Greywater, or sullage, is wastewater generated from domestic activities such as laundry, dishwashing, and bathing, which can be recycled on-site for uses such as landscape irrigation and constructed wetlands. Greywater differs from water from the toilets which is designated sewage or blackwater to indicate it contains human waste.

Greywater - what it is, how to treat it, how to use it

Greywater Action

How Gray Water Reclamation Works

What is gray water, and can it solve the global water crisis?

Greywater Recycling

Greywater Purification Systems

System selection

Greywater system selection chart

Greywater site assessment/system checklist

Building a biological DIY greywater system (with no reedbeds)

CELEBRATE YOUR WASTE: Grey water system

Greywater Irrigation Systems

Constructed Wetland

A constructed wetland or wetpark is an artificial wetland created as a new or restored habitat for native and migratory wildlife, for anthropogenic discharge such as wastewater, stormwater runoff, or sewage treatment, for land reclamation after mining, refineries, or other ecological disturbances such as required mitigation for natural areas lost to a development.
Natural wetlands act as a biofilter, removing sediments and pollutants such as heavy metals from the water, and constructed wetlands can be designed to emulate these features.

Wetland information

DIY Greywater Pond System

Greywater Pond Building

Wild life in greywater ponds

Lava Filter

A lava filter is a biological filter that uses lavastone pebbles as support material on which microorganisms can grow in a thin biofilm. This community of microorganisms, known as the periphyton break down the odor components in the air, such as hydrogen sulfide. The biodegradation processes that occurs is provided by the bacteria themselves. In order for this to work, sufficient oxygen as well as water and nutrients (for cell growth) is to be supplied.

Woodchip biofilter for kitchen sink wetlands

Evaporation Ponds

Living Machines


Blackwater & Nightsoil


Night soil

Feedback on Night Soil: Composting Human Waste

Using Human Manure ("nightsoil") in the Tai Lake Region of China

Night Soil & Gardening

Utilisation of composted night soil in fish production

Use of night soil in agriculture and fish farming

Safe use of treated night soil 

Reuse of excreta

Traditional night-soil composting continues to bring benefits




Human and Animal Pathogens in Manure

The Control of Pathogens from Human Waste and Their Aquatic Vectors

Pathogens and Composting Toilet Systems

Stanley Falkow: Human-Pathogen Interaction

Ninety percent of the cells humans carry are microbes. Only a few of the bacteria we encounter are pathogenic and can cause disease. Pathogens possess the inherent ability to cross anatomic barriers or breach other host defenses that limit the microbes that make up our normal flora. A significant part of human evolution has gone into developing ways to thwart microbial intrusion. In turn, microbes have come up with clever ways to avoid and circumvent host defenses but human — microbe interactions is still a "Work in Progress." When we study pathogens we learn as much about ourselves as we do about them.

Helicobacter pylori lives in the human stomach. It causes gastritis, ulcer disease and even gastric cancer. Some H. pylori can inject a protein, CagA, into gastric epithelial cells. CagA interacts with the tight junctions that bind cells together and with signaling molecules affecting motility and proliferation. CagA is associated with ulcer disease and cancer but we don't understand how it works to favor malignancy. Not long ago in history most humans carried H. pylori ; the incidence of carriage and gastric cancer is dropping but there is evidence that this microbe also had a protective effect on human health.

See also

Compost Toilets
(can be used to avoid creating black water)

(info on how to use the recycled water to create fertility)

(how to use the vegetation grown in greywater or blackwater systems, or night soil, to make biogas, while rendering them pathogen-free)