Agricultural and Biosystems Engineering
Testing water is the first step in tackling domestic water quality problems. Water test reports will confirm your suspicion of quality problems. With results in hand you can determine the extent of the problem and the best alternative to solve it. A water test gives a quantifiable level of a contaminant at the time the sample was taken. These values usually are reported in mg/L (milligrams per liter).
Derickson, Russ, "Drinking Water Standards- Health Advisories Levels" (2002). SDSU Extension Extra Archives. 24.