Smoke rises out of a manhole near 13th and Delaware Streets as city crew member Mark Hegeman, left, and Matt Fishburn prepare to test another sewer line area. City crews were smoke testing sewer lines Thursday.

The saying, “Where there’s smoke, there’s fire” is not always true.

The Lawrence Department of Utilities conducted a smoke test Thursday, when crews blew smoke into sewer pipes to check for cracks and other defects. Crews monitored where smoke escaped from the pipes — areas that leaked smoke could leak water as well.

“This seemed like a fairly efficient way to narrow down the area,” said Jeannette Klamm, utilities program manager for the city. She thought it had been about 10 years since the last time the city conducted such a test.

The pipes filled with smoke are along Burroughs Creek Trail from 11th to 15th streets between Delaware Street and Haskell Avenue, an area where storm water enters the sewer system. City officials thought pipes in this area were likely to need some repair, which is why they conducted the test there.

Klamm said the next step will be to send a camera mounted on remote-controlled wheels to get a closer look at the areas that leaked smoke. The camera will send back pictures to determine whether there are indeed defects that need repair.

Crews began working at about 7 a.m. and completed monitoring the odorless, nontoxic smoke at 3:30 p.m. The tests had been scheduled to be continued today, but were completed a day early.