Water Quality
Water Quality is a function of its physical, chemical, and biological properties. High quality water is suitable for human drinking water, industrial and agricultural use and will support the life cycles of fish and wildlife. Poor water quality may not be suitable for some uses, but may still be good for other uses. For instance, water that does not meet federal drinking water standards may still be good enough for irrigation or industrial use.

Water quality protection in the United States is under the authority of the U.S. Environmental Protection Agency (EPA) and the individual state in which a water body resides. Water quality can be impaired by discharges from point sources like sewage treatment plants and industrial operations. It can also be impacted by runoff from nonpoint sources such as urban areas and from agricultural and non-agricultural operations. Federal and state laws and regulations require that point sources obtain a discharge permit that restricts the level of discharge so that water quality is not impaired to the point that it will not support uses such as drinking water and other important uses. Nonpoint sources are expected to manage their impacts through development and implementation of water quality management plans.

No single water quality characteristic can be used to verify that the water is suitable for a particular use. For instance, water in a well may be free of bacteria, but may still contain nitrate-nitrogen in excess of federal standards. One cannot see, smell or taste elevated levels of nitrate-nitrogen so the only way to know is to test it regularly.


The complexity of water quality as a subject is reflected in the many types of measurements of water and Wastewater quality indicators. These measurements include (from simple and basic to more complex).

  • Electro Conductivity
  • Dissolved Oxygen
  • pH (amount of Acidity & Alkalinity)
  • Taste and Color
  • Turbidity
  • Total suspended solids (TSS)
  • Dissolved Metals and Salts
  • Chemical oxygen demand (COD)
  • Biochemical Oxygen Demand (BOD)
  • Microorganisms
  • Nutrients, such as nitrogen and phosphorus
  • Dissolved Metals and Metalloids
  • Dissolved Organics (CDOM) & (DOC)
  • Temperature
  • Pesticides
  • Heavy Metals
  • Pharmaceuticals
  • Hormone Analogs
Some of the simple measurements listed above can be made on-site (temperature, pH, dissolved oxygen, conductivity), in direct contact with the water source in question. 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 typical conducted by government agencies. Individuals interested in monitoring water quality who cannot afford or manage lab scale analysis can also use biological indicators to get a general reading of water quality. Biological monitoring metrics have been developed in many places, and one widely used measure is the presence and abundance of members of the insect orders Ephemeroptera, Plecoptera, and Trichoptera (EPT). EPT indexes will naturally vary from region to region, but generally, within a region, the greater the number of taxa from these orders, the better the water quality.


Homepage   About GeoTech   About Water   About Rock   Core Info

If you have any problems or comments regarding this site please email our Webmaster