While it’s often overlooked, stormwater has great potential to solve the problem of strained water supplies in urban areas. One of the main reasons why this resource has gone mostly untapped is because stormwater picks up toxic chemicals as it runs through streets and gutters.

Now that may no longer be a problem thanks to an innovation developed by scientists at UC Berkeley. The engineers have developed mineral-coated sand that can not only soak up organic contaminants like pesticides in stormwater but also remove harmful metals during filtration.

Cities often discard stormwater as pollution because it picks up contamination like lead particles left behind from decades of leaded gasoline emissions or pesticides from lawns. Exposure to these chemicals is associated with slow neurological development in children and some types of cancer.

However, researchers say that their coated sand material could be installed in rain gardens in places like parking lots where stormwater can be collected and cleaned.

To make the filtration media, the scientists coated sand particles with manganese oxide, a naturally-occurring nontoxic mineral commonly found in soil. They estimate that this material could remove metals from stormwater for over a decade in a typical infiltration system, which would convey runoff into underground aquifers.

The innovative material could turn pollution into a solution for stressed water supplies, particularly in parched cities that pay to import water.