HooKooDooKu,
I checked the front and back and both faucets bibs reads 50psi. Right now I am using a 3/4" pvc coming off the faucet header line and then using 1/2" pvc lateral line to sprinkler head. My main line close to the meter is using a 1/2" copper pipe with 50psi that is 6.5 gpm.
You said 6gpm going through a 1/2" copper pipe reaches the danger zone. Does this mean I could have a pipe inside my house burst by setting up this type of system using the ouside faucet? If that is the case it would be better if I did use the main water line. thanks for your help
By "danger zone", you run the risk of water hammer which can cause damage inside the house. I doubt a properly soildered 1/2" copper pipe is going to burst, but some weak point, perhaps a connector or the hose that feeds things like the dish washer, the toilets, or washing machines could break. Basically, most indoor plumbing is only speced for 50psi. When you get water hammer (loud bang caused when high velocity water suddenly stops moving because a valve quickly closed), that causes a water pressure spike in the plumbing. That pressure spike is what, over time, could lead to the failure of some part of the plumbing system. So if you're mainline from the meter to the house really is 1/2" (usually from what I've seen and heard, that's usually 3/4" copper or 1" PVC or similar), then you want to tie into that pipe as early as possible to minimize the possibility of water hammer and to minimize pressure losses. When it comes to water hammer, where you tie into the mainline doesn't matter. If you have water hammer, the pressure spike will go through the entire house. But by tying in as close to the meter as possible and immediately upsizing to 1"PVC, you'll minimize the possibility of water hammer.
If you read over the online guide
www.irrigationtutorials.com, you will see that the expert that put this totorial together basically says that 1/2" pipes have no place in irrigation. Basically, the pressure losses are just too great. So I would agree with hi.todd and suggest that you use 3/4" Sch40 PVC at a minimum, and because it allows for even less pressure losses without much of a price increase, that you instead use 1" PCV. Basically, so much 1" and 3/4" PVC is used, that the prices between the two are relatively small for the common components. You don't see a major price jump until you start getting into the 1-1/4" and above sizes. When it comes to irrigation, for many reasons, bigger is always better (in terms of sizing pipes). So if you haven't purchased the materials, I'd suggest 1" Sch40 PVC for your main line AND latterals. For one thing, it will make purchasing parts and spare parts easier since everything will be 1". For the irrigation system I put in my yard, the only place I used anything smaller than 1" was the 3/4" pipes I used for drip irrigation latterals. Otherwise, I used 1" right to each sprinkler head.