A 12-Year-Old Girl’s Invention Can Immediately Detect Water Contamination

Paroma Soni
5 min readJun 19, 2020


Even though India is rich in natural resources, we are a country with a massive overpopulation and pollution problem. For decades, environmental protection has been brushed under the carpet against a slew of so many other issues that seem more imminent. But the dangers of climate change disproportionately affect the country’s most vulnerable — particularly millions of people who do not have access to one of the most basic human rights: clean drinking water.

In fact, water contamination is a massive issue in India. Factories, agricultural industries, and landfills have discarded huge amounts of toxic waste into our water supply, rivers and oceans, and groundwater wells. A Times of India study found groundwater contamination in over 50% of national districts — that is, more than half the country has water containing arsenic, pesticides, fertilizers and metallic compounds like lead nitrates. These lead to hundreds of birth defects, health problems, and wildlife destruction.

Something similar happened a few years ago in Flint, Michigan when the city’s water supply was found to contain large amounts of lead due to insufficient treatment. The resulting scandal led to increased awareness of water contamination, and inspired Gitanjali Rao, a 12-year-old Indian American, to take up the fight for change.

She invented a quick, low-cost test to detect lead contamination in water using carbon nanotubes. Her portable invention, named Tethys after the Greek goddess of freshwater, includes a mobile sensor and app that gives an accurate and instantaneous analysis of the sample.

She spoke the 10th edition of the TEDxGateway Conference in Mumbai about this and more. I had a lovely chat with Gitanjali about her fascinating talk (lightly edited for length and clarity) and some insight into her strong vision and ambitious plans.

PS: What’s the first thing that got you so excited about science and the environment?

GR: When I was seven years old, I started learning about water contamination and effects of climate change. Almost at the same time I started to get exposed to amazing new technologies like nanomaterials and genetic engineering. That’s when I knew I could use science to help solve these big problems.

PS: What inspires you and keeps you this passionate at such a young age?

GR: When I hear about a problem online or on the news, I start thinking of ways that I can help. I start to create something that can reduce the pain and suffering in this world. There are times I hit roadblocks, which I feel can never be overcome, but I think about the people living these realities every day. I’m motivated by imagining that any solution I find will help others improve their lives, even a little bit. Especially when I hear about a new technological development, I become excited and start to think about all the possible applications I could discover. I firmly believe that science and technology can be a huge catalyst for social change.

PS: What do you think is the biggest threat to our planet today?

GR: It’s a combination of issues related to the contamination of natural resources and climate change.

PS: What inspired you to create Tethys? What was your favourite part of the process and what were some big challenges you had to overcome?

GR: I was originally inspired by the Flint Water Crisis, which I saw on the news one night during dinner, about three years ago. I continued to research and follow it for the next couple of years. Then I saw my parents testing for lead in that water and that is pretty much what sparked the idea: realising that using test strips isn’t the most accurate or timely way to test for contamination. Also, it is too expensive for everybody to afford them. I really wanted to do something to change this not only for my parents but also for the residents of Flint and places like Flint around the world.

My favourite part of the process, hands down, is watching a simple and conceptual idea slowly come together with wired processors, 3D Printed Cases, batteries, and CNTs! When I had originally thought of this idea, I was unsure of how to bring this all together. I pushed through a summer of obstacles and roadblocks like not being able to find a lab to do all my tests. But it all eventually started to become real. I must keep testing still, especially for false positives, as well as tune the sensors using other chemical combinations, but I feel confident about getting some early prototypes out in the field.

PS: What impact do you hope Tethys will have in the future? How would you like to see technology like this develop? HG: How can we get other young people to care about these issues and actively change their behaviour towards a solution?

GR: After my testing, and developing a method for gathering data for analytics, I intend to partner with the US Environmental Protection Agency to crowdsource water quality data. The idea is to not only test local water sources but also to try and use the data from various sources to produce a heat map, that shows the contamination levels in a region in a single view. It can also help in developing prediction models of the spread in the future. Simultaneously I intend to create about 30–50 reproducible prototypes that can be used for field-testing starting with Flint.

GR: I am one of the many who are looking to make a positive impact on the environment. We’d like to show the world that, beyond the fun world of cool gadgets and social media channels, we can contribute to making the world a better place, by solving the problems of today and tomorrow. Our generation is growing up in a place where we’re facing and seeing problems that have never existed before such as global warming, space debris, contamination of natural resources, cyber-bullying, and more. We need to show that we have the power to make a difference.

I’m doing my part by speaking in forums, writing articles, and actively testing water samples. Together, we can make a difference.

Originally published at https://homegrown.co.in on November 29, 2018 by Paroma Soni



Paroma Soni

writer, videographer, editor — new to Medium! passionate about identity, film, culture, and politics. currently working at BuzzFeed. → www.paromasoni.com