i have monitored the amount of water Roxy gets since we got her at 7 weeks. We give her about a half cup at a time, after she goes pee, she can have more. That way it's easier for us to tell when she has to pee, rather than filling her water bowl to the top and having her casually drink. (I actually tried that the other night and she was peeing everywhere in the house!)
Signs they have to go out: sudden disintrest in an activity, immediately after they wake up (even if they're only asleep for 5 minutes).
Don't give them the opportunity to go in the house. Bring them outside every 10 minutes if you have to. That's what we did in the beginning because we just got sick of cleaning up puppy puddles!! Then when they do pee outside throw a party!!! You cannot praise them enough!!
When Roxy was a tiny pup and we'd take her outside to pee. When she finally would go we'd say, Calmly to her, "good pee, roxy." Then when she was done we'd freak out, loving on her, praising her, etc.
Be consistent, but the best thing i can say, is don't give them the opportunity to go in the house. Take them out every 5-10 minutes, eventually they'll get it. They'll still have accidents, but they won't be as frequent.