More than 70 million people in Bangladesh drink polluted water every day and one in five water wells have dangerous levels of arsenic, a metalloid that leads to high rates of infant mortality and cancer. Photo: Stephen Goodwin Honan U.S. Navy officer Stephen Goodwin Honan has developed a plant-based solution that can remove arsenic from drinking water using $10 worth of ferns. Photo: Stephen Goodwin Honan If the project continues to scale, Honan hopes the arsenic sequestered in the leaves of the plants can be extracted and sold to manufacturers. The arsenic in the plants is worth about $85 and would represent a life-changing income source to people who subsist on less than a dollar a day. Photo: Stephen Goodwin Honan The problem isn't confined just to the developing world. "Over 2 million Americans are unknowingly drinking arsenic-contaminated groundwater from their private wells," says Honan. "Raising awareness in the U.S. can help save lives domestically, and will bolster our cause abroad." Photo: Stephen Goodwin Honan There are two traditional ways to reduce arsenic in water supplies. Create a membrane and push water through it to screen out the impurities, creating toxic sludge in the process. Or, use chemicals to neutralize the heavy metals. Honan decided to solve the problem with ferns and a process called phytoremediation that uses plants to rapidly accumulate dangerous chemicals without the use of electricity and at a very low cost. Photo: Stephen Goodwin Honan Honan trained villagers to test drinking water well and set up purification systems for their neighbors, allowing them to make extra money in the process. Photo: Stephen Goodwin Honan

3.4 million people, almost the entire population of Los Angeles, die from water-related diseases every year. One of the chief polluters is arsenic, a metalloid that is vital to the fabrication of semiconductors, and by extension, everything from solar panels to iPads. Unfortunately, a single drop of liquified arsenic could render an entire swimming pool's worth of water unsafe for human consumption. Over time, that amount would lead to increased infant mortality and cancer.

Well-meaning designers have tried to solve the clean water problem with design thinking in the past. Their solutions are often clever and beautiful, but are often too expensive to deploy at scale and end up winning design awards without solving the problem at hand.

Stephen Goodwin Honan, a 24-year-old U.S. Navy officer, decided to address the problem using ferns. He discovered a species called Pteris cretica that could thrive near arsenic mines. He set up a hydroponic rig in his basement to see if the plant would leach arsenic from the water. After a rough start where his lack of a green thumb nearly killed plants that can subsist on one of the world's most toxic carcinogens, the experiment succeeded.

Honan's system, dubbed Clean Water, isn't pretty in any conventional sense, but the elegance of the design can't be overstated. No specialized equipment is needed—any watertight bin filled with $10 dollars worth of starter plants and placed on a makeshift bamboo table will work. Tainted water is poured into the vessel and the plants immediately start absorbing the toxin through their roots, cleaning a half-gallon of arsenic tainted water every minute. Newly filtered water is tested to ensure the plants have done their job and is then poured into another vessel for household use. After many cycles, the plants become saturated with arsenic, are harvested, and taken to a lab where they're transformed into a substance that looks a bit like green Jell-O. This gross gelatin is heated releasing arsenic vapor into an enclosed chamber here it's captured and sold to manufacturers, leaving harmless biomass behind.

"Phytoremediation, using plants to rapidly extract toxins from the environment, has existed for decades, but few plants have been adapted for small scale drinking water filters," says Honan. "Most people in western countries are unwilling to trade-off long remediation periods for lower cost filtration systems; however, in developing countries, such as Bangladesh, this trade-off proves critical for technology adoption."

Proof of concept in hand, Honan took his plants and blue plastic bins to Bangladesh, the most densely populated country in the world, where more than 70 million people are essentially forced to drink poison on a daily basis. His process worked in the field, but there were surprising side effects. As demand for testing and filtration services exploded, Honan started training villagers to analyze water sources and set up new purification systems, allowing them to pocket some extra money in the process.

Honan's smart design choices could help Clean Water succeed where so many projects have failed before it. Training is minimal and leverages skills the agrarian population already has in spades. The arsenic captured in a single system's plants is worth about $85 to manufacturers, a life changing sum in a country where most of the citizens subsist on just a dollar a day. Honan has managed to turn a destructive chemical into a potentially lucrative crop that could lead to a thriving social enterprise.

Now the challenge is effectively handling the poisonous plants come harvest time. "We are currently working to upcycle or recycle all of the components of the filter: arsenic for semiconductors, green biomass for plant fertilizers, and plastic containers for future filters," says Honan. "In order to scale our project, we are looking to partner with a semiconductor manufacturer and deliver the world's first socially responsible arsenic."