Water quality is the physical, chemical and biological characteristics of water. It is a measure of the condition of water relative to the requirements of the application. It is most frequently used by reference to a set of standards against which compliance can be assessed. The most common standards used to assess water quality relate to drinking water, safety of human contact and for the health of ecosystems.
Water quality is a very complex subject, in part because water is a complex medium intrinsically tied to the ecology of the Earth. Industrial pollution is a major cause of water pollution, as well as runoff from agricultural areas, urban stormwater runoff and discharge of treated and untreated sewage (especially in developing countries).
The complexity of water quality as a subject is reflected in the many types of measurements of water quality indicators. The list below represents some of the simple measurements that can be made on-site in direct contact with the water source in question:
- Total Dissolved Solids (TDS)
- Oxidation Reduction Potential (ORP)
- Dissolved oxygen
More complex measurements that must be made in a lab setting require a water sample to be collected, preserved, and analyzed at another location. Making these complex measurements can be expensive. Because direct measurements of water quality can be expensive, ongoing monitoring programs are typically conducted by government agencies. However, there are local volunteer programs and resources available for some general assessment. Tools available to the general public can be found here.