What Is Wastewater?

When water becomes wastewater:

The potable water becomes wastewater after it gets contaminated with natural or synthetic microbiological compounds that arises 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 have 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 nonresidential sources.

Residential wastewater:

Although the word sewage usually brings toilets to mind, it is actually used to describe all types of wastewater generated from every room in a house. In the U.S, sewage varies regionally and from home to home. They are based on factors such as the number and type of water-using fixtures and appliances, the number of occupants, their ages, and even their habits, such as the types of food they eat. However, when compared to the variety of wastewater flows generated by different nonresidential sources, household wastewater shares many similar characteristics overall. 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 that require treatment.

Nonresidential wastewater:

Nonresidential wastewater in small communities is generated by diverse sources like offices, businesses, Super markets, restaurants, schools, hospitals, farms, manufacturers, and other commercial, industrial, and institutional entities. Storm-water is a nonresidential source and carries trash and other pollutants from streets, as well as pesticides and fertilizers from yards and fields.

Because of the different nonresidential wastewater characteristics, communities need to assess each source individually or compare similar types of nonresidential sources to ensure that adequate treatment is provided. For example, public restrooms may generate wastewater with some characteristics similar to sewage, but usually at higher volumes and at different peak hours. The volume and pattern of wastewater flows from rental properties, hotels, and recreation areas often vary seasonally as well.

Laundries differ from many other nonresidential sources because they produce high volumes of wastewater containing lint fibers. Restaurants typically generate a lot of oil and grease. It may be necessary to provide pretreatment of oil and grease from restaurants or to collect it prior to treatment. For example, by adding grease traps to septic tanks.

Wastewater from some nonresidential sources also may require additional treatment. For example, storm-water should be collected separately to prevent the flooding of treatment plants during wet weather. Screens often remove trash and other large solids from storm sewers. In addition, many industries produce wastewater high in chemical and biological pollutants that, can overburden onsite and community systems. Dairy farms and breweries are good examples. Communities may require these types of nonresidential sources to provide their own treatment or preliminary treatment to protect community systems and public health.

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