How to Drain the Basement Pipe of a Sprinkler System

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If you were not home during the sprinkler blowout service or you want to drain the sprinkler system's pipe prior to our arrival, please follow the instructions below very carefully. Please note that if you skip any steps in the process your sprinkler system might have damage the following spring. The following is how to drain the sprinkler system pipe for winter.

How To Drain The Basement Pipe of a Sprinkler System

Step #1

Turning off the water to the sprinkler system

Go to wherever the water shutoff to the sprinkler system is located. This is typically downstairs in the crawlspace or basement. Find the sprinkler shutoff valve, this valve could be a lever (ball valve- Illustration B) or a thing to twist like your outside spigot (gate valve- Illustration C).

If it is a lever (Ball Valve) turn it until the lever is perpendicular with the pipe. With ball valves perpendicular to the pipe always means the valve is closed and parallel with the pipe always means the valve is open.

If the valve is a gate valve (C) please turn it clockwise to close the valve. If you have a gate valve (C) you need to turn it as hard as possible because they can often leak water if they are not completely closed.

Please note that there may be many pipes in the basement and figuring out which one is for the sprinkler system can be a little confusing. If you are not sure where your sprinkler shutoff valve is located you should first find the vacuum breaker (pipe structure outside –Illustration A) and trace the pipe backwards until you reach the first valve. This is your sprinkler shutoff valve.

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Ball Valve

This is a ball valve. This is what a basement pipe sprinkler system shutoff usually looks like.

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Gate Valve

This is a gate valve. To close this you need to turn the handle area all the way clockwise until it stops moving. Then you need to turn it very hard to make sure it is 100% closed.

Step #2

Verify the water to the sprinkler system is off - not the water to the house

Make sure that you have turned off the sprinkler shutoff valve and not another water valve. You should turn the water on at your kitchen sink and the sink water should still be flowing; if the sink water is not flowing, you have shut off the main water to the entire house. If you have shut off the water to the entire house, go back and turn off a different lever until you turn off the correct lever. After you turn off the correct lever, mark it "sprinkler shutoff" so the following year you know exactly what lever will shut off the sprinklers.

Now that the sprinkler water is off, you need to go outside and find the vacuum breaker, which is pictured to the right (this can be in the front, back, or either side of the house).


Step #3-A

Draining the sprinkler system pipe if the sprinkler system has already been blown out

If we have already blown out the sprinkler system, one of the valves on the vacuum breaker will be at a 90 degree angle (perpendicular or shut). The other valve will be left at a 45 degree angle.

Only after you have turned off the water should you turn the other valve to a 45 degree angle. If you open the lever that is at a 90 degree angle prior to turning off the water, then you will let water into the vacuum breaker and we will need to come back to blow out the system again.

The lever that is perpendicular and closed will will be on the pipe coming directly from the house. Turning the valve at a 45 degree angle will allow airflow into the basement pipe. It is very important to open the air flow to the system because without opening this air flow, the basement pipe will not be able to completely drain.

Note: If water gushes out of the test cocks then you have not shutoff the correct valve in the basement. If water is gushing out from the test cocks, close the valve back to a 90 degree angle (closed) until the water stops and please contact our office. We will need to blow out the system again because water probably got into the vacuum breaker.

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Vacuum Breaker

Step #3-B

Turning off the water and draining the pipe before the system has been blown out

If you are draining the water in the basement pipe prior to our arrival then the lever will be parallel (open) to the pipe. You can either leave this lever open or you can put it to a 45 degree angle, but do not shut it or put it at a 90 degree angle. Leaving it open or at a 45 degree angle allows air to flow into the basement pipe and will allow the water to drain properly.

The test cocks will be closed on the vacuum breaker (perpendicular). You will need to open both of the test cocks by using a fathead screwdriver to turn the screw on the side of the test cocks so they are open. To do this turn them 1/4 turn so the flathead screwdriver line is parallel with the test cocks. If you are not sure how to do this just turn the screw 1/4 of a turn. It is important to open the test cocks because if they are closed no water will drain from the basement because there will not be any airflow in the pipes.

Note: A little water will gush out of the test cock and then stop, this is normal. If it continues to gush then you have not shutoff the correct valve in the basement. If water is gushing out from the test cocks, close it back to a 90 degree angle (closed) until the water stops and go back downstairs and try to find the correct sprinkler shutoff valve.

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Test Cock or Pet Cock

Step #4

Draining the water from the basement pipe into a bucket

Go back downstairs to the sprinkler shutoff valve. Take a bucket with you so you don’t make a mess with the water.

Between the sprinkler shutoff valve and the vacuum breaker there should be a water drain nipple. This usually is a small nipple (see arrow to the right) or occasionally a spigot drain just like your outside hose spigot. After you find the drain, put the bucket up to the drain nipple or spigot and unscrew the nipple or open the spigot and drain the water. Do this until all the water is completely drained from the pipe. If no water drains please see the note below.

If the pipe stops draining water then you are finished.


What to do if the water doesn't drain from the basement pipe.


Note: If no water comes out of the pipe this means you have a vacuum lock because there is no airflow in the pipe. You have either not opened the lever #2 to a 45 degree angle or the test cocks are closed. Close the water drain nipple and go back to the vacuum breaker and either open lever #2 or open the test cocks and try again. If this does not work please contact our office for advice.

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Drain Nipple

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