“The average annual rainfall across the entire national ...
Femke Love Oldham
3 April 2008
RAINWATER HARVESTING AND RURAL DEVELOPMENT: THE POWER OF THE CIDECALLI PROTOTYPES
INTRODUCTION
“The average annual rainfall across the entire national territory of Mexico is 1,500 cubic kilometers of water. With only 3% of this quantity, there is the ability to supply 13 million people and 50 million animals with clean water. Additionally, this small percentage of the total rainfall would irrigate 18 million hectares of crops.”[1]
The broad and somewhat surprising potential of rain motivated the creation of the International Center for Demonstration and Training in Rainwater Harvesting (CIDECALLI). Worldwide, there is a growing realization that water is an integral factor to the sustainable development. Policy-makers and activists are recognizing that a clean and constant water supply is a human right and demanding that adequate water be made available to everyone. With this goal in mind, a team of professors and engineers at the College of Postgraduates (COLPOS) in Montecillo, Mexico State partnered with the Autonomous University of Chapingo (UACh) and the Autonomous University Antonio Narro (UAAN). This team discovered that rainwater represents a viable option for mitigating the grave reality faced by over 1 billion people on the planet currently living without access to clean and safe water supply.[2] In 2004, The CIDECALLI team began working to create a set of rainwater harvesting prototypes with the intent of alleviating growing water concerns within Mexico and abroad.
INTERNATIONAL PRECEDENTS
An international precedent for rainwater harvesting does exist. In countries around the world, systems for rainwater capture are being implemented and used successfully to provide humans with clean water. While these systems have made the biggest impact in smaller, rural communities, they are functioning successfully in large cities as well. Rainwater harvesting can have a great social, economic and environmental impact; but it is also a competitive water alternative and can provide a source of work and business within a community. These systems can be easily designed and adapted to a diverse array of ecological conditions.
Examples abound of rainwater harvesting on the international scale. In Bangladesh, many communities have resorted to collecting rainwater in above and below ground cisterns due to arsenic contamination in freshwater aquifers. These community projects were successful enough that the government took charge in 1997 and since then has implemented more than 1,000 cisterns, the majority of which are located in rural areas. In India, where drought is a devastating reality for almost half the population, various cities have initiated extensive rainwater harvesting campaigns to help supply water to those in need. Similar examples can be found throughout Asia – in Japan, China and Thailand, for example; rainwater harvesting is a well-known technique for combating unreliable or contaminated water sources. Recently, Sri Lanka went one step further and established the first national policy of rainwater harvesting. Other examples of rainwater harvesting exist in countries such as Brazil, Spain and Turkey. [3]
In the United States, Texas has taken the lead in rainwater harvesting by creating and publishing a manual for the development and use of cisterns and other systems for capturing rainwater in order to solve problems with water scarcity. The Texas Manual for Rainwater Harvesting provides a wealth of useful information for citizens interested in all aspects of rainwater harvesting while making a case for the use of rainwater. For example, it points out that rainwater has a nearly neutral pH and is valued for its softness and purity. In addition, rain is free from most salts, minerals, natural and man-made contaminants because it never hits the ground and thus rarely comes into contact with sources for contamination before being captured.[4] Additionally, due to the difficulty of maintaining a watershed large enough to support island populations, the U.S. Virgin Islands has mandated the use of rainwater harvesting systems by law.
International evidence shows overwhelming support for rainwater catchment systems as an efficient and dependable source of water. However, most systems currently in place cannot supply a high enough quality of water for human consumption due to a lack of secure methods for purification. It is this prevalent shortcoming of modern-day rainwater harvesting systems that makes the CIDECALLI prototypes innovative. The center’s prototypes seek efficiency in terms of both quantity and quality of water.
THE INTERNATIONAL CENTER FOR DEMONSTRATION AND TRAINING IN RAINWATER HARVESTING (CIDECALLI)
In 2004, the team of professors and engineers that founded CIDECALLI quantified its goals regarding water quality and quantity into a specific set of objectives. The first objective is to promote a variety of uses for rainwater. These uses include purified rainwater as a source of drinking water, and the use of filtered rainwater for forest, animal, and crop production in greenhouses, as well as distilled rainwater for industrial use. The center’s second objective is the optimization of water resources. More specifically, it seeks to reduce reliance on wells and groundwater aquifers as the primary source of water in order to offset current trends of overuse and destruction of groundwater resources. The final objective of the center is based on the recognition that rainwater lacks the minerals often found in groundwater aquifers. The center seeks to improve the rainwater by adding folic acid, fluoride, vitamins and minerals in order to ensure that the water has multiple health benefits for target communities.[5]
To implement these objectives, the center selects target communities for the projects, based almost solely on need. CIDECALLI literature cites the four most at-risk populations as: female heads of house, senior citizens, families with school-aged children, and families with young children (aged 0-6).[6] Communities with high numbers of at-risk populations are prime targets for the projects. In addition, projects are based on the success of mobilization efforts and location of the community. It is important to note that annual rainfall rate does not appear to be an overwhelming factor in the selection or success of the projects. Manuel Anaya Garduño, director of CIDECALLI with more than 30 year’s experience in rainwater harvesting research and development, asserts that these projects have been designed with enough flexibility to adapt to an array of ecological conditions. He teaches visitors that the most important factor in community selection is a desire to implement the project among the target community members.[7] José María Suárez Dueñas, an expert in rural development from the Honorary Commission on Shared Irrigation (FIRCO), agrees with this principle and adds that if no desire for development and change within a community exists, then efforts to enter that community have little chance for success regardless of rainfall levels.[8]
To ensure the success of its projects, the center seeks to generate well-developed and efficient technologies and to make information available through courses and workshops in rainwater harvesting, through the facilitation of interest groups, and through project tours.[9] To further disseminate knowledge and to promote its rainwater harvesting objectives, CIDECALLI holds two certification seminars each year on rainwater harvesting. These seminars cover a broad range of topics related to rainwater harvesting such as purification standards, financial concerns, and materials and construction costs. Additionally, participants are required to present a fully-formulated and detailed example of a rainwater harvesting project to be reviewed by a panel of CIDECALLI experts. Upon completion of the seminar, participants are certified as fully competent in applied design and construction of rainwater harvesting systems.[10]
COMPONENTS OF RAINWATER HARVESTING SYSTEMS
To better understand the CIDECALLI prototypes, a brief explanation of the basic components of a rainwater harvesting system is helpful. Most rainwater harvesting systems are comprised of four basic components: a catchment surface, a conduction system, storage area or tank, and a system for filtration and treatment.[11]
The catchment surface is defined as the collection area on which the rain falls. The surfaces used for this purpose are the roofs of houses, schools, businesses, greenhouses, as well as natural slopes on hillsides covered with impermeable material. The most important consideration for a catchment surface is its base material – that is, it must not give off odors, colors, or other substances that could contaminate the rainwater and interfere with the treatment process.[12] The materials used for this construction are metals such as steel. Concrete, clay, and slate, if used, are all coated with some sort of non-toxic laminate.[13]
The conduction system refers to the combination of gutters and downspouts which carry captured rain from the catchment surface to the storage area. Gutters often run along the perimeter of a roof and are typically made of half-round PVC pipe, seamless aluminum or galvanized steel.[14] It is important that the use of lead is avoided as it is a very harmful contaminant. The open top end of these gutters are usually capped with a mesh screen in order to block leaves, twigs, garbage and other debris from entering the storage area. Gutters are connected to a downspout pipe, fastened to the side of the building, which lets the water flow into the storage tank.[15]
The storage area or tank is usually the most visible component of the rainwater harvest system and are generally in the form of cisterns or tanks made of plastics (fiberglass, polypropylene, PVC), metals (galvanized steel), wood, or concrete.[16] The size of the tank is a function of the amount of precipitation, demand, the projected length of dry spells, the catchment surface area, aesthetics, personal preference, and budget.[17]
THE CIDECALLI PROTOTYPES
To date, CIDECALLI has designed and constructed five different model systems for rainwater harvesting. All are located on the Montecillo campus of the College of Postgraduates, and are aptly named COLPOS 1 – COLPOS 5. All of the prototypes except for COLPOS 3 are designed to service a single family. Due to the difference in scale, COLPOS 3 will be discussed in a separate section below.
COLPOS 1 is a system for domestic use. It is attached to a single family home and features a cistern 73 cubic meters in size. This system is meant to supply potable and purified water to four people based on a per capita consumption of 100 liters (26.4 gallons) per day. The area of the catchment surface for this model is 120 cubic meters and the annual precipitation is calculated at 610 millimeters (approximately 24 inches). This prototype uses a series of purification methods that includes the “Speedy” filter, an auto-cleaning apparatus that eliminates particles, as well as a carbon active filter that disinfects and softens the water. The water is then sent through a set of micro-polishers meant to reduce and eliminate the particulates in the water. These polishers take the form of filters that are 20 and10 microns in size. They eliminate visible impurities in the water and make it fit for human consumption.[18] The total cost for future construction of this project is estimated to be $3,800 USD, all inclusive.[19]
[pic]
COLPOS 1 diagram[20]
COLPOS 2 is designed to supply enough water for a tank to harvest fish as well as for irrigating a family orchard. This project includes a catchment area, conduction system and storage area for rainwater as well as an area specially designed for harvesting fish to be used for consumption as well as for adornment. The fish storage systems feature floating cages. An alternative use of the water in the storage tank is for irrigation of a family orchard containing medicinal plants and other crops that can help supply a family with vitamins and minerals. The byproducts from such an orchard can be used for animal consumption as well as the creation of a compost system. The estimated cost for this system is $24,500 MXP ($2,450 USD)[21]
[pic]
COLPOS 2 diagram[22]
These two prototypes are aimed at fulfilling water requirements associated with small-scale agriculture. Both of these prototypes contain a basic purification system that filters down to 100 microns.[23] COLPOS 4 is a model for a livestock trough capable of serving a family farm. This model provides high quality water for a herd or flock of animals in order to satisfy their basic needs for consumption – approximately 50 liters per animal per day. This model has a capacity of 500 cubic meters and has an estimated construction cost of $4,000 USD.
[pic]
COLPOS 4 diagram[24]
COLPOS 5 is a system for irrigation in greenhouses. The model is designed to capture water on the roofs of greenhouses and to store it for the irrigation of plants cultivated inside the greenhouse. COLPOS 5 demonstrates the possibility of successfully using a larger rainwater catch system in a variety of ecological and atmospheric conditions, even those that appear to be inadequate for irrigation. This model has a capacity of 2,000 cubic meters. The total estimated cost for the project is $18,000 USD.[25]
[pic]
COLPOS 5 diagram[26]
COLPOS 3: RAINWATER HARVESTING ON A COMMUNITY LEVEL
COLPOS 3 is particularly noteworthy due to its extensive and innovative design. This system is a purification plant and is intended to supply a community with sufficient potable water. In addition to capturing, conducting and storing rainwater, the plant purifies, fortifies and bottles the water. The bottled water from the plant is immediately ready for commercial sale. Currently, the model plant that was constructed on the COLPOS campus in 2004 is successfully distributing and selling bottled rainwater under the brand name “Lluviatl”. This brand name is a combination of the Spanish and Nahuatl (the indigenous language of Mexico) words for “rain”. The bottled rainwater, which comes in sizes of half liter, liter, and 19-liter (five-gallon) jugs, is sold in various locations throughout the city of Texcoco and is also used on the college’s own campus as the main source of drinking water. Water coolers with 19-liter jugs of purified rainwater are present in every academic building. Purified rainwater is also used and sold in the college’s cafeteria. The cistern’s capacity is 2,000 cubic meters and is meant to meet the daily requirements of up to 2,300 people.[27]
The basic components of COLPOS 3 are similar to the other previously described systems, the major difference being that the purification plant is made on a much larger scale. The collection process begins when rainwater falls to large rounded roofs that serve as the catchment area. The size of the catchment area is based on a formula designed by the CIDECALLI engineering team and is dependent upon the demand and availability of water. From the catchment area, the water is conducted through a large pipe into a storage area that is 2,000 cubic meters in size. This area is lined with a double layer of an impermeable material called geomembrane. The water is sent into the geomembrane so that the storage area fills while maintaining a cover over the top of the water. [28] The effect is similar to a giant water balloon filling up inside of an empty swimming pool.
The rainwater is then pumped out of the storage system by a hydro-pneumatic pump and passed through both a “Speedy” filter and a carbon active filter. Having passed through these preliminary filters, the water moves into the purification plant to undergo more intensive treatments. The first treatment is a series of three micro-polishers that are 20, 10 and 5 microns in size. These filters eliminate all visible impurities in the water.[29]
After passing through the micro-polishers, the water is transferred to a tank to be sterilized. Upon arrival at this tank, the rainwater is nearly potable, however, it is treated with ultraviolet (UV) light and ozone to guarantee that the water is sufficiently purified and fit for human consumption.[30] The UV rays function as a germicide and work to destroy germs, viruses, algae and spores. These living organisms are completely wiped out after their contact with UV rays, which means the water leaves this treatment free of living organisms.
The next treatment uses ozone to destroy microorganisms. Ozone works to rupture the cellular membrane of molecules. It disperses and destroys the cellular cytoplasm in the water in order to allow for reactivation. Ozone uses oxidation to eliminate the unhealthy elements in the water, including bacteria and metals.[31] Once purified, the water is packaged into previously-sterilized bottles and jugs, and is sealed and labeled, making it ready for sale.[32] Lastly, the purification plant must include a monitoring program for every stage of water production in order to guarantee superior quality.[33]
The purification process is of utmost importance to CIDECALLI and its rainfall harvesting models. Understanding the physical, chemical and biological properties of water in order to recognize how it becomes contaminated is integral in the design and construction of these rainwater harvesting systems. During training seminars, trainees are required to attend water quality lectures on topics ranging from the negative health effects of waterborne illnesses to the legal framework regarding purified and potable water.[34] This focus on purification and water quality is meant to ensure that the participants for these new rainwater harvesting projects leave with a real and lasting understanding of the importance of water quality. Consequently, these systems can have a lasting impact on the targeted communities
[pic]
COLPOS 3 diagram[35]
The economic valuation of COLPOS 3 demonstrates both its potential as a sound business model as well and as a stable source of clean and healthy water for marginalized communities. The initial investment per capita is $40-50 USD. The upfront investment for the purification plant is $1,235,574.02 MXP (approximately $112,575 USD).[36] This sum includes all machinery, plans, labor and taxes and is based on current costs in Mexico. The production cost of one 19-liter jug of purified rainwater is approximately $0.40 USD. The following projections are based on a gradual increase in plant production as demand increases over the first few years of operation. More specifically, the operating capacities are modeled after the real-life example of the plant constructed on the COLPOS campus. Operating at 85% capacity in its first year, the plant would produce 176,800 19-liter jugs of water and expect a return of $1,980,160.00 MXP. This forecast is based on an annual production rate of 680 jugs each day for 312 days. Operating at 90% capacity in the second year, the plant would produce 224,640 jugs and expect a return of $2,515,968.00 MXP. This forecast is based on an annual production rate of 720 jugs each day for 312 days. Operating at 95% capacity in the third year, the plant would produce 237,120 jugs and expect a return of $2,655,744.00 MXP. This forecast is based on an annual production rate of 760 jugs each day for 312 days.[37]
These forecasts demonstrate that the COLPOS 3 has the ability to be a profitable enterprise. They also suggest that the construction of a plant carries minimal economic risks. According to an economic valuation created by Professor of Agricultural Economics Plutarco Sánchez Velázquez the purification plant can break even fairly quickly. Within the first year of operation, the plant must operate at only 24.64% of its total capacity (meaning it would produce 43,555 jugs) in order to cover its operation costs. This percentage would decline over time and within 5 years the plant would need to operate at only 20.51% of its total capacity in order to break even.[38]
The COLPOS 3 purification plant appears to be a promising innovation and holds immense potential for sustainable investment enterprises around the world. CIDECALLI hopes that through the implementation of these prototypes, real progress in combating Mexico’s water woes can be achieved. The center is therefore working on expanding the use of these prototypes in rural and marginalized communities throughout Mexico.
MAZAHUA
Arguably CIDECALLI’s most groundbreaking project to date is the work completed in San Felipe del Progreso. This town is in the Mazahua zone, an indigenous region situated in the northeastern part of the State of Mexico and in a small area in the West of the State of Michoacan. The Mazahua people live in deep poverty without access to water and other basic necessities, making the region one of the most underprivileged and marginalized in Mexico. CIDECALLI worked with the Foundation Pro Zona Mazahua to construct a $1.5 million MXP (approximately $150,000 USD) rainwater harvesting project designed to benefit the 6,000 inhabitants of the Mazahua community of San Felipe del Progreso, Estado de México. The project is based on the COLPOS 3 prototype and has the capacity to supply 3.5 million liters of purified water each year.[39]
The real world implications of this prototype are extremely significant. The captured rainwater is purified in order to avoid the gastrointestinal diseases that tend to run rampant in rural communities with limited access to water treatment methods. Dr. Manuel Anaya Garduño points out that in various rural communities throughout Mexico rainwater harvesting is already used, but that the water is only treated by a simple boiling process. This treatment will kill some bacteria but will not eliminate organic and inorganic solids from the water.[40] The plant has been successful in its aim to provide clean water to the community and, some speculate, has the potential to be an additional source of income for the community. Community and project leaders even developed the brand name “Mazagua” for rainwater purified and bottled at the Mazahua plant.[41] CIDECALLI recently received special recognition from the Patronato Pro Zona Mazahua, A.C. 1997-2007 for ten years of working towards elevating the quality of life in Mazahua communities.
IMPACT ON RURAL DEVELOPMENT
The Mazahua example offers evidence of the positive impacts this type of rainwater harvesting project can have on a community. In his book, La Purificación Tepetitla: Agua Potable y Cambio Social en el Somontano, Michael Ennis-McMillan writes that recent government health programs have emphasized access to potable water as an important social and political goal. Unfortunately, these programs have adopted urban models and free market mechanisms of water distribution that have caused many disadvantages for rural populations of lesser economic means. These programs tend to ignore the existing practices and infrastructure in the target communities as well as systems for resource management. Ennis-McMillan argues that successful government programs are those that work within the community at the local level.[42]
It is precisely this argument that makes the CIDECALLI prototypes compelling. Research co in rural Mexico shows that many communities are already using rainwater harvesting techniques, and have been for nearly 100 years. Many communities have rudimentary systems in place to capture water, and the people in these communities demonstrate a positive attitude toward the use of rainwater for domestic purposes.[43] However, as with rainwater harvesting systems in other parts of the world, those in place in Mexico fall short of obtaining water quality high enough to be acceptable for daily human consumption.[44] For this reason, the CIDECALLI prototypes have the potential to be highly successful in solving water scarcity issues throughout Mexico. They utilize the existing acceptance and understanding of rainwater harvesting among community members to improve and expand rainwater catch systems in rural areas. This combination should be considered by public officials as a real and promising policy option for positive change in Mexico.
THE FUTURE
The success of CIDECALLI’s projects has spurred a rapid growth in the center’s scope. The center has already received more than 3,000 visitors in the two and a half years that it has been open to the public. These visitors leave glowing commentaries about both their visit to the center and the CIDECALLI prototypes. In order to expand the implementation of these systems, Dr. Manual Anaya Garduño, the director of CIDECALLI, has teamed with Dr. Albert Frost of Recycling Planet to create Akuavit – a private enterprise with the goal of spreading the development of rainwater harvesting projects throughout Latin America and the Caribbean Islands. Akuavit has planned 200 new projects to be implemented in the coming years in the Mexican State of Nuevo Leon, 300 projects in the State of Sinaloa, and 1,300 to be realized in the States of Chiapas, Guerrero, Oaxaca, Puebla, and Veracruz. The projects will be designed and implemented by hundreds of Mexican students and engineers hailing from top universities and research institutions. Akuavit is working on securing funding for these projects through municipalities and philanthropic organizations in Mexico and abroad.
Furthermore, the University for International Cooperation has contacted CIDECALLI and the two organizations are currently working together to develop a virtual education plan to be used throughout all of Latin America and the Caribbean. The education plan would be an online workshop on the design and construction of the CIDECALLI prototypes. The center has also made contact with the Center for Water in Arid Zones in Latin America and the Caribbean (CAZALAC) and through this organization is working with community leaders in Nicaragua, Chile, Panama, and Costa Rica who are looking to construct prototypes for rainwater harvesting in their own countries.
The success of the CIDECALLI prototypes in the face of growing worldwide water problems offers hope for the future. The unique combination of ancient resource management techniques and technological innovation give these projects the potential for significant impacts in the sustainable development of rural communities around the globe.
-----------------------
[1] Colegio de Posgraduados. (2007). Centro Internacional de Demonstración y Capacitación en Aprovechamiento del Agua de Lluvia (CIDECALLI). [Brochure]. Manuel Anaya Garduño: Author.
[2] Joint Water Monitoring Programme for Water Supply and Sanitation. “Water Supply Data at Global Level.” World Health Organization. United Nations Children’s Fund. 2006. . 07 Feb 2008.
[3] Colegio de Posgraduados en Ciencias Agrícolas (2007). III Diplomado Internacional “Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico” Manual del Participante (Con base en la Norma Técnica de Competencia Laboral. p. 15-25.
[4] Texas Water Development Board (2005). The Texas Manual on Rainwater Harvesting. Third Edition. Austin, Texas. Hari J. Krishna, P.E. p. 1.
[5] Colegio de Posgraduados. (2007). El Colegio de Posgraduados Trabaja con México. [Brochure]. Manuel Anaya Garduño: Author.
[6] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. (2007). “Diseño de Sistemas de Captación del Agua de Lluvia (SCALL).” [Powerpoint presentation]. José Juan Martínez: Author.
[7] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. [Personal observation]. 29 October 2007.
[8] Suárez Dueñas, José María. Personal Interview. 7 February 2008.
[9] Anaya Garduño, Manuel. “Rainwater Catchment Systems for Marginal Communities.” IV World Water Forum. Centro Internacional de Demonstración y Capacitación en Aprovechamiento del Agua de Lluvia. March 2006.
[10] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. [Personal observation]. 28 October 2007.
[11] Colegio de Posgraduados en Ciencias Agrícolas (2007). III Diplomado Internacional “Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico” Manual del Participante (Con base en la Norma Técnica de Competencia Laboral. p. 78
[12] Colegio de Posgraduados en Ciencias Agrícolas (2007). III Diplomado Internacional “Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico” Manual del Participante (Con base en la Norma Técnica de Competencia Laboral. p. 78.
[13] Texas Water Development Board (2005). The Texas Manual on Rainwater Harvesting. Third Edition. Austin, Texas. Hari J. Krishna, P.E. p. 6.
[14] Ibid.
[15] Colegio de Posgraduados en Ciencias Agrícolas (2007). III Diplomado Internacional “Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico” Manual del Participante (Con base en la Norma Técnica de Competencia Laboral. p. 82.
[16] Colegio de Posgraduados en Ciencias Agrícolas (2007). III Diplomado Internacional “Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico” Manual del Participante (Con base en la Norma Técnica de Competencia Laboral. p. 82.
[17] Texas Water Development Board (2005). The Texas Manual on Rainwater Harvesting. Third Edition. Austin, Texas. Hari J. Krishna, P.E. p. 10.
[18] Texas Water Development Board (2005). The Texas Manual on Rainwater Harvesting. Third Edition. Austin, Texas. Hari J. Krishna, P.E. p. 10.
[19] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. (2007). “Sistemas de Captación y Aprovechamiento del Agua de Lluvia.” [Powerpoint presentation]. Manuel Anaya Garduño: Author.
[20] Ibid.
[21] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. (2007). “Sistemas de Captación y Aprovechamiento del Agua de Lluvia.” [Powerpoint presentation]. Manuel Anaya Garduño: Author.
[22] Ibid.
[23] Email correspondence with Dr. Manuel Anaya Garduño. 2 April 2008.
[24] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. (2007). “Sistemas de Captación y Aprovechamiento del Agua de Lluvia.” [Powerpoint presentation]. Manuel Anaya Garduño: Author.
[25] Ibid.
[26] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. (2007). “Sistemas de Captación y Aprovechamiento del Agua de Lluvia.” [Powerpoint presentation]. Manuel Anaya Garduño: Author.
[27] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. [Personal observation]. 24 October 2007.
[28] Ibid.
[29] Ibid.
[30] Cesaro, Javier Salinas. “Desarrollan proyecto para purificar y envasar la lluvia para uso humano.” La Jornada. 12 April 2005. .
[31] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. (2007). “Sistemas de Captación y Aprovechamiento del Agua de Lluvia.” [Powerpoint presentation]. Manuel Anaya Garduño: Author.
[32] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. [Personal observation]. 28 October 2007.
[33] Colegio de Posgraduados en Ciencias Agrícolas (2007). III Diplomado Internacional “Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico” Manual del Participante (Con base en la Norma Técnica de Competencia Laboral. Chapter 7.
[34] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. [Personal observation]. 28 October 2007.
[35] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. (2007). “Sistemas de Captación y Aprovechamiento del Agua de Lluvia.” [Powerpoint presentation]. Manuel Anaya Garduño: Author.
[36] III Diplomado Internacional Sistemas de Captación y Aprovechamiento del Agua de Lluvia para Consumo Humano y Uso Doméstico. (2007). “Análisis Económico y Financiero el Proyecto: Ejemplo Purificadora.” [Powerpoint/Excel presentation]. Plutarco Sánchez Velázquez: Author.
X- Currency Calculator. 25 November 2007. .
[37] Ibid.
[38] The equilibrium point percentages were calculated using the following equation: Fixed [Costs / (Total Sales – Variable Costs)] X 100.
[39] Fondo para la Comunicación y la Educación Ambiental, A.C. “Agua de lluvia para vivir y producir.” 31 January 2008. .
[40] Fondo para la Comunicación y la Educación Ambiental, A.C. “Agua de lluvia para vivir y producir.” 31 January 2008. .
[41] Teorema Ambiental. “Cosechan mazahuas agua de lluvia.” 01 Feb 2006. Number 55. 03 April 2008. .
[42] Ennis-McMillan, Michael C. La Purificación Tepetitla: Agua Potable y Cambio Social en el Somontano. Trans. Carmen Viqueira Andrea Ruiz. Ciudad de México: Universidad Iberoamericana A.C, 2001. p. 26.
[43] Torres, Marisol Pineda. 2007. Manejo de Agua para Uso Doméstico en Jumiltepec, Municipio de Ocuituco, Estado de Morelos. Master’s thesis, Colegio de Posgraduados, Institución de Enseñanza e Investigación en Ciencias Agrícolas. p. 66-69.
[44] Ibid. p. 92.
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