few tips if you’re feeling handy!
The first thing you need to do is shut off all the water supply to the irrigation system. Switch your valve to “rain mode,” this shuts down the signals to the valves. Next, you need to remove the backflow preventer, any water from the risers, and then cap them. You can use a wet/dry shop vacuum, but you might need to rig a smaller hose to it, as the vacuum is usually too large to fit. Then drain the water and put it in storage for the winter.
While on the topic of backflow preventers, if your irrigation system was installed correctly, your backflow preventer should also have permanent insulation. This protects from any unexpected freezes late in the season. These types of freezes are usually on the lighter side, so insulation should be enough to keep you from replacing those expensive backflow preventers!
Next is the main event – evacuating all the water from the pipes so they don’t burst. You can do this one of two ways: 1. Drain the water through the valves or, 2. Use the blow out method. The blow out method is generally recommended but it can be a little tricky for the average person. The general problem with the blow out method is that if done incorrectly, your irrigation system can easily be turned into a multitude of buried shards of plastic.
Here are a few suggestions to do it right. First you’ll need a BIG air compressor if you want to successfully blow out your pipes. It likely needs to be bigger than the small compressor many people own for tasks like inflating bike tires or sport equipment. Irrigation experts recommend at least 20 cubic feet per minute for a small system (with ¾ inch PVC pipe or 1-inch poly pipe). Most experts recommend 50 cubic feet per minute for a home irrigation system. Each irrigation system is different, and it might take a little research to find just the right air compressor.
Step by Step Sprinkler Shut-Down Guidelines:
Every system is a little different, these are general guideline. Get to know your own system before attempting seasonal shut-down or repair work.
Be sure to connect the air compressor to the backflow preventer riser (on the downstream side). If you
blow air through the backflow preventer or through a pump, you could damage them! Air reacts differently than water inside the pipes, so always wear protective goggles and turn the air pressure up slowly.
It is important that the air compressor has a pressure regulator valve with an accurate gauge on it. Do 
not turn on the compressor yet! If you have anti-siphon valves you’ll skip this step (but don’t skip the warnings).
Safety first. Plastic pipe is not designed to hold compressed air. Put on eye protection and keep everyone away from the sprinkler heads. If the air becomes trapped by a pocket of water in the pipes it can suddenly “burp” free with enough force to explode the sprinkler heads. Always increase the air pressure in the pipes slowly. Never attempt to blast out the water with a sudden burst of air. If you can’t get the water out with a steady flow of air, then you need a higher capacity air compressor.
Using the automatic controller (timer), turn on the last valve that is furthest from the backflow preventer. Only turn on one valve at a time. If one valve is considerably higher in elevation than the others you may want to start with it rather than the last valve, but in most cases the last valve is the first one you should blow out. If you have manual valves, just open the valve manually. If you have anti-siphon valves (which you removed earlier), you will not be able to open the valve (because you removed it), so instead you will now need to hook the compressor hose up to the downstream side of one of the valve risers.
Turn on the compressor and slowly increase the pressure. Carefully monitor the air pressure, never allowing the pressure in the irrigation system to exceed 50 PSI. You probably won’t need 50 PSI to blow out all the water – the lower you can keep the pressure, the better. Watch the temperature also. Air heats up as it is compressed. The air can be very hot when it leaves the air compressor, hot enough to melt the plastic sprinkler pipe. It may be necessary to add some extra length of hose between the compressor and the connection to the sprinkler system so the air can cool a bit before entering the sprinkler system piping.
Allow the air to run until all the water is blown out and only air is exiting through the sprinkler heads. Don’t blow air through the system any longer than necessary. If it takes more than 2-3 minutes for the water to get out, stop the compressor and let everything cool down for a few minutes, then start again. Be patient! Keep watching that pressure and temperature. The first valve will probably take a lot longer to blow out than the others because most of the water in the mainline pipes gets blown out of the first valve zone.
After only air is coming out of the sprinklers, turn off the air compressor, and then turn off the valve. Open the next valve, turn back on the compressor and repeat the blow-out procedure. Continue until all the valve circuits have been blown out. Note that if you have anti-siphon valves you will need to switch the compressor hose to the next valve riser.
Never turn off all of the valves while the compressor is still running. A valve must be open at all times. The goal is to blow OUT the sprinklers not blow UP the sprinklers.
When all the valves have been blown out it is a good idea to repeat the entire process again, starting with the first valve.
If you have a mainline section upstream of the backflow preventer that you are planning to blow the water out of, now is the time. Hook up the compressor to the blow out fitting just downstream from the irrigation system shut-off valve and blow the water out through the backflow preventer riser.
Put the automatic controller into “rain mode” when you’re finished blowing the system out. (Or you can turn it off if you wish.) Install threaded caps over the open ends of the backflow preventer risers, anti-siphon valve risers, and any blow out fittings to keep garbage and insects out until spring. Store the backflow preventer inside for the winter.
See more tips at irrigationtutorials.com.
Need Help? Call a Heinen Irrigation Professional
We don’t recommend this project for the average DIYer. If you’re feeling a bit over your head on this project, call Heinen Landscape & Irrigation today for a no obligation sprinkler inspection 
visit along with a low cost sprinkler system winter shutdown. We’ll have one of our irrigation experts out there in no to winterize your irrigation system.
We’ll also give you an estimate so you can plan any updates to your system for the spring – includingoptions like water-saving sprinkler heads and even smartphone sprinkler controller apps that can save you water and money. We can also add on to existing sprinkler systems – with additions for your garden, shrubs or other foliage areas. And, if you are flexible on timing, you can save on system repairs or upgrades made during the warmer days of off-season winter months. Just call Debbie at Heinen Landscape at 913-432-5011 to get an inspection, an upgrade estimate or winter sprinkler shutdown appointment today!
