There may be a number of reasons a homeowner would choose not to use graywater. Here are some key issues to remember:

Transcription

1 Graywater Recycling Forrest Cobb 1, Calvin Finch 2, Jose RodolphoValdez-Barillas 3, Mike Martin 4 On April 11, 2014 Governor Rick Perry declared many Texas counties, including Bexar County, to be in excessive drought conditions. The Edwards Aquifer Authority has recorded near historic lows for 2013 while the U.S. Drought Monitor shows that an average of 91% of Texas was experiencing abnormally dry conditions for that same year. The state climatologist John Nielsen-Gammon predicts that these conditions could last to the end of the decade. In an effort to conserve water, the Texas Senate and the Texas Commission on Environmental quality have developed rules and regulations to encourage safe and efficient graywater use. Harvesting graywater is an excellent way to reduce the amount of freshwater used for landscape irrigation while lowering monthly water bill and sewage charges. However, in order for graywater reuse to be beneficial, a homeowner must assess what type of graywater he or she is producing, what type of system to install, and how much the system will cost versus how much savings will be gained. What is graywater? Graywater is waste water from: hand washing sinks showers washing machines It is not waste water that comes into contact with toilet waste, human excreta, or sinks used in food preparation. According to a study done by the Water Environment Research Foundation in 2012, graywater can constitute almost 50% of all wastewater generated by a household. When should I use graywater? Recycling graywater conserves potable water without sacrificing home landscapes and gardens. Homeowners who want to help conserve Texas water, and can follow the best management practices (BMPs) listed in this document, should consider using graywater for landscape irrigation. Any residential reuse under 400 gallons a day requires no permit, and graywater systems like the Laundry to Landscape system can be simple to design and install. When should I not use graywater? There may be a number of reasons a homeowner would choose not to use graywater. Here are some key issues to remember: Graywater should not be used from washing machines if any fecal matter is washed, for example from cloth diapers. 1 Undergraduate Biology Student Texas A&M San Antonio; 2 Director of the Texas A&M Water Conservation & Technology Center; 3 Professor of Biology at Texas A&M San Antonio; 4 Texas A&M Engineer

2 Graywater should not be used if pollutants like paint, industrial cleaning products, dish detergents containing high salts and boron, food waste, or chlorine bleach are present. Graywater should not be used if water is treated with water softeners that use brine as this will harm the plants and soil being irrigated. To see whether or not graywater will work for you, read the BMPs in the following sections or use the additional resources listed at the end of the publication. What type of Graywater system should I build? There are many types of graywater systems which range from very high tech to very simple. What system an individual homeowner uses should be based on the type of graywater to be used, shower, sink, or laundry. Every graywater system is different and should be designed to fit an individual homeowner s needs. The goal of the system is to conserve as much water as possible while keeping a healthy landscape and garden. However, a homeowner has to look at the cost of installing a graywater system. Harvesting graywater might not make sense if too much money is spent building the system. Texas A&M engineer Mike Martin states, a good rule of thumb is that expected savings will be between $5-$25 a month, depending on the family size and how many graywater sources are used. A two year payback on your investment is a reasonable expectation. Graywater systems can range from expensive and high tech systems like the sand filter to drip irrigation system, to the affordable and low tech laundry to landscape and branched drain systems. As a graywater system becomes simpler its cost is reduced because of savings in materials and labor. The more work a homeowner can do by him or herself, the cheaper the system will be. For more information on the different types of graywater systems to install, Art Ludwig s books listed in the resources section are an excellent reference. For information about graywater regulations in your area, contact your local A&M extension agent or the Texas A&M Water Conservation & Technology Center. The Laundry to Landscape System One of the simplest and most reliable systems that a homeowner can install is the Laundry to Landscape system. Texas A&M Agrilife Extension in conjunction with the Texas A&M Water Conservation and Technology Center, and the Texas Center for Applied Technology has designed and installed a graywater demonstration garden that uses wastewater from a laundry machine to water two raised garden beds. The garden is located at the Mitchell Lake Audubon Center and can be viewed whenever the center is open. The price of this system without labor costs is estimated to be around $285. Cost can change depending on whether or not a pump and surge tank are used, and how much piping must be used to distribute the graywater. The description provided here should give homeowners a good idea of how the system works and what a legal graywater system should look like, but there are many different ways to deliver graywater to your landscape. The Laundry to Landscape system is the cheapest most reliable

3 system that has fail safes against clogged lines and won t burn out your washing machine pump; it was originally designed by Art Ludwig of Oasis design. Figure 1. Simple Diagram of the Laundry to Landscape System, by Fred Wood A diverter valve is installed so that water can be sent to either the sewage collection system or to irrigate the landscape. This ensures that if the system needs to be repaired, or if any pollutants like bleach are in the graywater, that the homeowner still has the option to direct graywater to the sewer. When the diverter valve is set to irrigate it will flow into the surge tank. The surge tank should be big enough to hold at least one full load of water. This will ensure that the system is not overloaded and that graywater flows steadily into the landscape without pooling. The pipe should discharge just above the surge tank to make an air gap. The air gap serves the dual purpose of acting as a vacuum gap so that water is not siphoned from the washing machine as it fills while also preventing backflow into the washing machine. A filter sock should be attached to the end of the pipe to filter out lint, hair, and other detritus that might clog the system. Pantyhose are a cheap and readily available filter sock which can be routinely cleaned or discarded as necessary. Depending on the distance the graywater has to travel and how high the surge tank is, a pump may need to be installed. From the pump in the surge tank, graywater will run into the receiving landscape or garden. It is very important that graywater be deposited directly into the soil. Two ways of distributing the graywater are the drip line method and the mulch basin. The drip line is created by drilling holes at regular intervals in the piping; this allows water to seep out at a slow constant rate. The mulch basin is made with an inverted plastic flower pot that has holes drilled in it, irrigation piping runs into the flower pot and deposits graywater inside so that water is released down near the plants root systems. Because the piping and flower pot are buried in mulch, there is no risk of spraying graywater in the air or of losing water through evaporation. With this system, a homeowner can put their waste water to good use. Energy Star lists the average washing machine as using between gallons per load, and the average amount of loads done per year by a small family as 300 loads. That means that a graywater Laundry to Landscape system could be irrigating with 6,000 gallons to 12,000 gallons per year of water that would otherwise be sent down to the sewer. General Best Management Practices These best management practices (BMPs) will help homeowners maintain a properly functioning and legal graywater system. Most of these rules are designed to ensure that graywater is delivered into the soil as quickly as possible while avoiding contamination of the soil with pollutants. These graywater BMP s come from the rules and regulations of both the Arizona and Texas Commissions on Environmental Quality: Avoid excessive contact with graywater or graywater irrigated soil.

4 Surface accumulation of graywater should be kept to a minimum. Graywater should not pool, form puddles, or run over property lines. Graywater should always be applied directly to soil, never sprayed in the air. It is generally recommended that graywater be used for landscaping plants, however if a vegetable garden is irrigated, special care should be taken to prevent graywater from touching any part of the plant that will be eaten. Graywater should not be used in a wash or drainage area to avoid contaminating the local water shed. Cover or secure outlets and surge tanks to prevent mosquito and rodent infestation. Tanks and lines containing graywater should be clearly labeled as non-potable. Water used to clean diapers or that otherwise comes into contact with feces should not be reused. Graywater should not contain toxic chemicals from activities such as cleaning car parts or washing greasy, oily rags. Graywater systems should be designed so that any backups can be directed to the sewage collection system. Untreated graywater should not be stored, temporary storage in a surge tank or for transportation are acceptable but the sooner graywater is applied to soil, the better. Solids like lint or hair should be filtered out of graywater to prevent the system from clogging. Resources and References Texas A&M Water Conservation & Technology Center wctc.tamu.edu Tel: ext. 240

5 Texas Graywater Law Texas Senate. 78 th Legislature. HB 2661, Relating to the use of graywater, (2003) Texas Commission on Environmental Quality Rules and Regulations Use of Graywater systems, TAC 30 Chapter 210 subchapter F (2005). Disposal of Graywater, TAC 30 Chapter 285 subchapter H, (2005). Suggested Reading Material 1. Little, V. (2001). Graywater Guidelines, Tuscon, AZ, Water CASA 2. Ludwig, Art. (1995). Builders Greywater Guide. Santa Barbara: Oasis Design 3. Ludwig, Art. (2006). Create an Oasis with Greywater. Santa Barbara: Oasis Design 4. Roesner Larry, Dr. Yaling Qian, Dr. Melanie Criswell, Mary Stromberger, Dr. and Stephen Klein, Dr. (2012). Long Term Effects of Landscape Irrigation Using Graywater. Water Environment Research Foundation. WERF. Retrieved April 23, 2014 from < Acknowledgments and Disclaimer Roel Lopez, Director of the Texas A&M Institute of Renewable Natural Resources Texas Water Resources Institute, and Angelica Lopez, Research Scientist with the same institute provided guidance and editorial comments for this publication. Fred Wood produced the illustration of the Graywater system. This publication has been funded by the U.S. Department of Agriculture through the Outreach and Assistance for Socially Disadvantaged Farmers and Ranchers program. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the USDA.