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Testing for Leaks

back to Collection System Maintenance Division


ENV crews use nontoxic smoke to locate leaks in our sewer lines. They will replace your caps, too.








Spill control teams respond to broken City sewer lines any time, night or day.

A smoke machine pumps a non-toxic liquid smoke into a manhole on the street. The smoke runs along the City sewer line to the centipede-like legs of private plumbing lines. If all is well, smoke will spiral out of small vents on house roofs. Smoke coming from a rain gutter or downspout is a sign that the gutters are draining into the sewer system instead of the storm drain or onto the grass. Smoke that pours out of the cleanout pipe in the yard may indicate a broken or missing cap.

Maintenance crews armed with cameras take photos and document the results. Finally, homeowners are notified by mail if their plumbing has leaks.

Down spouts, yard drains and cleanout caps are easy and inexpensive to fix and must be promptly corrected by the property owner. Scheduling to correct the more costly problems may be negotiated with the City. If the problem is underground on private property, homeowners may have to pay to replace the pipes. Ongoing noncompliance may eventually result in fines.

ENV smoke testing crews find that people are usually pleased to learn something about their sewer system and amazed to learn that about half of the extra water entering the system during heavy rains comes from residential property. Once homeowners understand what we are doing, the reaction is very positive.

National studies estimate that private property sources account for 50% of the unwanted water in the system. Previous tests conducted on Oahu have been consistent with these results.

Reducing and preventing collection system spills to the maximum extent possible is the city's goal. It is also one of the requirements of the 1995 Consent Decree between the City, state Department of Health and the U.S. Environmental Protection Agency.

Without a concerted effort on the part of all residents to control storm water overflow, the only alternative is to increase the capacity of the wastewater treatment plant or construct larger lines and storage tanks—an extremely costly solution.

Last Reviewed: Tuesday, May 10, 2011