Unraveling Water Supply Routing from the Street

[Lollipop]

I'm hoping someone can shed some light on this situation. I'm in the process of lowering my incoming residential water pressure. I purchased a new +/- 1% tolerance liquid filled gauge to do this. This is a 3 year old home and the existing pressure is 74 psi. I want to lower it to a traditional 55-60 psi. I have a Honeywell water pressure regulator (D06F-XX) I'm trying to adjust. According to their instructions I must shut off the water inlet valve and open the water tap, before an adjustment can be made. I assume this is to relieve pressure from the regulator in order to be able to adjust it down. The problem I have is, what looks to be an incoming water main ball valve in an irrigation labeled box. I assume this because the box is located almost directly across from the city meter and the hose type looks identical to each other. When I turn the ball valve off, the water at the hose tap runs continuously. I initially bled off about 2 gallons. Do I need to run it for an extended period of time to purge the system? I've attached a few pic's. Maybe someone can give me some direction. I really don't want to spent $60 to have a plumber show me how to do it. Thanks

 

[Diehard]

Well it sounds like you don't have the correct valve to shut down your water service.
In your picture of the House external plumbing, is that the pressure reducing valve in white?
I can see the direction of water flow through the Pressure Vacuum Breaker feeding your irrigation system, on the right.
I could make a guess but I'm still not positive what the direction of flow is through you foundation wall. Coming out the top and going back in the bottom or vice versa.
Do you know?
My first guess would be that it comes out the top, through that SHUT OFF VALVE, tee branch of high pressure water to irrigation system, run of tee down to PRV and back into house with reduced pressure.
Where did you check your existing pressure of 74 psi?

Edit shown in red.

 

[TomFOhio]

If the water is coming from the ground up shut that ball valve off right before the backflow and see if that shuts of the house too.

 

[Diehard]

Looking at that Pressure vacuum breaker again, I see that I had the flow through that item wrong. As TomFOhio questioned the flow coming up from the ground, he would be correct as that IS the typical flow through those devices. It appears to be a somewhat different arrangement than I typically see.

So that definitely would shut of the water going into that tee EDIT: Wrong! I must have been on drugs when I said this.

 

[Lollipop]

Thank you for the replies. Last night I went over to a new development under construction and found a similar style home and confirmed water flow is from the bottom to the top. I re-attached my pic with updated detail. Both the plumbing company which performed the install and a home inspector both checked water pressure at the hose bib. This is where I checked it, as well to obtain the 74 psi. Yes, the in-line ball valve does shut off the water into the home. So to me, both the water service into the home, the hose bib, and the irrigation are all regulated via the PRV, since it is located downstream. Hope this answers your questions. What about the ball valve in the round irrigation box, which I assume is a shut off tied to the main? If I shut it off, does it take a fair amount of time for the house pressure to drain, if I open the hose bib?

 

[Diehard]

Can you see both of those 2 lines from the other side of the wall? (I assume it some type of crawl space.)

Why would a house water service valve be located in a box labelled Irrigation System?

Do you have access to the meter where I assume a valve would be located? Is it located on your property?

I'm from an area where we have our meters and shut off valves located within the homes. It seems crazy to me that the water purveyors do not require a local shut off valve. How far away is your meter and that irrigation valve box?

You say "if you turn the ball valve off at the irrigation box, the water at the hose tap runs continuously." If it was your control valve, the water would lose much of its pressure, which should be obvious. Of course, you would be getting water running back from your house piping also. You should be shutting off the next shut off valve going into house piping so that it doesn't run backwards.

 

[TomFOhio]

If you have an irrigation system then that is what that valve will shut off.

 

[Lollipop]

Can you see both of those 2 lines from the other side of the wall? (I assume it some type of crawl space.)

Why would a house water service valve be located in a box labelled Irrigation System?

Do you have access to the meter where I assume a valve would be located? Is it located on your property?

I'm from an area where we have our meters and shut off valves located within the homes. It seems crazy to me that the water purveyors do not require a local shut off valve. How far away is your meter and that irrigation valve box?

You say "if you turn the ball valve off at the irrigation box, the water at the hose tap runs continuously." If it was your control valve, the water would lose much of its pressure, which should be obvious. Of course, you would be getting water running back from your house piping also. You should be shutting off the next shut off valve going into house piping so that it doesn't run backwards.

Yes, there is a city meter/water shut off valve between the sidewalk and the street. The irrigation valve box is located just opposite the city meter. If you look close at the irrigation valve pic., you can see a ground wire. I traced this ground wire from the city meter to the house. This is how I came to the conclusion, this valve is tied into the main line. I sent a request to the builder to confirm. I haven't heard back yet. Initially, I only drained a few gallons after I shut it off. I'm going to try it again and let it run a lot longer to see if that works.

 

[Diehard]

Okay. I hope you understood what I was saying about the water running back from your house when you shut off that valve and draw water from that spigot. If you have a shut off valve between that hose bib and your house you should shut it.
For example, you could be draining your entire house piping, including possibly your water heater. Depending what arrangement you have for piping and equipment.

Can you see one or both of those 2 lines from the other side of the wall?

I agree in that an irrigation valve for you would not be located as you described. Since your irrigation system is obviously coming from that Irrigation Pressure Vacuum Breaker at the house.