In order to understand what a chemical measurement means, one needs to have a basic understanding of the type of measuring units used, and what they mean. As mentioned above, most of our contaminants are measured using concentration units such as ppm and ppb. But what is a ppm, ppb, or ppt for that matter, in plain English?
As an example, let’s use an example of liquid chlorine added to our water in the treatment process at 1.0 ppm. This value refers to one part of chemical (in this case liquid chlorine) found in one million parts of our water. To realize how small a value this actually is and how difficult this contaminate is to trace in the environment, read the analogies listed below:
One part per million (ppm) equals:
One part per billion (ppb) equals:
One part per trillion (ppt) equals:
- 1 inch in 16 million miles (600+ times around the earth)