I'm a newbie too, but as far as what I read you really dont want to use straight tap water because of all the crap it contains, but they say mostly about the Cholrine in the water. This can be fixed by leaving the water out room temp for 24hrs. Personally I have one of those Brita water filters on my faucet so I use that and don't have any problems. The ventalation i'm not so sure about but I have my grow in a closet. I just leave the door open since I only have a few plants growing. The air circulating through my apartment takes care of that for me, plus I have central air/ heat. So it pushes the air around my plants pretty well. So take what I say with a grain of salt cause like I said I'm a noob too, but this is just from my experience with my grow. Hope it helps!!