The water supply lines under my house and an attached apartment are poly butyl which I understand are no longer made. A plumber that was doing some other work, recommended that they be replaced with what I think he call "tek" plastic water supply lines. How big a job would this be, and is it something I could tackle myself? I hate sweat soldering copper pipe, and would like doing it even less while lying on my back in the crawl space under the house. How is the plastic attached to the existing copper lines, and would that have to be soldered? I'm guessing that all the plastic connections would be cemented together.