Greywater Reuse Systems

Why Reuse Greywater?

• Greywater makes up 60 percent of the average household̵7;s wastewater. In areas of the country where water is a limited resource, conserving water is an important consideration. The ability to reuse wastewater when clean water isn̵7;t necessary can mean financial savings for the individual and environmental savings to overtaxed ground and surface water supplies. The nutrients carried in greywater may also act as fertilizer if it is used to water plants.

Uses for Greywater

• Greywater is most frequently used as a source of irrigation water for outdoor plants. It can be applied to lawns and ornamental plants and can be used in the garden so long as the greywater never contacts the edible portion of the plant -- a difficult proposition. Greywater can also be used to flush toilets, potentially saving 30 percent of the household water budget. Greywater that has been highly processed can even be used to wash your car, although the level of treatment required to make greywater that clean uses a lot of energy and resources.

Types of Greywater Reuse Systems

• The simplest, and often illegal, greywater reuse system is to use the water directly on plants. Most systems use filtration to remove particles and chemical or biological treatments to prevent pathogenic bacterial growth and clean the water. Chlorine or bromine is commonly used with the chemical treatments. Biological treatments utilize beneficial bacteria and aeration to consume organic matter. These systems need a storage tank to collect the accumulated greywater. Gravity or a pump can be used to move the greywater, depending on the design of the system. Many greywater reuse systems are designed for single family homes, but there are larger systems used by commercial buildings, or even municipalities.

Risks and Legalities of Greywater Reuse

• Greywater is only clean in relation to blackwater. If not treated properly, it can harbor and grow bacteria that are harmful to humans, causing many zoning boards and municipalities to ban greywater reuse systems entirely. Cleaner water requires more complex systems that increase both the hassle and cost of greywater reuse systems. The cost of the systems can outweigh the financial benefits of a reduced water bill. You will need to keep your greywater plumbing entirely separate from your blackwater and potable water plumbing. Finally, oils and particles in greywater can easily clog traditional irrigation systems and requiring a specially engineered system.