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I have a sprinkler system that I winterize each year by blowing air to remove water. The system looks similar to the picture below.

Home sprinker System

Can I use the siphon to winterize this system if 1. I add a new shutoff valve to open/close the drain pipe. 2. Shut off water to sprinkler and open the drain pipe valve so water can flow via gravity to a sump collector (shown below)

I know this is logical, but is it practically feasible?

  • If this valve is located at a low point in the system at least the water up to the sprinkler heads will be drained. – Ed Beal Jul 31 '18 at 19:02
  • Ed, thanks for the validation! 1. Do you mean the valve, or could it just be the end of the pipe (shown in black at the end of the red outlet pipe). Will this be enough for winterizing or do I need to drain all water out like it happens when we use an air compressor? – Jersey_Guy Jul 31 '18 at 19:16
  • I see a problem if the piping outside actually goes down hill. Once vacuum gets broken because there is a head which vents the line, nothing in the line beyond that will drain. Low spots are also a problem, I actually blow my system out twice just because I know of a few problem low spots in the pipe, with a siphon you are far less control. I actually have a compressor hose fished across a ceiling to make hooking up the blowout simple, sure, probably not supposed to fish hose in a ceiling, it’s only hooked up a few hours in the fall. I’d sure try to stick with a blowout method if you can. – Tyson Jul 31 '18 at 19:48
  • Several properties I have owned were on a grade so I put a drain valve in at the low point , most of the water drained out not all but getting the water well below the surface has worked for me but it rarely gets below the mid teens and never more than a week so the branch lines don't freeze and all the pipes going to sprinklers are dry. – Ed Beal Jul 31 '18 at 19:51
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It's not a great idea. One big problem is that you'll probably siphon very little of the total volume. If you try and drain multiple zones at once, all of the siphons will break once the shortest zone starts admitting air. If you go one at a time the siphon will probably break once the pipe contains an air/water mix.

The other big problem is that you're likely required to have a backflow preventer separating the irrigation and potable water system. If it has to be outside the building, you're dead in the water. If you already have one outside it's plumbed in at the highest point. There's no guarantee any siphon would be enough to pull water back over the hump even if you remove the valve. Remember, the line from the zones to backflow preventer would be filled with air after the first zone drained, so you'd have quite a lot of empty pipe to the second zone. (Which is probably long enough to just let the water fill the bottom half of the total length and not create a siphon at all.)

Assuming things did work it'd be extremely slow because the heads will remain shut and restrict venting. You'll be creating a vacuum, as opposed to the compressor which adds pressure and pushes the heads open. Even if it was all downhill rather than a siphon you'd be in a gravity vs vacuum fight.

In the absolute best case where you changed everything so it was draining downhill and installed removable caps top vent the ends of each zone you would have succeeded in constructing an efficient method of moving water from the lawn into your basement. That's not going to improve your property value much.

  • - Siphoning little of the total volume: I would start with the longest zone and work down to the shorter ones. Need to test the break for air water mix, as I have seen siphons work out small breaks due to water pressure. - Backflow preventer: Already present and is inside the basement (shown in the diagram) during home build. - Speed is not an issue as I got time - Moving water into basement, it goes directly into a sump as shown in the figure. I would use this and set up the normal air blow as a backup the first year, will come back with an update in a few months on how that went. – Jersey_Guy Aug 2 '18 at 12:36

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