wintercouponHere in Colorado it is important to winterize your sprinkler system in the month of October. Some early birds will winterize at the end of September. That does not hurt anything but may have you doing some watering by hand. Which completely eliminates the risk of freezing. Just make sure you disconnect the garden hose.

During the month of October your lawn typically will require less water for many reasons but mainly because we have less heat and evaporation. We still can have some hot days and that is why so many people want to leave their system on until the end of the month. The rule of thumb is that every day you wait to winterize in October is an increase in the risk of freezing. If the temperature drops down to 32 degrees, there is a chance you will have a break in your vacuum breaker. Every November I have a few stragglers that put off winterizing and got away with it. At the same time I’ve done many freeze repairs in Octobers past.

How do I get my system to make it through October and into November? First of all grass is going dormant by then so it may not matter. If you cover you Vacuum Breaker with insulation and a plastic bag it will help keep it warm. Keeping the air and moisture off the unit will help prevent freezing but is not guaranteed. An over night freeze is not going to freeze valves that are below ground. Some systems have a curb stop valve and a double check vacuum breaker which may also be below ground in a box. These systems are protected from over night freezes but very expensive to install.

Some systems can be drained while other systems require the water to be evacuated from the pipes to prevent freezing. This creates a lot of confusion for people especially when someone tells me they never do a blow out. Fact is that the ground will develop frost 4 feet deep in a cold winter. Water expands by about 11 percent. In order for a sprinkler system to be safe the pipes can not be near full of water over the winter. Auto draining systems tend to have problems with the drains; then I repair them all summer long as well as pipes that have probably frozen in the past. If you have a self draining system make sure you drain your tap, manifold and run the valves for a minute or two with the water off to activate the drains in your zones.

A big cause of freeze damage occurs when the main shut off valve leaks. The valve may leak one drip at a time right back into your system after you have drained it. The only way to know about this is to have a freeze or by double checking your tap drain 30 days or so after you have drained it. If water has magically filled the pipe you know your valve is not fully off or it is leaking. If you had a freeze last year after having a proper winterization, check your tap drain in November this year. If there is water in the pipe replace your tap valve.

Call me and we’ll walk through it together.

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My customers call me and ask, “Dave, is it safe to turn on my underground sprinkler system now?”.

Here in Colorado I have seen temperatures drop below freezing as late as June. Of course that is extremely rare. However it is not uncommon for Colorado to drop below freezing over night during April and often times, early May. That is all it takes to cause some fairly expensive repairs.


If it is a dry season, with little rain or snow, I recommend using the garden hose to keep dry spots green during the month of April. It is rather inconvenient to drag that hose around, I know,  but start watering late April or early May. Because we tend to have the temp drop below 32 degrees in the month of April, once your system is activated there is still a slight chance we could freeze in May. So it is best to insulate your vacuum breaker or back flow prevention device. You can do this by wrapping it with old towel, rug or insulation (best choice) then cover that with a plastic bag. This will reduce the risk you take of freezing. It only takes 32 degrees for a short period of time to crack the popet and bonnet kit in your vacuum breaker. As soon as it thaws out is when you have the water running down the street or into your basement.

Having your system wrapped will keep the ambient air from getting to the water in the pipes and reduce the chance of freezing. The best way to prevent freezing is to actually drain the vacuum breaker and manifold system. You can do this by turning off the main valve normally located in the house or at the curb. Then go over to your vacuum breaker and you may have a pea drain where the copper pipe comes out of the wall. Open that and let the water flow out. If not, open the drain inside the valve in the ground. Sometimes this in an automatic drain that you can not open or you have to unscrew a cap. Many systems have a drain that can be opened with a key or wrench at the end of the manifold. Use a screw driver to open one of the small test ports on the side of you vacuum breaker to create an air gap. Otherwise the water will not come out, just like when you open one side of a can with a can opener. Next go back into the house and open the drain valve or pea drain located on the turn on valve. This will get the water out of your pipes that are exposed to the cold weather.

Some systems are auto draining as indicated above. In that event turn off the main valve and run a short manual cycle of each zone. This will open the automatic drains and allow the water to seep out. You will need to open one of the small valves on your vacuum breaker to allow air into the system. Now you should be able to drain the water from the vacuum breaker by going back to the main turn on and opening the drain located there. You will now be protected from freezing and it only takes a few minutes but can save hundreds of dollars in repairs.

by, Dave Ferdon, Owner Operator of Thornton Sprinklers.

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