Hawai'i-American Water Co. is conducting smoke testing of sewer lines through Nov. 15 in Haha'ione and Kamiloiki valleys, the company said.

The smoke testing is done to help the company identify breaks and defects in the sewer system. The company last did smoke testing of the sewer system in 2006.

The test uses non-toxic, non-staining smoke that has no odor, but is gray to white in color. Smoke rises to the surface through possible cracks, defects or illegal connections to the sewer system. Work will take place between 8 a.m. and 5 p.m. weekdays.

Residents should call 596-7790 with questions.