I used the plastic drain pipe and a couple of "T's" to solve my water line dilema as well. After running the poly line from the house and putting the last 25'-20' or so in drain line, I used a 1' poly to 3/4" cpvc threaded adapter into a cpvc 3/4" "T" to bring a 3/4" cpvc water supply line up thru a drain pipe "T" and riser. The 3/4" cpvc water supply riser will terminate aboveground in a "T", with one end feeding the wash basin in the garage and the other an outside hose bib. The poly water line extends past the water riser "T" into a cpvc ball valve using another 1" poly to 3/4" threaded adapter.