"And," Trusler added, "there are all of these downpipes that are part of that picture that no one is really considering." [Image Gallery: A Look at Pompeii's Toilets]
So Trusler decided to conduct a plumbing survey of sorts, mapping latrine and downpipe locations around the city. One residential district, known to archaeologists as Region 6, does indeed have toilets on the ground story of almost every home, she said. But other blocks have few toilets. In total, 43 percent of homes in the city had latrines on the ground floor, Trusler found.
Downpipes provide the other half of that picture. These vertical, usually terracotta pipes are concentrated in the oldest part of the city, where there were many workshops and small businesses crammed into close quarters. A total of 286 pipes run down the walls of these buildings, leading to the mostly lost second floors. In 23 cases, however, the second story remains, and the same types of pipes lead to latrines.
In addition, Trusler said, unpublished research on scrapings from the insides of the pipes revealed fecal material and traces of intestinal parasites, good signs of a toilet.