What is pH?

The pH scale is used to measure whether a substance is acidic or basic. Pure water has a pH of 7, which is considered neutral. Substances having a pH of 1 (such as battery acid) are extremely acidic, while substances having a pH of 13 (such as lye) are extremely basic or alkaline.

FYI: The pH scale is logarithmic. That means a liquid with a pH = 3 is ten times as acidic as a liquid with a pH = 4.

The pH of some common liquids:

-- Water & Health Activities Quick Links -- Clark Lantz/ Arsenic Chlorine vs. Diseases pH Basics pH Basics Q&A Sodium Total Dissolved Solids Water Survery Partners Tucson Water Collaboration

Are there health concerns related to pH?

Drinking water (from the tap or bought at the store) is typically near the neutral pH value. Tucson's water is slightly alkaline averaging between 7.5 and 8.2.

Exposure to extreme pH values (above 10 or below 4) can lead to health effects including irritation of the eyes, skin, and mucous membranes. In addition, high pH has been associated with swollen hair fibers and exacerbation of skin disorders.

Other pH issues:

The pH is important for water treatment processes, including disinfection with chlorine. The pH must be controlled to prevent the corrosion of water mains and pipes in household systems, which can lead to a poor taste, odor, and appearance.

Southwest Environmental Health Sciences Center
University of Arizona College of Pharmacy, Room 244
PO Box 210207, Tucson, AZ, USA  85721-0207
swehsc-info@pharmacy.arizona.edu
520-626-5594
520-626-6944(FAX)