There are several possibilities for the cloudiness. Some leftover debris in the gravel could be causing a bacterial bloom. Or could there be some powder in the gravel?
Some tap water sources just "cloud up" when you first set up a tank. I used to live in an area where I had this problem. I never did figure out what caused it, but every new tank I set up would get cloudy. Eventually the cloudiness would clear up and the water would stay clear from then on.
You can try "starting over" as Kaysie suggests. It wouldn't hurt. But if the cloudiness happens the second time, the only thing you can do is run the tank empty for a few weeks until the cloudiness goes away. Using some water from your old tank may help. Before you transfer the newt, you might want to move some if the gravel, or ornaments, or filter media to the new tank to seed the biofilter.