[PSUscaper]

From the type of questions you are asking, I have to ask if you really think you should be attempting this job. It sounds like you have a lot of questions that are common knowledge to a irrigation guy, so I wonder what makes you think you are one when you can't answer any of them.

Digging holes for pipes is easy. Just like buying bricks and laying them on the ground is. A lot of people think the second, and there are a LOT of screwed up brick jobs out there.

I just think you should really think twice about getting involved in this one. Maybe for you own house, but still, I would seek a professional irrigation contractor. Get a price from someone, tack on 10% and walk away with a profit and most of all, no headaches.

And what do you mean by 'tap the mainline'? I hope you don't plan on digging up the well line in the yard and tapping directly into that.

As for backflows, they have nothing to do with making it easy to blow out the system. They are there to protect the main water supply from being contaminated.

I really, really would urge you to think twice about this one.