By: FWI Staff Writer Grey water, also spelt as gray water, grey water or gray water and also known as 'sullage', is wastewater generated from processes such as washing dishes, laundry and bathing. Sometimes, the term excludes kitchen wastewater containing significant food residues. It is quite distinct from black water in the amount and composition of its chemical and biological contaminants. Grey water gets its name from its appearance and possibly also from its status as neither being fresh (groundwater or potable water), nor heavily polluted (black water). From the point of view of treatment and pollution prevention, grey water decomposes much more quickly and is easier to treat and eliminate than black water, but is still considered to be a health and pollution hazard if released into the natural environment untreated. In recent years concerns over dwindling reserves of groundwater and overloaded or costly sewage treatment plants has generated much interest in reusing or recycling grey water, particularly for use in irrigation. However, concerns over potential health and environmental risks means that many jurisdictions demand intensive treatment systems that are so expensive they usually cost more than simply treating and buying the tap water they save. Treatment methods and risks are poorly researched and understood by authorities. Despite this, grey water is often reused for irrigation, illegally or not, in drought zones or areas hit by hose pipe bans, typically by manual bucketing. In the third world, reuse of grey water is often unregulated and is common. At present, the recycling of grey water and its risks are poorly researched compared with its elimination. Grey water comprises 50-80% of residential "waste" water. It may be reused for other purposes, especially landscape irrigation. The benefits of grey water reuse can include: • Lower fresh water use • Less strain on failing septic tank or treatment plant • Grey water treatment in topsoil is highly effective • Ability to build in areas unsuitable for conventional treatment • Less energy and chemical use • Groundwater recharge • Plant growth • Reclamation of otherwise wasted nutrients Grey water typically breaks down faster than black water and has much less nitrogen and phosphorous. However, all grey water must be assumed to have some black water-type components, including pathogens of various sorts. Copyright 2006 Fine Water Imports Inc. All Rights Reserved