Grey Water
Introduction
Domestic waste water is made up of grey water and black water; grey water is the waste water from bathrooms, kitchens, and laundries and black water is the waste water from toilets and is contaminated with faeces and urine.
Characteristics of Household Grey Water
There are essentially three different types of grey water:
1. Bathroom grey water from the bath, basin and shower. This is about 55% of the total grey water volume produced in a household.
2. Laundry grey water, which contributes about 34% of the total grey water volume.
3. Kitchen grey water, which contributes about 11% of the total grey water volume. Each of these types of grey water can contain quite large quantities of dissolved soaps, detergents and scents.
Typical Composition of Grey Water
In addition to the chemical and physical properties shown in this table, the microbiological quality of grey water is extremely important for its potential as drinking water. Microorganisms, which typically grow in the intestines of warm-blooded animals including humans, are present in the millions per gram of faeces. Faecal coliforms, sometimes called thermotolerant coliforms, are described as colony forming units (cfu) per 100mL.
These microorganisms, and a high faecal coliform count, are undesirable and indicate a greater chance of human illness developing as a result of contact with the waste water.
