HOW CAN GREY-WATER USAGE HAVE AN IMPACT ON REDUCING CHEMICAL DUMPING DOWN HOUSEHOLD DRAINS?

Simply dumping a household chemical down the drain gets rid of it, right? While it may feel good to get rid of the chemical, you may have just given your community and local environment a bigger headache. How you say? By getting a quick grasp on the concept of "grey-water," you should quickly understand the seriousness of household water waste.

Greywater, sometimes spelled graywater, grey water or gray water and also known as sullage, is non-industrial wastewater generated from domestic processes such as washing dishes, laundry and bathing. Greywater comprises 50-80% of residential wastewater. Greywater is distinct from blackwater in the amount and composition of its chemical and biological contaminants (from feces or toxic chemicals). Greywater gets its name from its cloudy appearance and from its status as being neither fresh (white water from groundwater or potable water), nor heavily polluted (blackwater). According to this definition wastewater containing significant food residues or high concentrations of toxic chemicals from household cleaners etc. may be considered "dark gray" or blackwater.

In recent years concerns over dwindling reserves of groundwater and overloaded or costly sewage treatment plants has generated much interest in the reuse or recycling of greywater, both domestically and for use in commercial irrigation. However, concerns over potential health and environmental risks means that many jurisdictions demand such intensive treatment systems for legal reuse of greywater that the commercial cost is higher than for fresh water. Despite these obstacles, greywater is often reused for irrigation, illegally or not, in older rural construction, simple construction old and new, often consisting of nothing more than a "drain out back" (pipe pointed down the nearest hill) and in drought zones or areas hit by hose pipe bans, typically by manual bucketing. In the third world, reuse of greywater is often unregulated and is common. At present, the recycling of greywater is poorly understood compared with elimination.

Domestic wastewater plumbing is usually combined at the sewer, so that grey and black waters are removed together using a shared sewerage system.

Domestic wastewater plumbing is usually combined at the sewer, so that grey and black waters are removed together using a shared sewerage system. Sewage water can then be treated to limit pollution and health risks, before being returned to the environment at large. The majority of greywater ends up as effluent in rivers and oceans in this way. Despite treatment, this arguably results in greater contamination of natural waters, as the natural purification capacity of surface water is millions of times less than that of soil. Simply dumping greywater on the soil, from an ecological standpoint, is less damaging than sending highly treated greywater directly into natural waters.

The first step in utilizing the concept or grey-water is to recycle as much organic material as possible, keeping it away from waste disposal systems altogether. We can eliminate all blackwater from our drains by composting all human manure and urine. We can also eliminate almost all other organic material from our drains by composting food scraps. As such, one should never use an in-sink garbage disposal. As an indication of how much organic material typically goes down a household drain, consider the words of one composting toilet manufacturer, "New regulations will soon demand that septic tanks receiving flush toilet and garbage disposal wastes be pumped out and documented by a state certified septage hauler every three years. When toilet and garbage solids and their associated flush water is removed from the septic system, and the septic tank is receiving only graywater, the septic tank needs pumping only every twenty years." According to the US EPA, household garbage disposals contribute 850% more organic matter and 777% more suspended solids to wastewater than do toilets.

If collected using a separate plumbing system to blackwater, domestic greywater can be recycled directly within the home and garden. Recycled greywater of this kind is never clean enough to drink, but a number of stages of filtration and microbial digestion can be used to provide water for washing or flushing toilets; relatively clean greywater may be applied directly from the sink to the garden, as it receives high level treatment from soil and plant roots. Given that greywater may contain nutrients (e.g. from food), pathogens (e.g. from your skin), and is often discharged warm, it is very important not to store it before using it for irrigation purposes, unless it is treated first. There are numerous "soft" processes based on natural biological principles such as using reedbed filter systems, the wetpark systems or the living wall that can be used to clean up greywater.

There are also "hard", direct processes, such as distillation (evaporation) which need not necessarily be as energy intensive as they might initially appear. There seem to be no commercially available "hard" greywater recovery devices suitable for on-site use in the individual household, even though a number of such technologies exist. Some municipal sewerage systems recycle a certain amount of grey and black waters using a high standard of treatment, thus providing reclaimed water for irrigation and other uses. All in all, it is the increased perception that every drop of water used in the household may have a future benefit for the environment if properly managed, or a possible detriment for the environment if not properly treated. One must remember that simply dumping anything down the drain doesn't get rid of the chemical or waste. It may actually cause an environmental problem somewhere else in their community.