Developing countries, particularly in South Asia, are characterized by having a major portion of their population living in rural areas. The quality of drinking water in these areas, and especially rural schools in these countries, is very poor. Data suggests that not only is there a paucity of water but the drinking water available in schools has high coliform loading and contain high amount of dangerous chemicals such as arsenic and nitrates which can cause thyroid problems, cancer, skin and kidney diseases among many others.  

Drinking contaminated water with high coliform loading is hazardous and creates intestinal infections in children which results in their poor health because of diarrhea, typhoid, cholera, hepatitis A and E and other waterborne diseases.

Sustained intestinal infections in children also affects their mental health and contributes to the development of psychiatric disorders which can last lifelong.  Thus availability of good clean drinking water for school children is very important for their long term mental and physical health.  These issues are specially relevant to South Asian countries which are characterized by poverty and overall poor drinking water availability.

To alleviate drinking water woes for rural schools, a unique clean drinking water technology (CDWT) has been developed by  the Nimbkar Agricultural Research Institute (NARI), an NGO, in Phaltan, Maharashtra, India. The clean drinking water technology (CDWT) can provide 100-200 liters of clean water per day to about 200 children in rural schools.

Two schools, one in Nandal village and another in Adarki village of Phaltan Taluka have been selected for implementing this technology. The CDWT systems have been donated to both the schools by NARI, and they have been working satisfactorily for the last 4-5 months.         

Solar purification system

The system is based on the technology of harvesting rainwater and then cleaning it through unique solar purification system developed by NARI.  Usually rainwater runoff is used as grey water but this technology is probably the first to use it for drinking purposes.  Rainwater usually does not contain harmful chemicals like nitrates and arsenic and if present they are in trace amounts. Hence it is quite good for drinking purposes provided it is made potable via a suitable cleaning system.       

The rain water is collected from the school rooftop via suitably designed collection channels and filtered and stored in food grade plastic tanks. This water is then cleaned through appropriate filters and a solar thermal system (which runs without electricity) to provide clean drinking water for children.  The water storage capacity of the tanks is dictated by daily water usage, roof area and the yearly rainfall of the region.  

The technology evolved through R&D for the last 10-15 years where different solar water heating systems, various filter materials and strategies were tried to clean the water. 

The solar thermal system was also tested for a couple of years to collect the year-round data.  Thus even on a completely cloudy day the system is capable of destroying the coliforms when the stagnation water temperatures in solar system reaches more than 450C for 3 hours – long enough to inactivate the E. coli. Tests done in Phaltan show that in a year only for 3-5 days the system does not work since the water temperatures are below the threshold limit of 450C.

 The microbial E. coli count of drinking water from the system (regularly tested in NARI labs) is less than 20 MPN and much below the WHO standards. This shows that the system is working properly.

Hands-on education for children

The CDWT system has been in operation in both the schools for the last 4-5 months and the children are getting clean drinking water for the first time. The system has also been designed in modular form and can be operated by school children.

One of the main components of this technology is to teach the children about rainwater harvesting, solar energy and water testing using hands-on approach. This may help the rural school children to become interested in STEM (Science, Technology. Engineering and Mathematics) stream.

 Consequently teaching and instructional modules have been prepared in the local language for students so that they can learn about solar energy, water testing, rainwater harvesting methods, etc. These modules have been given to the teachers in the school so that they can instruct the students.              

Cost of the system

The major cost of the system (60% of the total cost) comes from the rainwater storage tanks.  Jal Jeevan Mission is a national initiative of Government of India for providing clean drinking water to every rural household and public institution, including schools and we feel that this cost can easily be defrayed by GOI for rural schools.  The life of the system is a minimum of 10 years.

Thus for 10-year life cycle the cost of water is Rs. 2.3/liter with 5 year loan repayment and with cost of tank defrayed by GOI it comes to Rs. 1.3/liter.  Though the cost of water is slightly high compared to existing systems, the beneficial effects on children’s health far outweigh the cost.    

Such a technology can be shared and spread to all rural schools of not just Maharashtra state, the rest of India, but other South Asian and African countries. 

(The writer, an IIT and US-educated Indian engineer,  a 2022 Padma Shri award winner, is the Director, Nimbkar Agricultural Research Institute, Phaltan, Maharashtra.  He can be reached at anilrajvanshi50@gmail.com/@anilraj24.bsky.social)