Water Chemistry  pH  A measure of the acidic or basic the water is  On a scale of 1-14  1 is very acidic and 14 is very basic  7 is neutral Freshwater 3-10 Freshwater 3-10 Rainwater 5-6 Rainwater 5-6 Streams and lakes 6.5-8.5 Streams and lakes 6.5-8.5  Limestone under the water causes the pH to increase  (or become more basic)