pH

Background Information

pH measures the relative acidity of the water. A pH level of 7.0 is considered neutral. Pure water has a pH of 7.0. Water with a pH level less than 7.0 is considered to be acidic. The lower the pH, the more acidic the water. Water with a pH greater than 7.0 is considered to be basic or alkaline. The greater the pH, the greater its alkalinity. In the US, the pH of natural water is usually between 6.5 and 8.5. Industries and motor vehicles emit nitrogen oxides and sulfur oxides into the environment. When these emissions combine with water vapor in the atmosphere, they form acids. The presence of these acids causes rain to be acidic. Acid rain damages trees, crops, and buildings. It can make lakes and rivers so acidic that fish cannot survive.

Test Procedure

To perform the pH test, use a pH test kit from LaMotte (or other supplier). Follow the instructions provided with the kit. pH must be measured immediately at the test site because changes in temperature affect pH value. Try to take the water sample away from the bank and below the water surface. pH is recorded with a number value only. There are no units associated with it.

What to Expect

A pH reading between 6.5-7.5 is considered to be excellent; the water is neutral. A pH level between 6-6.4 or 7.6-8.0 is considered to be good. A pH level between 5.5-5.9 or 8.1-8.5 is considered to be fair. If the water's pH level is less than 5.5 it is very acidic and is at a level where fish and other organisms may find it impossible to survive. A pH level greater than 8.6 is considered to be very alkaline and this is not good either.

References