Why use a normal water filter when you can get your water from a mini-rain forest? That’s exactly what Pratik Ghosh built. His filtration system is called Drop by Drop which is a fitting name because this system generates a 3/4 cup of clean water in one day. First, the plants’ roots absorb the water. There, it evaporates and is then collected for drinking. Ghosh claims that this process filters out nitrates, heavy metals, chlorine, and bacteria. Ghosh hopes that the system can be scaled up and wants to utilize unused rooftop space.