But if it has some sort of valve then it's not a true gravity sys. I shouldve better explained the system I'm wondering about uses no pumps or electricity of any kindput a resivor up higher then all of your pots hook drip lines have on and off value on rez, when they need water fill the res with water and turn the value on only use as much as u need, set up drain hose and use for mothers, use fresh water every time and u wont have no stale or infected water.