Hi all,

I've recently noticed a valve leaking water outside of my house (side of garage behind a shrub) and am unsure what it is. It looks like the water pressure relief valve from the water heater. I know it doesn't belong to the water heater because the water heater relief valve directs the water line to drip water to the bottom of the water heater area. If I turn the main water city line off, the leak stops. However, shutting the cold & hot water line from the water heater doesn't do anything. I have included a picture of this leaking valve. Does anyone know what its function is and how should I go about resolving the problem? Thanks!

Hi Khoi...

Do you have a lawn sprinkler system? If so, then most likely that is a vacuum breaker and is defective and will need to be replaced. Here, you can't just cap the line as the VB acts as a backflow preventer to the sprinkler system and keeps dirty water (pesticides, etc.) from entering your drinking water system... ;)

If you don't have a lawn sprinkler system then maybe you have a pool or small pond that requires this valve?

Either way, there should be a shutoff to isolate the system (look near water meter or pump) and you can then remove the valve, take it to a local plumbing supply store and get a replacement, OK?

Good luck!

Mark

Mark,

Thank you for your answer. Is the vacuum breaker a part of the backflow preventer, between the 2 shut off valve handles on the backflow preventer? Would shutting down the valve handles on the backflow preventer a good way to stop the relief valve leak as part of the dianostic process? Thanks!

The vacuum breaker IS THE BACKFLOW PREVENTER...

Where are the two handles you are talking about?

If this is for a lawn sprinkler then you should have a main shutoff valve going to the sprinkler system. Shutting that shutoff will stop the flow of water. Replacing the vacuum breaker will stop the leak.

Back to you...

Please answer Marks question.

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Do you have a lawn sprinkler system?

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You have asked,

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Is the vacuum breaker a part of the backflow preventer,

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Not the picture you put up. There's no Plastic in a backflow preventer , (see image)
Your picture sure looks like a vacume breaker to me. Follow Marks advice.

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Would shutting down the valve handles on the backflow preventer a good way to stop the relief valve leak as part of the dianostic process?

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Shutting down the valves on the backflow preventer would cut the volume of water entering your house. I think Mark pretty well nailed it. Replace the vacuum breaker and the leak goes Bye-bye. Good luck, Tom

Mark & Tom,

Thank you for your feedback. I'm pretty novice about plumbing and I unfamiliar with the related terms. I think I misread Mark's original answer. I had thought when you said the vacuum breaker is bad, you were referring to the vacuum breaker that's part of the backflow preventer hence my question regarding shutting off the two handles on the backflow preventer (image).

Yes, I do have a sprinkler system in my yard. I have just shut off the two handles as an attempt to temporarily stop the leak but it failed to do so. The only way I know to temporarily stop the leak is turn off the main city line to my house at the water meter. Are you saying the leaking part itself is called the vacuum breaker(image)?

I was at homedepot and the guy there recommended me this item(image) as a replacement part. However, it is called a pressure relief valve, not a vacuum breaker. Did he provide me the incorrect part? Doing a visual comparison, they both look about the same except for the top/cap part. It looks like I may have to cut the white plastic tube coming out of the ground to replace because the metal piece is tighten on pretty tight and it looks to be sealed off with some type of glue.

Thanks,
Khoi

The picture of the lawn sprinkler vacuum breaker with the shutoffs is the vacuum breaker used in my area as well so that is definitely NOT a vacuum breaker leakingon the lawn!

Different states do things differently, so I will be glad to know what this is all related too?? For now, the home depot guy could be right and this is a pressure relief valve, but pressure relief valves are SAFETY DEVICES that don't usually just poke up out of the ground all "willy-nilly", so to be extra safe here I would have you shut off your main water supply valve and then take the defective valve over to a plumbing supply store and let them confirm the valve replacement choice.

See if you can unscrew the valve... look for threads. Use two pliers or wrenches and hold the plastic/metal fitting and then the valve and see if it unscrews. If not, it looks like CPVC pipe/fittings there... you will need to cut the pipe and then buy the proper valve, fittings, teflon tape and cement/primer at the local plumbing supply house to put things back together. Bring the pictures with you and all should go pretty smoothly!

Mark

Mark,

I had to cut the pipe since I couldn't unscrew it. I followed your advice on putting it back together with CPVC fittings. The leak has stopped! While purchasing the parts today, I was told that the leaky park is a pressure relief valve for the city water line going into my home. Thank you for all your help.

Khoi

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I was told that the leaky park is a pressure relief valve for the city water line going into my home.

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Mark,
Does that sound right to you? Silly me! Here I always thought PRV's were used. They now use a pop-off valve? So what happens when the city pressure's too high. Does the pop-off open up and spew city water until the pressure goes down? It just doesn't make sense to me. Of course I've been retired for 22years and lots of new stuff comes out of the woodwork. I learn from you other experts about the new stuff. So, fill me in. Thanks, Tom

Im curious about this also. Is this common in many areas, or is this extremely uncommon?

A couple of guys at the HomeDepot plumbing area didn't know what it was either until the another showed up and told me where to find the part. The part was located in an isolated area. I was told that this is not common in homes. My house was built in 2005.

You know... pretty rare that someone comes in and stumps all of us, huh guys?? I mean, if you include Tom, MGD77 and me (we won't include the other guys/gals that haven't posted to this thread at this time) we have about 100 years of experience combined and none us have come across this so I have to figure this is ULTRA-RARE, for sure!

Thanks for taking the time to pop back in and update us like you did, Khoi... that is always appreciated!

You definitely have raised our curiosity and I'll be checking into this a bit as it is different than the norm. and that's always fun stuff to research! I may post back on this and don't forget that we have a number of other qualified people that will be posting over the next week or so so be sure to check back in once in awhile, OK?

Glad you are all set!

Mark

Mark,

Definitely! I always love to learn. I came across this site while trying to figure out this problem. This is a great site with very helpful folks!

Khoi

Well this "very helpful folk" is still confused. It doesn't make any sense to me to install a Pressure Relief Valve that will divert the city water out on the ground during a pressure spike instead of a Pressure Reducing Valve that would control it.
Mark, do some checking and see if there's a logical answer to all of this. Cheers, Tom

You got it, Tom!