If you dont remember physical science class in school, then look up Litmus paper from red cabbage. It is an easy as hell recipe: Just boil a head of cabbage and soak coffee filters in your liquid after it cools, cut and keep for hundreds of ph papers to use.
You see, boiled cabbage maked neutral ph paper. Just get a color chart off of the net and work from there. Blue is basic, red is acidic. Pretty damn simple if you ask me.