Greywater is gently used water from your bathroom sinks, showers, tubs, and washing machines. It is not water that has come into contact with feces, either from the toilet or from washing diapers.
Greywater may contain traces of dirt, food, grease, hair, and certain household cleaning products. While greywater may look “dirty,” it is a safe and even beneficial source of water for a non-portable or non-drinking purpose. Keep in mind that if greywater is released into rivers, lakes, or estuaries, its nutrients become pollutants, but to plants, they are valuable fertilizer. Aside from the obvious benefits of saving water (and money on your water bill), reusing your greywater keeps it out of the sewer or septic system, thereby reducing the chance that it will pollute local water bodies. Reusing greywater for both toilet flushing using dual plumbing, and irrigation reconnects urban residents to the natural water cycle.
The easiest way to use greywater is to pipe it directly outside and use it to water ornamental plants or fruit trees. Greywater can also be used to irrigate vegetable plants as long as it doesn’t touch edible parts of the plants. In any greywater system, it is essential to use “plant friendly” products, those without salts, boron, or chlorine bleach. The build-up of salts and boron in the soil can damage plants. While you’re at it, watch out for your own health: “natural” body products often
contain substances toxic to humans.
We promote greywater reuse as a way to increase the productivity of sustainable backyard ecosystems that produce food, clean water, and shelter wildlife. Such systems recover valuable “waste” products–greywater, household compost, and humanure–and reconnect their human inhabitants to ecological cycles. By modeling “appropriate technologies” for food production, water, and sanitation in the industrialized world, we hope to replace the cultural misconception of “wastewater” with the possibility of a life-generating water culture.
Basic Greywater Guidelines
Greywater is different from fresh water and requires different guidelines for it to be reused. Don’t store greywater (more than 24 hours). If you store greywater the nutrients in it will start to break down, creating bad odors.
Minimize contact with greywater. Greywater could potentially contain a pathogen if an infected person’s feces got into the water, so your system should be designed for the water to soak into the ground and not be available for people or animals to drink. Keep your system as simple as possible. Simple systems last longer, require less maintenance, require less energy and cost less money. Install a 3-way valve for easy switching between the greywater system and the sewer/septic.