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Dedicated supply line or tee off existing supply line

Posted by taylorjonl 5 (My Page) on
Wed, Sep 25, 13 at 21:11

I am trying to renovate a sprinkler system on an older house. The sprinkler that the previous owners installed wasn't very good, so I am redoing it.

My plans are to start with the front yard this year or early next year and depending on how it goes do the back and side yard the year after. I am trying to get at least the supply line put in this year, or at least the parts that will be in the front yard so I can plant next year and not have to disturb the plants.

I was planning on using a 1" PVC for all the supply lines to the various valve boxes in the front, back and side yard. I plan on using fertigation so I need to install a backflow preventer.

To start out I yanked out the old sprinklers in the front yard and dug out the junction point for the existing supply line. It is tee'd into the water going into the house. It appears to be either 1/2" or 3/4" iron piping, I attached a photo.

So I have a few questions:

1) Is it best to have a dedicated line from the water main for the sprinkler?
2) If the line from the main is 1/2" or 3/4" iron piping, does it make sense to have 1" PVC for the supply lines?
3) If a dedicated line is best, how much would you expect to pay to have it installed(the water main is 25' directly south in my parking strip and my front yard is yanked up and free of cables/obstructions).

Any help is appreciated.

Follow-Up Postings:

RE: Dedicated supply line or tee off existing supply line


1) Maybe, if you want the maximum pressure compared to taking water off your outside faucet which has its pressured reduced along with your house to about 45 psi. Usually the street pressure is somewhere between 55 to 70 psi. If the street pressure is too high then the pressure needs to lowered to about 60 psi with a pressure reducer. Lower pressure means more zones you will need to operate with your controller.

2) It is fine. It just means a higher velocity through the smaller pipe which causes more noise. If buried not a real problem. A larger pipe means less velocity and a larger maximum flow rate for a certain system pressure.

3) This question is confusing. Are you asking about installing a compression tee at your house mainline and then bring 1" pvc from there. Is that your mainline that feed your house at the bottom of the excavation. It looks small. Usually mainlines to houses are 5/8" up to 1". That line looks like a 1/2" main.

My suggestion is test your system pressure then lets discuss you answers again.

RE: Dedicated supply line or tee off existing supply line

Thank you for your input.

1) Lower pressure doesn't bother me, I am planning on running sub-surface drip everywhere, using Rain Bird XFS tubing with 18" spacing. The valves I bought have built in regulators for 30 PSI.

2) I think the flow rate should be pretty low, the max flow per drip zone is 5 GPM, the valve is a Rain Bird XCZ075PRF.

3) I was thinking of replacing the 30 year old water line from the main to my house. I attached another picture that show the distance, the water main is in the parking strip and the dirt pile is about where the hole I dug is that is where the water enter the house and where the sprinkler tees off of.

RE: Dedicated supply line or tee off existing supply line


What is the size of the existing water main from the street to the house? Where is the water meter and box located and do you have a valve main shut-off after the water meter and box?

RE: Dedicated supply line or tee off existing supply line

I am not sure of the size of the outlet from the water main, the main box got a bunch of dirt in it when the bushes that were planted on the parking strip were removed. I plan on cleaning it out tomorrow, today has been very wet and cold so trying to stay out of the yard.

I attached another image with a different angle, you can see the water main cover in the parking strip. The image is scaled, but basically the main is about half way on the parking strip, a straight show to the bottom left window on my house where the current supply line enters my house.

I will know more about whether I have a valve after I clean out the main box.

I have a plumber coming out on Monday to give me a quote, to run 1" PE pipe and to install the backflow preventer I just bought. I have done a bit more reading and realize a dedicated line is not needed but a bigger line may be useful and the key to me is a newer line that won't have issues in 5 years after I have all the plants in and established.

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