Dilution itself won't make you come up positive. When you run a home dilution run you don't even need to worry about color, gravity etc. because it doesn't test for that (unless you want to try it all the way through and make sure you will get it right). All your doing is checking if when you raise the ratio of water to metabolites, will it put you under the 50ng/ml limit. So run N2's guide using only the water part. 2 8oz cups, followed by a cup every 15 minutes. Use your pee only once it starts coming out clear (you'll avoid the clear pee the actual day of the test) usually about your 4th or 5th time peeing.