Why do we need to analyze water?

• If water is badly polluted-- like raw sewage--- it might be obvious from its appearance or odor
• It might be colored or turbid (cloudy), or have solids, oil or foam floating on it.
• It might have a rotten odor, or smell like industrial chemicals.
• A lot of dead fish floating on the surface of a lake would be a clear sign that something was wrong.
• But many harmful-- and beneficial-- materials in water are invisible and odorless. In order to go beyond the obvious, to determine what materials are in the water, and how much, we need to be able to conduct chemical or microbiological analyses.

But many harmful-- and beneficial-- materials in water are invisible and odorless. In order to go beyond the obvious, to determine what materials are in the water, and how much, we need to be able to conduct chemical or microbiological analyses.

Analysis of a natural body of water will tell us how clean or polluted it is. If there is damage to wildlife, the measurements will help pinpoint the cause-- and the source. In a wastewater treatment plant, analyses are necessary for monitoring the effectiveness of the treatment processes. In the United States, the Clean Water Act requires wastewater dischargers to have permits. These permits set limits on the amounts of specific pollutants which can be discharged, as well as a schedule for monitoring and reporting the results. Usually, the reports must be filed monthly, while the measurement frequency for a particular parameter (measurable property) can run anywhere from "continuously" to just once a year. Only standard analytical procedures specified in the "Code of Federal Regulations" may be used, so that the government agencies can feel reasonably confident that results from different laboratories are comparable.

Similar considerations apply to drinking water. The purity of the water we drink is of more concern to the average person than the quality of the wastewater discharged by the sewage plant. But we should not forget that in many places, especially along a river, one town's wastewater discharge may be part of the next town's water supply...