In many developing nations, particularly in South Asia, a significant portion of the population resides in rural areas. The availability of clean drinking water in these regions, especially in rural schools, remains a major concern. Studies indicate that not only is there a scarcity of water, but the drinking water that is available in schools often contains harmful contaminants. High levels of coliform bacteria and dangerous chemicals such as arsenic and nitrates have been detected, which pose serious health risks. Consumption of such contaminated water can lead to thyroid disorders, cancer, skin ailments, kidney diseases, and numerous other health complications.
Drinking water with excessive coliform bacteria is particularly hazardous for children, as it can cause severe intestinal infections. These infections can result in illnesses such as diarrhea, typhoid, cholera, hepatitis A and E, and other waterborne diseases. The consequences extend beyond physical health, as prolonged intestinal infections can also impact mental well-being. Research suggests that such infections in children can contribute to long-term psychiatric disorders, further emphasizing the importance of providing safe drinking water in schools. This issue is particularly relevant in South Asia, where poverty and inadequate access to clean drinking water are widespread.
Solar Water Purification System Installed by NARI
To address this critical problem, the Nimbkar Agricultural Research Institute (NARI), a non-governmental organization based in Phaltan, Maharashtra, India, has developed an innovative clean drinking water technology (CDWT). This system has the capacity to provide 100-200 liters of purified water daily, sufficient to meet the drinking water needs of approximately 200 students in rural schools.
Two schools, one in Nandal village and another in Adarki village, both located in Phaltan Taluka, have been selected for the implementation of this technology. The CDWT systems, donated by NARI, have been operational in these schools for the past four to five months, functioning efficiently to provide students with access to clean drinking water.
Rainwater Harvesting and Solar Purification
The core of this water purification system lies in its ability to harvest rainwater and purify it using a specialized solar-powered purification process developed by NARI. Typically, rainwater runoff is utilized as grey water for non-drinking purposes, but this technology is pioneering its use for drinking. Rainwater, in its natural state, does not contain harmful chemicals like nitrates and arsenic, and if these contaminants are present, they are usually found in trace amounts. With proper purification, rainwater can serve as a safe and reliable source of drinking water.
The system collects rainwater from school rooftops using specially designed channels. The water then passes through filtration units before being stored in food-grade plastic tanks. After storage, the water undergoes additional filtration and solar thermal purification, which operates without the need for electricity. The size of the storage tanks is determined based on daily water consumption, the available rooftop area, and the region’s annual rainfall levels.
The development of this technology has been an ongoing process, spanning 10 to 15 years of research and experimentation. Various solar water heating techniques, filter materials, and purification strategies were tested to ensure optimal water quality. The solar thermal purification system was extensively evaluated over several years to collect data on its efficiency throughout different seasons.
One of the key findings of these trials was that even on completely overcast days, the system remains effective in eliminating coliform bacteria. This is achieved by ensuring that the temperature of stagnant water in the solar purification unit exceeds 45°C for at least three hours, a threshold sufficient to inactivate harmful E. coli bacteria. Tests conducted in Phaltan indicate that the system fails to reach this temperature on only three to five days per year, demonstrating its reliability in most conditions.
Regular testing of the purified drinking water at NARI’s laboratories has shown that the microbial E. coli count remains below 20 MPN, which is well within the standards set by the World Health Organization (WHO). This consistent performance confirms that the system is effectively providing safe drinking water to students.
Educational Benefits for Students
Beyond providing clean water, the CDWT system is designed to be interactive and educational. Students in both participating schools have had access to clean drinking water for several months, marking a significant improvement in their daily lives. The system is modular and simple enough to be operated by schoolchildren, making it an excellent educational tool.
A key objective of this initiative is to teach students about the principles of rainwater harvesting, solar energy, and water quality testing through hands-on learning. This approach aims to foster an interest in STEM (Science, Technology, Engineering, and Mathematics) subjects among rural students, potentially inspiring them to pursue careers in these fields.
To facilitate this learning process, instructional materials have been developed in the local language. These materials cover topics such as solar energy utilization, water purification methods, and rainwater harvesting techniques. Teachers at the schools have been provided with these resources to integrate them into their lessons, ensuring that students gain valuable knowledge about sustainable water management.
Cost and Affordability of the System
One of the primary cost components of the CDWT system is the rainwater storage tanks, which account for approximately 60% of the total installation cost. The Indian government’s Jal Jeevan Mission, a national initiative aimed at providing clean drinking water to every rural household and public institution, including schools, could potentially cover this cost. If the government subsidizes the storage tanks, it would significantly enhance the affordability of this technology for rural schools.
The system is designed to have a lifespan of at least 10 years. Over this period, the cost of water production is estimated at Rs. 2.3 per liter, assuming a five-year loan repayment for the system. However, if the cost of the storage tanks is covered by the government, the cost of purified water reduces to Rs. 1.3 per liter. While this cost may be slightly higher than conventional water supply methods, the health benefits provided by this clean water system far outweigh the financial considerations.
By implementing this innovative solution, rural schools in India and other developing regions can address the persistent challenge of contaminated drinking water. The integration of solar-powered purification and rainwater harvesting not only ensures a sustainable water source but also promotes environmental awareness and scientific learning among students. With support from government initiatives and NGOs, such projects have the potential to significantly improve the health and educational outcomes for children in underprivileged communities.