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Beneath the Surface: Exploring the World of Sewers

About the City’s Sewer System

Los Angeles operates and maintains the largest wastewater collection system in the United States. It serves a population of more than four million within a 600 square mile service area that includes Los Angeles and 29 contracting cities and agencies.

The City’s more than 6,700 miles miles of public sewers convey about 400 million gallons per day of flow from residences and businesses to the City’s four wastewater treatment and water reclamation plants. Information on how the City manages its vast sewer system may be obtained in the Sewer System Management Plan (SSMP).

LA Major Interceptor/Relief Sewers

system map s

Most sewers are in good working order but some are being repaired or replaced, as part of the 10-year LA Sewers Program and the Collection System Settlement Agreement (CSSA). The CSSA is a legal agreement that defines the maintenance and construction projects and schedules.

These include sewers that are very old, seriously deteriorating, or too small for the area they serve. The City has developed rigorous maintenance and construction programs to keep our sewers in reliable condition.