Managing and Protecting LA's Underground Sewer System

Every time you flush a toilet, run a washing machine, or open a sink faucet, the wastewater has to go somewhere safe. Our wastewater system operates 24 hours a day, 365 days a year to serve more than four million customers in the City of Los Angeles, along with 29 neighboring contracting cities and agencies.

To keep this critical system flowing, the State of California requires publicly owned sanitary sewer systems to develop and implement a formal Sewer System Management Plan (SSMP). This plan details our specific operational goals and emergency response procedures for handling sewer overflows.

To ensure absolute compliance, the City of Los Angeles conducts an official audit of our system management plan every two years. Our master plan was successfully updated following a comprehensive audit, which confirmed that LASAN’s maintenance and containment strategies are highly effective at controlling accidental sewer spills and protecting public health.

Because our pipeline network is buried deep beneath busy city corridors, LA Sanitation and Environment (LASAN) works alongside the Department of Public Works to utilize three specialized construction techniques. This allows us to scale our work based on neighborhood density and soil conditions:

• Trenching: The traditional method for shallow sewers under 20 feet deep. Crews dig an open trench, place the pipe, backfill the dirt, and repave the street surface.
• Microtunneling: A popular choice for high-density neighborhoods. Instead of tearing up long stretches of road, contractors dig two access pits and lower a laser-guided, remote-controlled Microtunnel Boring Machine (MTBM) underground. No workers enter the tunnel, and the pipe is pushed smoothly into place behind the machine.
• Large Bore Tunneling: Used for our largest interceptor sewer pipelines, which span eight to ten feet in diameter. A massive Tunnel Boring Machine (TBM) allows city engineers to route critical trunk lines deep beneath hills and complex urban geography without disturbing the neighborhoods above.

When a sewer pipe experiences wear and tear, our repair teams use trenchless technology to fix the damage without digging up your street:

• Pipe Jacking: New pipe sections are pushed directly inside the old, cleared pipeline and cemented watertight.
• Pipe Liners: A flexible plastic liner reinforced with glass fibers is inserted into the existing pipe and cured in place, creating a durable new pipe inside the old one.

When we must work directly in your local streets or alleys to update aging infrastructure, our teams follow strict protocols to minimize disruptions to your daily routine.

The public sewer mainline belongs to the city, but the pipe connecting your home or business to that mainline is a private line called a sewer lateral. It consists of an upper lateral (from your building to your property line) and a lower lateral (from your property line to the middle of the street).

Property owners are responsible for the maintenance and repair of their entire lateral. If a problem occurs inside this line, it can cause sewage to back up into your home.

Essential Prevention Steps for Property Owners:

• Fight Fats, Oils, and Grease (FOG): Never pour cooking grease down a sink or garbage disposal. It solidifies inside pipes like concrete. Scrape food leftovers into the trash, and pour cooled liquid grease into a sealed container inside your black trash bin.
• Defend Against Tree Roots: Roots seek out moisture and can crawl into tiny cracks in private pipes, creating massive blocks. Property owners must hire a licensed plumber to clear roots from private lines.
• Check Your Backwater Valve: If the lowest plumbing fixture in your home (like a basement tub or shower) is lower than the street manhole cover, your property requires a backwater valve. This device automatically shuts to stop mainline sewage from backing up into your home. These require a permit from the Los Angeles Department of Building and Safety (LADBS) and regular plumbing checks.
• Report Public Sewer Odors: We use natural microorganisms in our permanent Air Treatment Facilities (ATFs) to safely eat away foul sewer gases without harsh chemicals. If you smell a public sewer odor in your area, please report it immediately to our 24/7 Customer Care Center at 1-800-773-2489.

Why is the property owner responsible for the lower sewer lateral if it is located under a public street?

In the City of Los Angeles, a sewer lateral strictly serves one individual property lot. Because it provides a private, direct service rather than a shared community benefit, municipal regulations dictate that it cannot be repaired at the expense of the city's utility ratepayers.

Can my everyday family plumber perform repairs on my street sewer line?

Your plumber can perform any repair work located inside your private property lines if they hold a standard plumbing license. However, if the repair requires digging or working within the public right-of-way (such as under the sidewalk or street), a specialized Class "A" Permit must be obtained through the City's Bureau of Engineering.

What should I do if I suspect my property needs a backwater safety valve?

We strongly encourage you to contact a licensed plumber to evaluate your lowest plumbing fixtures against the street's elevation. If a valve is required to protect your home from public blockages, your contractor can secure the proper plumbing installation permit directly through the official website at ladbs.org.