DEVON, ENGLAND—In the medieval period, fresh drinking water was carried into the city of Exeter through a network of tunnels, according to Mark Stoyle of the University of Southampton. He examined historic documents that record the plumbers’ activities and list the supplies that they needed, including lead, candles, and lanterns. “People from all social backgrounds relied on the system to provide their drinking water, so it was vital to keep it running smoothly. The city retained a plumber to carry out regular maintenance and he, in turn, hired in a team of workers to help with specific jobs,” Stoyle told Science Daily. The brick-lined tunnels were constructed to protect the lead pipes that carried the water, and to provide the plumbers with easy access to them. “Imagine if today there was no more digging up the roads to mend a water main!” he said.