As the Mexican city of Lerma has become an industrial center with nearly 3 million residents, factory wastewater and local garbage have polluted the Lerma river - and thus local wells. Researcher Verónica Martínez Miranda developed a homemade filter for her well that combined eggshells with magnesium oxide and calcium hydroxide. It reduces heavy metals by 80% and fecal matter by 100%. Now she and her neighbor, Elvia Arias, fix wells for others through the H2O Lerma With Charm collective, using social media to collect the one to two tons of eggshells needed for each filter.

Read Full Story