I am getting ready to start the installation of copper pipe in my hot water line rerouting. In some cases, it will be easier to solder the fitting on to one pipe and then on to another. Are there any tips for this so I don't "un-solder" the first connection?

Hi! A new guy here. I recently bought my new house and moved in with my family. I’ve been doing a lot of projects around the house but they were mostly concentrated on air sealing/insulation/winterizing. I have another project in my queue that I will get to before the spring and I wanted to ask the community for an opinion for it. I have to water lines coming to my house – main and sprinkler lines. They billed differently and because main line water ends up in the municipal sewer it’s twice as expensive and sprinkler water. I have 3 outside faucets that for some reason are connected back to main line instead of the sprinkler. It gets expensive to fill up my pool in the spring using one of those facets since I’m charged twice for it. Also watering the lawn or doing anything outside with that water also gets charged twice even though not a drop of the water from those faucets ends up in the sewer. So I want to correct this. On the first picture you can see two line splitting into two meters and then to separate pipes. The top meter is on sprinkler line. At the top of the main line there is branch that goes to outside faucets. You can see it on the very top of the first picture and on the second picture. I plan on disconnecting the elbow on the faucets branch (A) and installing a Tee on the sprinkler line (B), adding a gate valve and drain valve and connecting it back to the faucets line. [IMG]http://lh4.ggpht.com/_rVOlNnuoUN0/TQpEVAQhlkI/AAAAAAAAB0M/wzxSEv5_OCE/s640/IMGP1080.JPG[/IMG] [IMG]http://lh4.ggpht.com/_rVOlNnuoUN0/TQpEVffcinI/AAAAAAAAB0Q/iyBsvAHnXpE/s512/IMGP1082.JPG[/IMG] Here are my two questions/concerns: 1. Why was it done like that in first place? Will I violate any codes with what I want to do? I don’t really see how, if anything I would be putting sprinkler-grade water (the one that goes outside) to sprinkler line. 2. The sprinkler line section that I can cut into and installed a Tee is somewhat short. I’m afraid that if I cut into it, it will not have enough wiggle room to put a Tee fitting since I might not be able to push two part of the cut pipe apart enough. Is there a solution for this kind of a problem? All I can think of is – cut as needed and if it doesn’t work, cut a bigger section of the pipe off and then install some flexible pipe (PEX?) that will give me enough room to connect it back together? The area is somewhat cramp and there is styrofoam right behind the pipe, so I might end up doing either compression fittings or push-in fittings like SharkBite so it would work with Pex pipe. Am I missing some simpler solution here? Something like saddle valve would be ideal, but it won’t provide enough preassure/volume for this application. Thanks for reading this long post and I hope someone can help me out with some sound advice on this. Stan.