Wastewater - Contamination Sources

What is wastewater?

The potable water becomes wastewater after it gets contaminated with natural or synthetic microbiological compounds that arise out of human activities, commercial and industrial sources. They may be accompanied with surface water, ground water and storm water. Wastewater is sewage, storm-water and water that has been used for various purposes around the community. Unless properly treated, wastewater can harm public health and the environment.

Most communities generate wastewater from both residential and non-residential sources.

Residential Wastewater or Household Wastewater

Residential wastewater is a combination of excreta, flush water and all types of wastewater generated from every room in a house. It is more commonly known as sewage and is much diluted. There are two types of domestic sewage: black-water or wastewater from toilets, and gray water, which is wastewater from all sources except toilets. Black-water and gray-water have different characteristics, but both contain pollutants and disease causing agents. In the U.S, sewage varies regionally and from home to home. These are based on factors such as the number and type of water-using fixtures and appliances used at homes and even their habits, such as the types of food they eat.

Non-Residential Wastewater or Industrial Wastewater

This could be places such as industrial complexes, factories, offices, restaurants, farms and hospitals.  Because of the different non-residential wastewater characteristics, communities need to assess each source individually to ensure that adequate treatment is provided. For example, laundries differ from many other industrial sources because they produce high volumes of wastewater containing lint fibers. Restaurants typically generate a lot of oil and grease. In addition, many industries produce wastewater high in chemical and biological pollutants that, can overburden onsite and community wastewater treatment systems.

Storm-water is a nonresidential source and carries trash and other pollutants from streets, as well as pesticides and fertilizers from yards and fields. Communities may require these types of nonresidential sources to provide preliminary treatment to protect community systems and public health.