Smoke-testing of the city's wastewater collection system will be conducted by the Department of Environmental Services in Wahiawa residential areas tomorrow through Friday, and again March 24-27.

The smoke-testing is part of the department's preventive maintenance program that tries to stop rainwater from entering the sewer system. Crews pump smoke into sewer lines, examine whether any smoke escapes and record the location. The smoke used is non-toxic, harmless and has minimal odor. The smoke is not a fire hazard and does not pose a health hazard to humans or pets.

Tests locate broken pipes, illegal connections, open cleanouts and other paths for runoffs that enter the sewer system. Runoff from heavy rain can overwhelm the sewer system and treatment plants, causing spills.

Areas set to be tested: California Avenue, Ihoiho Place, Rose Street, Rose Circle, Circle Drive, Hauola Avenue, Manua Street, Nanea Avenue, Makaweo Avenue, Loko Drive, Loko Place, 'Oliko Place, Kilau Place, and 'Iliwai Drive.