About Greywater Reuse


Greywater is gently used water from your showers, tubs, bathroom sinks, and washing machines. It is not water which has come into contact with feces such as water from the toilet or from the washing diapers.

Greywater may contain traces of food, dirt, hair, grease, and certain household cleaning products. Although greywater may look dirty, it is a safe and beneficial source of irrigation water. Remember that if greywater is released into lakes, estuaries, or rivers, it becomes pollutants, but to plants, it is valuable fertilizer. Besides the obvious benefits of saving water and even money on your water bill, reusing greywater keeps it out of the septic or sewer system, thereby reducing the chance it pollutes the local water bodies. Reusing greywater for irrigation reconnects our backyard gardens and urban residents to the natural water cycle.

The most simple way to reuse greywater is to directly pipe it outside and use it to water fruit trees or ornamental plants. In addition, greywater can be used to irrigate vegetable plants because it doesn’t touch the edible parts of the plants. In each greywater system, it is necessary to use “plant-friendly” products, those without much boron, chlorine bleach, or salt. The build-up of boron and salt in the soil can damage plants.

Basic Greywater Guidelines

Greywater is different from fresh water so it requires the different guidelines to be reused.

  1. Don’t store greywater for more than 24 hours. If you store greywater, its nutrients will break down and create bad odors.
  2. Minimize contact with greywater. Greywater might contain a pathogen if the feces of an infected person got into the water, therefore, your system should be designed for the greywater to soak into the ground and not be available for either people or animals to drink.
  3. Keep your greywater system as simple as possible, avoid pumps and filters which need upkeep.
  4. Install a 3-way valve to easily switch between the system and the septic/sewer.
  5. Match the amount of greywater that your plants will receive from the system with their irrigation needs.