# Locating tap-in location



## Hoosier (Jun 12, 2018)

I plan to reconfigure my irrigation system, which was installed when the house was built 20 years ago. Hoping to use the existing "guts" of the system, and just update the sprinkler head locations, maybe split some zones up into multiple zones, etc. With the exception of the first 2 zones, all of the valves are in one box, so my plan is to add valves to that box if need be, and then re-run the pipe from each of those valves to where I need it to be. It's probably safe to say that the company that installed the system didn't put much time into calculating flow rate, pressure loss, etc., just based on the fact that the sprinkler head locations aren't even close to optimal for even/full coverage.

So, I have been reading and re-reading irrigationtutorials.com for the past week, and am designing as if there wasn't already a system, then seeing if I can make that work with the current setup without having to move valve locations or add boxes. I may design the system and then hire out the install, but even if I go that route, having them run the pvc from the current valves is probably quite a bit cheaper than moving valves or adding new valves/boxes in different locations.

I'm not far into the tutorials, but have mapped the yard and am at the stage of filling out the design data form (https://www.irrigationtutorials.com/data.htm).

I'm trying to determine my Available GPM, and to do that, I need to figure out where the current system is tapped into.

Here is a picture of the supply pipe (black PE) going into the house:

I think that the branch off of that is going to the hose bibs, if that's relevant. The supply pipe goes into the house about 4.5 feet below grade, so it's not practical to dig to that and follow it towards the water meter to see if the system taps in before it enters the house.

Outside, about 6 feet from where the supply line enters the house, there is an RPZ valve:


If the system is tapped into the hose bib pipe, I need to use the 3/4" specs (11 GPM), but if it's tapped into the supply line before it enters the house, I need to use the 1" specs (18 GPM).

Any guidance or ideas on how to determine this would be much appreciated.

Also a side note: I measured the circumference of the PE supply pipe at 90mm. Based on the guide on the website (2.96-3.33″ (75-85mm) = 3/4″ pipe OR 3.74-4.24″ (95-108mm) = 1″ pipe), I'm right in the middle of the two. I measured 3 times with a measuring tape to make sure I was correct. If the system is tapped into this supply line, and they for some reason used an odd sized pipe (for the US at least), am I safe to split the difference between the two (11 GPM vs 18 GPM) for my Available GPM, or should I use the lower of the two?


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## g-man (Jun 15, 2017)

Very easy to see if they tap before that supply point. Go trigger the irrigation to run. Make sure there is a sprinkler going and then close the ball valve in the blue PEX pipe there. If the system keeps the sprinklers going, then they tap before the house supply point.

As a side note, whoever did that PEX addition was not helping you. The house is on a 3/4 copper, but that's a 3/4 PEX pipe/valve. A 3/4PEX internal diameter is close to 1/2 copper. It is restricting your flow for no good reason.


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## Hoosier (Jun 12, 2018)

Thanks! Definitely a simple/logical solution. My brain must have been moving a little slower today.

Interesting to know about the plumbing. Had that put on only about a year ago due to the original shutoff going bad. Guess it might be time to find a new plumber - I would think matching the inside diameter should have been common knowledge for a professional.

Though in this case, any reduction in pressure probably isn't a terrible thing, albeit at the expense of that pipe and fittings... I just measured the pressure on a hose bib at 95 PSI, and the water company said earlier today that it was 85, so sounds like I need to look into dropping that in some way.


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