City Department of Environmental Services crews will conduct "smoke testing" of the wastewater collection system in Wahiawa residential areas today through Friday as well as April 29 through May 2.

In the testing, crews blow smoke into sewer lines, examine whether any smoke escapes, and record its location. The department said the smoke is nontoxic, odorless and is not a fire or health hazard.

The testing helps crews locate broken pipes, illegal connections and other paths for runoff to enter the sewer system, the department said. Such runoff can overwhelm the system and cause sewage spills.

Crews will conduct the smoke-testing on the following streets: Glen Avenue, Glenview Place, Wonder View Place, Kanoelehua Place, Nahenahe Place, Royal Palm Drive, U'uku Street, Nichols Street, Turner Street, Clark Place, Eames Street, Kilea Place, Dole Road, Hakuone Street, Hakuone Place and Kinikohu Street.