About 25 years or so ago I had underground sprinklers installed in my house and since the contractor said he had to call a plumber to install the required ball valve and backflow preventer shown in my pictures(I think that’s what you call this fitting) I offered to install these fittings myself and all worked fine for about 5 years and the contractor will come every Fall to blow the system dry. Then City Hall banned the use of these sprinklers for water conservation and I stopped using the sprinklers since.

However every Fall I have to cut the water to outside two hose bibs I have to prevent water freezing. In the front hose bib shown in the picture here, I shut the ball valve from inside the house and then I open the drain valve inside the house + the one outside and let the water drain completely. The next day I shut off the exterior hose bib to prevent anything going into it but after a few days when I open that hose bib there is lots of water, with some pressure, coming out again. The picture you see of the exterior hose bib I had this valve closed last week and today when I took the picture I opened the valve and water splatter all over the wall and floor and its visible on the picture. Then the water will stop coming out and eventually will stop. I will estimate the water coming out is about 1/2 gallon.

When the ball valve is shut and the sprinklers have been dead for years where all this water come from?

 

kolias -

Need the plumbing gurus to weigh in here, but it would seem that the ball valve is not closing completely. But – I guess that doesn’t sound right because I thought that ball valves really don’t have that problem like gate valves do. That’s’ one of the reasons they are better. Head scratcher here.

 

I also suspect the ball valve is leaking. Leave the inside drain valve open with a bucket under it and see if you get water in the bucket.

 

Turn the ball valve off.
Open the drain valve..... and leave it open.
Hang a pail under the drain valve and see if it stops.

Is the "underground sprinklers shutoff" valve turned off ?
If you aren't using the sprinklers you could leave that valve closed and the sprinkler system empty.
There wouldn't be a need to blow the sprinklers out every year.

 

PS, that is not a proper back flow preventer, maybe a check valve, but not a legal backflow preventer, just saying!

 

Never thought a ball valve will leak but I will give it a try and put a bucked tomorrow and see the results. The ball valve is B&K, 150 WSP, 600 WOG.

The “Back flow preventer” is not what I guessed but instead it is a Dual Check Valve #7, ASSE 1024.

The underground sprinkler system has been dead for many years and with the water conservation bylaws we have here I don’t think it will ever been used again.

In any case if the ball valve leaks it must have been full of water during the past winters and I was thinking how come the pipe never got broken with the minus 35F we get here during most of the winters.

 

I would have never thought that a ball valve will ever leak but mine she does. Last night I put an 8” diameter round bucket under the inside drain and this morning I had about 1” of water inside. As a last thought I turned the valve handle a few times ON/OFF in case it loosens up any debris inside and will give another test today.

Thank you folks

 

I understand if ball valves are soldered while closed, there is some plastic inside that can melt and cause issues. I've never run into this myself, but I was taught to always keep ball valves open while soldering.

 

Thanks for the input, I install this valve myself some 15+ years ago and I know no matter which valve you solder, she must always be in the open position. In some you may also remove the stem.

The problem now is long ago I was much younger and able to do the job but now as we age, I don't feel up to the task and finding a good and honest plumber is almost impossible. But have to do it before the winter comes!

 

Since that valve is just leaking through and not leaking outside its body, leave it open in place. Add another valve in the horizontal or vertical piping beyond the check valve. Depending on how much you can move the existing piping consider using a Sharkbite valve.

 

I didn't know about these valves but searching in my local HomeDepot looks they are available and I will investigate. Some they have one threaded end and dont know why. My pipe is 3/4" so I hope they come on that size too.
Thanks for the heads up