The tech behind smart cities

Stormwater runoff is one of the biggest pollutants around the world.

Roughly 10 trillion gallons of stormwater travel through sewage systems and roads -- picking up bacteria and chemicals along the way -- before funneling into surrounding bodies of water.

OptiRTC, based in based in Brookline, Mass., has developed technology to help mitigate this. A valve and sensor are added to existing rainwater collection tanks, which indicate how full the tanks are. Real-time weather monitoring alerts the tanks to automatically empty before a storm. (The collected rainwater is often used for landscape irrigation, as in the case of Washington D.C.'s Environmental Protection Agency building, which uses OptiRTC technology.)

OptiRTC brings "control to markets that have not historically had any control," said Marcus Quigley, principal at Geosyntec (the parent company of OptiRTC).