Thousands of students returning to the Rochester Institute of Technology in New York this month are being asked to wear masks in public, register their health status online each day and electronically log classroom visits for contact tracing if a coronavirus outbreak occurs. But the most novel effort at the school to measure and limit virus spread will require little effort and come quite naturally.

Students need only use the bathroom.

At more than 15 dormitories and on-campus apartment buildings, sewage is being tested twice weekly for genetic evidence of virus shed in feces. This provides a kind of early-warning system of an outbreak, limiting the need to test every student for Covid-19. If the disease is found in sewage, individual tests can be administered to identify the source.