Grey Water Marsh

Protect Health With Grey Water

Select Garden Friendly Soaps

Certain types of plants that grow great and not so great with Grey water

The Future Of Grey Water

Our Earth has been scientifically proven to have more water then land, seventy-five percent is water while the other twenty five percent is covered in land mass. It has also been approximated that there is three hundred and sixty billion billion gallons of water (1.36x1018 m3). However when we consider the water actually available for use, the amount is reduced drastically. Unfortunately, over ninety nine percent of surface and groundwater is not very accessible, so we are forced to rely on less then one percent of water on Earth for use. This is only one example why it is important to find and implement new sources of water and maintain the quality of existing supplies, even though it can be both strenuous and expensive. With only less then one percent of the entire world water supply to rely on, these tasks are necessary for human and environmental health.

In California, large-scale agriculture and expanding metropolitan areas have caused the state to seek for water outside its borders. As more pressure is put on existing resources, wastewater recycling is being explored. Grey water recycling is one conservation procedure that can be integrated into neighborhoods or individual houses. California law states, “Grey water includes waste water from bathtubs, showers, bathroom wash basins, clothes washing machines, and laundry tubs, but does not include waste water from kitchen sinks or dishwashers” (California Water Code 14876 1992). Recycling Grey water, which makes up sixty percent of residential wastewater (Ingham, 1980), would significantly reduce household water consumption.

The Campus Center for Appropriate Technology (CCAT) at Humboldt State University in Arcata, California has decided to get involved with this new idea in reusing wastewater. CCAT is in the process of designing a model for treating household Grey water. The concept is to catch and treat sink and shower water in a socially and environmentally responsible way, and to reuse the water and nutrients on site. CCAT is meeting

the challenge to reincorporate our waste materials back into the cycle instead of throwing them away. This experiment is known to be an excellent tool to use for reusing and saving precious water and can be implemented in any area big or small.

In CCAT's system, Grey water first drains into a filter from both the sink and shower and trickles down into a primary settling tank. Large parts of garbage are buried in the ground because they do not break down easily. With a lid above ground food particles and grease gets filtered into a mesh net and then settles. Oils and grease are lighter than water and collect at the top of this tank and then is skimmed off on a weekly schedule. This process is shown in the picture on the left.

Filtered Grey water then enters a distribution tank for entry into one of the two marsh treatment systems. The first system constructed in 1985 consists of a three- chamber under-gravel marsh. The second system, constructed in 1991 consists of a three-chamber under-gravel marsh. These marsh systems are the heart of the treatment process. The open water marsh’s chambers are stair-stepped downward slightly, allowing gravity to put the water through them. Wooden dividers separate the chambers, forcing the water to weave over and under them in a slow journey. Each chamber is filled with fine gravel to six inches of the water surface. The under-gravel marsh is constructed also identical to the open water marsh. Difference is additional gravel is added to completely cover the water surface by about three inches. Water is distributed uniformly across the surface of each chamber by a perforated pipe system. The pump below then pumps out clean and reusable water, which can be used, for gardens, like the two examples shown here below.

          

Open water Marsh                             Under-gravel Marsh

         

Protect Health from Grey water-

            The threats come in two classes, chemical toxins (from cleaners) and microbiological. Both can be concern to people, and chemical toxins can harm plants and soil. This subject can be found in more depth at Create an Oasis with Grey water. If a member of a household is ill, Grey water may carry infectious bacteria or viruses. However, in order for the Grey water to make another person ill that person would have to drink or otherwise consume the contaminated Grey water. As long as a person does not drink the Grey water or irrigate vegetables with Grey water and then eat them unwashed, Grey water is safe. The Grey water Standards require that Grey water not surface and that human contact with Grey water be avoided. Grey water systems designed, installed, and maintained in accordance with the standards present minimal risk to public health. The California Department of Health Services participated actively in the development of these standards to insure the protection of public health. 

…        Do not drink or play in Grey water.

…        Do not mix potable (drinking) water with Grey water.

…        Do not allow anything that may be eaten to come into contact with Grey water.

…        Do not allow Grey water to pond on the surface or run off the property.

Select garden-friendly soaps

            The chemical and biological composition of Grey water varies greatly, based on numerous factors, including the original quality of the water coming to your home, the personal habits of the family members, which plumbing fixtures are connected to the system, and the soaps used. Since the type of detergent you select is one major factors that you can control, the use of garden friendly soaps can contribute significantly to better quality Grey water. The more arid the climate, the higher the percentage of irrigation under which is Grey water, and the more clay there is in the soil, the more critical this is. Most hand and dish soaps and shampoos will not damage plants in low residential concentrations. Laundry detergents, on the other hand, need to be selected carefully. Sodium and boron are chemicals that can have a negative effect on landscapes. Powered detergents and soaps include “filler” ingredients (not essential to clothes cleaning) that are usually some compound of sodium. Liquid soaps contain few fillers, thus less sodium. Here are a couple of tips to follow when dealing with Grey water.

…        Avoid washing more often or using cleaner then needed.

…        Avoid cleaners that contain boron (borax), a potent plant toxin.

…        Avoid using chlorine bleach or non-chlorine bleach containing sodium perborate. Liquid hydrogen peroxide is a less powerful, more expensive, but not non-toxic alternative bleach.

…        Use cleaners that contain little or no sodium. Liquid cleaners and laundry detergents typically contain less sodium than powders. A build-up of sodium is toxic to plants and destroys the structure of clay soils.

…        Use biocompatible cleaners. Oasis Biocompatible Cleaners are specifically designed and tested for the irrigation of plants. They biodegrade into plant nutrients. They contain no sodium, chlorine, or born and do not adversely affect soil pH or structure.

Certain types of plants-

            Sodium, potassium and calcium are alkaline chemicals. Because of the presence of these chemicals in laundry detergent, Grey water use tends to raise alkalinity of the soil. Slightly alkaline soils will support many garden plants. Even most acid-soil loving plants will be happy with slightly alkaline soils that are generously amended with organic matter. The pH of an acid soil is 6.9 or lower while that of an alkaline soil is 7.1 or higher. If a simple pH test indicates that the pH reading is over 8.0, the pH should be reduced. This can be accomplished by adding agricultural sulfur or an acidifying fertilizer such as ammonium sulfate. A sandy, well-drained soil will be less affected by the application of Grey water than a poorly drained clay soil. Sometimes Grey water may degrade the structure of a clay soil by making it stickier and less loamy. The soil’s physical condition also may be affected by high sodium. To correct these problems and keep soil healthy, once again, till in organic matter. The salts that might build up from the use of Grey water will only be a problem if they are not leached away periodically by heavy rains. If winter rains are light, occasionally leach the soil with fresh water.

            The application of too much water, of any kind, too frequently will result in saturated soils, and an invitation to plant disease. Generally, plants are healthier when the soil is allowed to dry out between irrigations. A very small percentage of plants may be damaged by Grey water, most of these are listed below. Too much sodium or chlorine could result in leaf burn, chlorosis (yellow leaves), and twig die back. Boron can be toxic to plants at levels only slightly greater than is required for good plant growth. Symptoms of boron toxicity include leaf tip and margin burn, leaf cupping, chlorosis, branch die back, premature leaf drop, and reduced growth.

            Plants that are especially high sodium and chloride which may be present in Grey water are-

           
Plants that grow well with Grey water-

Difficult plants to grow with Grey water-           

Future of Grey water-

            In the future, expect greatly expanded water recycling practices and options for legal Grey water use. Already car washes and many industrial processes purify their wastewater, and then reuse it again for the same purpose. Reclaiming treated sewage for irrigation is exploding in popularity in the U.S. In Europe, highly treated sewage is pumped back into the potable water system. These systems take considerably more energy, chemicals and infrastructure than on-site reuse of untreated or partially treated Grey water. As resource constraints tighten, home Grey water systems will improve in efficiency, ease of maintenance and popularity. In the future such systems, illegal everywhere just six years ago, will be mandated for construction and use worldwide.

            Taking full responsibility for the small amount of the global water cycle that flows through an individual home can make a person feel like they are resourceful and contributing to saving the water that all people use worldwide. While, on the other hand, some might feel that the Grey water system is to tiny in its process of saving water because it focuses on used shower and sink water only. Put into prospective though of how many people we share our water with approximately 6.2 billion individuals, if no ideas of saving water is implemented soon in the future there will be no more water for humans or ecosystems to thrive upon. This would be a bigger problem to try to solve, so saving water makes sense even if it is just a small part. If anyone has questions or comments about the project be held at CCAT anyone can notify me at sfg3@humboldt.edu

 

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