Why Water Is Neutral

Pure water is neutral at pH 7 because a tiny fraction of water molecules constantly split into H+ and OH- ions in equal amounts.

Water quality depends heavily on pH. Acid rain (pH below 5.6) damages forests, kills fish, and dissolves stone buildings. Ocean water normally sits at pH 8.1, but rising CO2 levels are causing ocean acidification — the pH has already dropped by 0.1 units since industrialization.