Gray Water Systems: Recycling Water for Home and Farm

The Global Freshwater Crisis

As the world's population continues to grow, there will be an ever greater need for potable, or purified, water. Most people are completely unaware of just how serious the problem of global water consumption is, because they never think past turning on their sink or sprinkler system. Take into consideration the demands placed on the water supply by less obvious factors such as livestock and farming. There is an economy of scale: those massive agricultural irrigation systems that draw water out of rivers, lakes, streams, and ponds consume enormous amounts of water that cannot then be used for any other purpose. Farms, cities, industry, and the many other levels of human consumption place a great deal of pressure on the natural water cycle. Globalization has actually increased the demand for water and has pushed many regionally dry areas into even worse water deficits. For example, "industries and communities located in cold regions often face different challenges in treatment of wastewater from those of warmer regions" (Gao, Smith, & Sego). Unfortunately, the world has yet to create an economical or cost-effective method for converting the vast amounts of ocean and seawater into usable drinking water.

The world's supply of fresh water — that is, water that is salt-free, pollution-free, or not locked in the form of ice — must be considered a finite resource, more akin to commodities such as oil or coal. When fresh water runs out, obtaining more will be extraordinarily difficult. That realization brings to light the necessity of recycling the water we use. "Production of drinking water and wastewater treatment are two essential steps of the water cycle" (Guillaume, Lorain, Azouni, & Aurelle). Recycled water can fill a large need if it is properly captured, cleaned, and then appropriately reused. The first step is to capture the various sources of sullage. Gray water systems do just that — they capture already-used water so that it can be reused.

We have a few viable options for purifying and reconditioning water in ways similar to what nature does on its own. "Suspended and dissolved impurities present in naturally occurring water make it unsuitable for many purposes. Objectionable organic and inorganic materials are removed by such methods as screening and sedimentation to eliminate suspended materials; treatment with compounds such as activated carbon to remove tastes and odors; filtration; and chlorination or irradiation to kill infective microorganisms" (WA.Gov, 2005). Of course, nature has had a considerable head start in purifying water — this process has been ongoing for millions of years, while human technology in this area is relatively recent. An excellent solution when it comes to reusing water is the implementation of gray water systems.

What Is Gray Water and How Are It Captured?

Gray water systems are water recycling processes that capture already-used water — known as gray water — and make that water available for future reuse. Consider the typical daily use of a residential water supply. Water is either pumped into a house from a municipal water company or drawn from a public or private well. Once water is in the home, the consumer washes dishes by hand or in a dishwasher, launders clothing by hand or in a washing machine, the family bathes periodically, and everyone regularly flushes the toilet. All of these processes occur normally without any consideration of the water cycle. These patterns of water use limit both the community's and the world's supply of fresh potable water because the water follows a use-once-and-discard life cycle.

To illustrate this cycle, consider that once a washing machine finishes its final spin, the water used for that wash cycle drains directly out of the home into the sewer system. "The water that flows down your showers, bathtubs and washing machines is known as gray water and has historically been destined for the sewer" (Greenlink). Gray water, then, is water that has just been used; gray water systems are processes that recapture this water before it enters the sewer, with the intent of recycling it. "To conserve diminishing water supplies and curb rising water costs, Brac Systems has created a self-contained, low-maintenance system that captures your gray water, filters it and reuses it for irrigation or your toilet evacuation system" (Greenlink). The recaptured water may not be potable, but there are many other uses for semi-clean water.

Residential Gray Water Systems

Adding water recycling units to residential homes is a logical step. "As lakes shrink and droughts worsen, people all over the world are realizing that our freshwater supply is limited and must be protected. In the United States alone, experts predict that at least 36 states will face serious water shortages within the next five years" (Greenlink). By capturing and reusing a residential property's gray water, millions of gallons of fresh water could be saved annually. Consider that every time someone in a home completes a load of laundry, a water recycling process could take that water and redirect it to the toilet for the next ten or more flushes.

However, the majority of water usage in residential settings is actually lost outside of the home. "Atlanta Water Harvest recommends the use of recycled grey water for landscape irrigation. It is especially practical for lawn and garden maintenance, which can account for nearly 50–80% of a homeowner's summer water usage" (Atlanta Water Harvest). Gray water reuse for landscape irrigation represents one of the most impactful ways households can reduce their freshwater consumption.

Residential gray water systems that have been created and tested around the world have also shown unexpected benefits in surprising areas. "An Integrated Water, Energy and Sanitation Solution (IWESS) has been proposed as a sustainable way of utilizing natural resources through a concept that turns waste into a resource, thereby taking advantage of what is currently considered problem sources and converting them into useful inputs" (Odhiambo, J.O., et al.). A notable added benefit of residential gray water systems is that they help local and municipal wastewater systems achieve volume relief. Currently, wastewater systems are frequently overwhelmed because they receive too much gray and black water flow from the residential communities they serve. "Not only does gray water recycling reduce the burden on your local freshwater supply, it also lessens the strain on wastewater systems. It's a smart, simple step in the right direction, one that begs the question: why haven't we thought of this sooner?" (Greenlink).

Conclusion

These systems can be used just as efficiently as any direct river, stream, or pond irrigation system. The key is to capture all runoff, utilize better-designed rain and wastewater capturing systems, and then provide a viable solution for supplying irrigation equipment. Combining more efficient farming techniques with the use of recycled water could go a long way toward preserving the world's finite freshwater supply for generations to come.