1 - 3 indicates a very acidic substance
4 - 6 indicates an acidic substance
7 indicates neutral
8 - 11 indicates alkalinity
12 - 14 indicates a very high level of alkalinity

Make sure your water is safe before using: Litmus paper is invaluable for testing the acid and alkaline levels in all kinds of applications from spas, ponds and aquariums to conducting scientific experiments.