What is Greywater Recycling?

Greywater recycling involves the reuse of washwater such as water from sinks and washing machines. There are a variety of ways in which a greywater recycling system can be set up, creating an assortment of options ranging from a source of water for irrigation to potentially potable water for drinking and cooking. There are several advantages to greywater recycling which make it popular in areas where the supply of water is limited, and in regions where people are concerned about the impact of their water usage on the environment.

The term “greywater” is used to describe wastewater derived from washing processes, excluding wastewater from the toilet, which is known as blackwater. Some people also bundle wastewater from kitchen sinks in with blackwater, arguing that it has a higher risk of containing harmful pathogens. Even greywater can sometimes host an assortment of bacterial visitors, but at much lower concentrations than blackwater, making it perfectly safe for plants and toilet flushing.

The setup of a greywater recycling system is fairly straightforward. It involves routing water from sinks, showers, and washing machines to a separate holding tank, rather than allowing it to go into the sewer system. Depending on how the greywater is being used, it may be used directly for irrigation and toilet flushing, ideally after being passed through a sand or charcoal filter to remove big particles, or it can be treated in a variety of ways to make it clean enough to drink. Obviously, the first option is less expensive and time consuming to install.

There are several reasons to install a greywater recycling system. The immediate obvious advantage is a dramatic reduction in water use, especially if greywater is used to flush the toilet. This can cut down on water bills dramatically. In addition, it reduces the risk of sewage spills and contamination; normally, black and greywater are processed together, essentially contaminating the greywater with the blackwater and creating a huge volume of water which must be carefully handled and treated so that it does not pollute waterways, the air, or the soil. By taking greywater out of the mix, people can reduce the strain on septic and sewage systems.

When greywater is used for irrigation, caution is advised. Most greywater is pH neutral or alkaline, which can be good or bad for plants, depending on the plants. It is also not a good idea to use harsh soaps or heavy chemicals in greywater intended for irrigation, as these can damage plants. It pays to research the plants in the garden carefully before watering with greywater, and for homeowners putting in new gardens, it can be a good idea to plant a greywater friendly garden.

Before running out and installing a greywater recycling system, there is an important issue to keep in mind. In some regions, greywater recycling is explicitly banned, and in other instances, homeowners may be required to go through an extensive permitting process. In the interest of keeping a home legal and up to code, it is important to research building regulations for information on greywater, as otherwise a greywater recycling system could become a liability, especially if the home was ever sold.