Clean water - we need it, other animals need it, plants too! In fact, every living thing needs access to clean water. But water can pick up all kinds of potentially harmful stuff during its never-ending journey through the water cycle - nitrates, phosphates, dog poop, heavy metals - how does all this stuff get into our water in the first place? And how can we know when it does? And what does it mean for the health of our environment, and us!? For our water series this summer we’ll be tackling these questions along with some of your questions, like “Why does water expand when it’s cold when other things don’t?” and “Why does water stick to things?” It’s going to be a splash!

To help steer our aquatic voyage we’ve brought an award-winning kid scientist on board! 12-year old Gitanjali Rao won the 2017 Discovery Education 3M Young Scientist Challenge for an amazing idea she had to help people learn what’s in their water and -- spoiler alert -- it involves carbon nanotubes! We talk with Gitanjali about what it’s like to compete in a science competition, and learn about what inspired her to create her device - the Flint water crisis. But first things first - the water cycle.

Our planet is home to 326 million cubic miles of water. It’s kinda hard to wrap your head around a number that big, so let’s use our imagination. Shrink the earth down to the size of a basketball. Now, imagine that all the water in the oceans, ice caps, lakes, streams, rivers, glaciers, can be sucked up into a single blob. This blob would be about the size of a ping pong ball. Almost all of that ping pong ball would be salt water. Freshwater makes up less than 3% of the ball, and most of that freshwater is locked up in ice. This means that only 1% of all the water on Earth is available for us (along with all other living things) to use! That 1% of water is also very vulnerable to getting polluted as it moves through the water cycle. The picture below illustrates the idea in a different way.

How much water is on earth?
The Earth stripped of its water (left). All of the Earth's ocean water (middle) and freshwater (super small speck on the right)
David Gallo/WHOI

Earth’s water is in constant motion, but much of that motion is too slow for us to see. Despite its sluggishness, the flow of water through the water cycle is the largest movement of any substance on earth! Larger than the migration of wildebeests on the African Savannah! Or the formation of the Himalayan mountains! The engine of this movement is the sun, which warms the oceans and powers plant photosynthesis. Water vapor from surface water and plants evaporates and drifts up into the atmosphere, where it collects in clouds, and falls back down to earth in the form of rain, snow, sleet or hail. From there it can fall back into the ocean, enter lakes and streams, seep into the ground and be stored in aquifers, or become frozen into a glacier. Roughly every 3,000 years, a volume of water that could fill all the oceans of the world completes this cycle!

The water cycle
The water cycle

This leaves lots of opportunities for human activities like industrial production, agriculture, even keeping pets like cats and dogs, to introduce pollutants into the water cycle. Fertilizer runoff from ponds can disrupt the balance of nutrients in lakes and streams; chemical waste from factories can harm fish and plant life; and sometimes, if our drinking water isn’t treated properly heavy metals like lead can leach from the pipes that carry water into our homes and cause health problems.

This is what happened in Flint, Michigan in 2014. In this episode we learn why the vast majority of our drinking water does not have lead in it, and what caused Flint’s water to become polluted with lead. We hear from the Banks family, whose lives were turned upside-down from the crisis, and Marc Edwards, a Virginia Tech professor citizens in Flint called on to prove there was a problem.

The Banks Family
The Banks Family: Charles and Dana, with kids Alana (14), Olivia (13), and Troy (9).
Barbara Lucas

Gitanjali Rao, our co-host, was following the Flint crisis on the news, and put her super science skills to work in finding a solution. It can take a long time for people to learn whether or not their water has lead in it with current testing methods. You’ve figure out how to take the sample correctly, send it into a lab, and wait for the results - it can take weeks! Gitanjali devised a device she later named “Tethys”, after the Greek goddess of fresh water. Tethys uses carbon nanotube technology to detect how much lead is in your water, and transmits this information to your smartphone in less than a minute!

Gitanjali with holding her Tethys device
Gitanjali Rao at the Discovery Education 3M Young Scientist Challenge. She's holding her award-winning device, Tethys, which quickly tests for lead levels in drinking water.
Bharathi Rao

Learn more about Gitanjali’s invention here.

Stay tuned for more episodes in our water series. In our next episode we’ll talk all about how weird water is, and how it’s weirdness makes it special, and worth protecting. Plus, we’ll fill you in on how you can team up with Brains On and Earth Echo International to learn what’s in your water!

In the meantime, interested in learning if your home is connected to the water main by a lead service line? Check out this link.

Brains On’s water series is powered by the Water Main, a new initiative from American Public Media focused on connecting people to their water resources. Find out more at