Tackling Lead Contamination in Water


by Gitanjali Rao


How many times per day does water pass your lips? Unless you are severely dehydrated, your answer should be fairly high. Have you ever once considered how safe that water actually is?


Water contamination may sound quite alien to us in first world countries, but unfortunately that is the reality in many places. Mercury, arsenic, lead and cadmium are also some of the top metallic contaminants of water. Lead contamination, in particular, is very common around the world, with 33% of water samples in the top 26 Indian cities containing harmful traces of lead. 31% of these failed to meet the World Health Organisation’s standards of less than 10ppb (parts per billion) and 2% failed by Indian standards of 50-100ppb.


Lead manages to find its way into our water supply in numerous ways, including corrosion of old lead pipes, solders in pipe joints, low quality PVC pipes and even brass faucets. These are most common in older buildings, like old build houses and schools, so contamination is more common than you may think!


When lead gets into water, it can be harmful due to the lingering effects it has on the human body. A child can experience birth defects and abnormal growth with high lead levels in their body. Health effects of lead in water can range anywhere between headaches and nausea to seizures and in serious cases, death.


I first heard these worrying facts 3 years ago, along with the water crisis in Flint, Michigan. I found it hard to accept that there was a place where children my age were having to drink water that was essentially poison. This was leaving them with lifelong damage to their mental capacity, vital organs and even normal growth!


I decided I couldn’t stand by and watch, so to help to solve this problem I created a quick and accurate tool to detect lead contamination levels in water. It is built on the idea of carbon nanotube technology, which is radically different from the current approaches on the market.

The resultant tool was names ‘Tethys’, after the Greek goddess of fresh water. It consists of 3 components:​

  1. A core device, with a microcontroller, that includes in-built Bluetooth and a battery power source

  2. A disposable cartridge

  3. A smartphone that connects via Bluetooth to displays results.

The disposable sensor cartridge includes carbon nanotubes with chloride atoms.  When the cartridge is dipped into lead-contaminated water, the lead sticks to the chloride ions, forming “Lead Chloride” molecules. Think of these molecules as speed bumps on the bottom of the carbon nanotube. The more molecules there are, the slower the current, going through the nanotube, will move. The amount of resistance is measured using a microcontroller which has built-in Bluetooth. This then connects to a smartphone app, via Bluetooth, to display the whether the water is safe, slightly contaminated, or critical.


One day, I aim to have Tethys as a must-have household item so that water can be tested routinely. I hope people will start to take water quality as seriously as doctor or dentist appointments, since what we drink directly correlates with health.


Each and every one of us has the right to know what is in our water and have access to clean drinking water. We should never have to see another Flint Water Crisis again and I hope Tethys can help with that and change our world for the better. Remember that clear water doesn’t always mean clean!

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