The San Francisco Public Utilities Commission says 20 percent of the bleach to be purchased during the next three years for $14 million would be poured into San Francisco’s sewers to control the odor. “The overwhelming majority of [bleach] we purchase is for the disinfection of drinking water and sewage, not for odor control” according to a document produced by the agency.

The document comes after a report from the San Francisco Examiner about the contract.

At the time, the agency could not provide the amount of bleach it has poured down the sewers each year and how much of the bleach it plans to purchase over the next three years would be poured down the sewers. The document also comes as the Board of Supervisors is poised Tuesday to approve the contract.

“We are often approached by companies claiming to have the solution to sewer odors. Through our many years of field testing, we have yet to find the perfect solution,” the SFPUC says. The agency oversees the cleaning and inspecting of 900 miles of sewers.

Aside from the odor control, the bleach “plays an important role for water and sewer utilities by ensuring drinking water remains safe, and treated sewage does not negatively impact the environment and public health,” the agency says.

jsabatini@sfexaminer.com