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Installing check valve or ball valve on outdoor copper plumbing (see pic)

Our sprinkler system is supplied from a branch of our main water supply. Our home inspection noted that there is no check valve to our sprinkler system. I would like to either install a check valve( if that will be sufficient) or a ball valve. We do not use the sprinkler system and I dont want to spend a whole bunch of money installing backflow prevention.

I was wondering if this would be something I could do with a compression fitting or is it above my paygrade and would need welding.  Any suggestions would be helpful. Also, separately, I was wondering if sprinkler valves with built-in anti-siphon capabilities do not need a separate backflow prevention system. Thanks for your time!

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Posted 2015-03-04T16:47:37+0000  by bar959 bar959
I'm not a plumbing expert but I believe anti-siphon valves are required everywhere.  While they are relatively inexpensive you'll have to do some plumbing.  If you never use sprinkler system and never plan on using it, it would be easier and much cheaper to cut the pipe and cap it.

While soldering isn't difficult I can understand that some people don't want to be bothered.  Fortunately Shark Bite makes a slip on (no solder) cap fitting.  While it's absurdly expensive compared to a simple copper cap, it would work just fine in your situation.  I'm guessing that pipe is 3/4" but measure it to be sure.  The size of the pipe is the internal diameter so the outside will be slightly more (about 13/16 for 3/4" pipe).

The part number for the 3/4" size cap is U518LF and U520LF for the 1" size.

  1. You're going to want to remove about 1 1/2" from the center of the pipe.  It doesn't need to be exact but you want enough room slip the cap in there.  Don't go to either end, you want to leave a couple of inches of pipe so you have something to work with should you ever decide to reconnect the sprinkler.
  2. Clean the pipe because the fitting relies on a o-ring to seal.  If you have some 150 grit or so sandpaper around, use that.  Or you can use green ScotchBrite pad from the kitchen.  You want to clean about an inch to the left of your cut.
  3. Turn off the water supply and cut the pipe.  Use a pipe cutter and you may need one for close quarters because of the proximity of the pipes to the house.
  4. Slip on the fitting on.
  5. Turn on the water and check for leaks.

Make sure the pipe cutter will cut the size of the pipe you have:

Questions?  Let us know!
Posted 2015-03-04T23:46:49+0000  by Adam444
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