evidence: - Acidic water has a pH lower than 7. Strongly acidic substances can have a pH of 0. Battery acid falls into this category. [...] Acidic water with a pH of less than 6.5 is more likely to be contaminated with pollutants, making it unsafe to drink. It can also corrode (dissolve) metal pipes. [...] If your drinking water pH falls outside of the safe range, it’s time to act. Call your local drinking water company to alert them to your test findings.