If acid-rich water runs into a natural stream, pond, or lake, significant pollution and ecological damage may occur. The water can then become toxic to the plants and animals of that aquatic ecosystem. An acid is a substance that produces one or more hydrogen ions in water. Using an acid indicator can identify the presence of acids.
Litmus paper is used the most.
Blue litmus paper will turn a pinkish-red color if dipped into an acid. Red litmus paper will remain red in the presence of an acid. Litmus paper cannot tell the pH number of the acid. The concept of pH was first proposed by the Danish scientist S.P.L. Sorenson in 1909 to measure the acidity of water in brewing beer. The pH scale ranges from 0-14.