Updated: May 16, 2022

Grey Water / Reclaimed Water

Greywater Reuse

Greywater is any household wastewater other than that used for toilet flushing. This water could be reused around the home (for purposes other than drinking water). An example of greywater use is landscape irrigation. Wastewater that comes in contact with human waste is referred to as blackwater. However, the definition of greywater varies according to state regulations. In many states greywater is defined as household wastewater from baths, showers, laundry washing, and lavatory sinks. However, greywater does not include wastewater from kitchen sinks, dishwashers, and toilets. Kitchen sink and dishwasher wastewater is often classified as blackwater because it may contain higher levels of organic materials (such as food waste) compared to greywater sources. The high organic content of these blackwater sources can lead to low oxygen content and greater microbial activity, and thus may require more stringent treatment. Additionally, if laundry water is used for diaper washing it is usually classified as blackwater rather than greywater since it has come in contact with human waste.

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Guidelines for use of Class IV Reclaimed Water: High Potential for Human Contact

Reclaimed water is wastewater from a municipal sewage treatment facility that has been treated to be suitable for beneficial use. Reclaimed water is categorized into four water quality Classes (I-IV) which govern their potential uses based on the level of treatment (or quality) attained. These guidelines apply only to use of Class IV reclaimed water generated from a centralized wastewater treatment works. Guidance on the use of Class I, II and III reclaimed water can be found in the Department’s Guidelines for Land Application/Reuse of Treated Municipal Wastewaters (MDE-WMA-001-04/10).

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