Some homes in our sewer service area are prone to sewer backup due to certain topographic conditions. These homes may benefit from an anti-flooding device to reduce this risk. LACSD offers free inspections of private sewer laterals to determine if an anti-flooding device could protect a home or business from unwelcome sewer backups.

A private sewer lateral is the pipeline that connects a home’s wastewater flows to the District’s sewer collection pipeline. The connection to the sewer main is usually located in the street or near the property line. Private sewer laterals are owned and maintained by the property owner, including any part that extends into the street or public right of way.

Blockages and sewer backups are unfortunate events. Several factors can contribute to the cause of a sewer backup, including:

• Tree roots
• Customer disposal of fats, oil, and grease down household drains
• Topography and slope of the pipelines and the properties served
• Age and deterioration of sewer pipelines
• Multiple connections to a single sewer lateral
• Absence of sewer backflow prevention devices at individual properties

At-Risk Properties

LACSD conducted an audit to identify which homes may potentially be at risk for sewer backups but it is not guaranteed that all homes were identified. The District placed a priority on homes that were found to have one or more of the following conditions:

• Property in a location where a pipeline serving steeper slopes meets sewer lines serving flatter areas.
• Structures with a wastewater outlet that is less than 48” above the nearest upstream manhole.

If you have either of these conditions, a blockage in the main line could result in sewage flowing backward into your private sewer lateral. In the best case scenario, the backup would be discharged through a clean-out in your private sewer lateral if one is installed. In the worst case, the backup will flow into the lowest drain in your home. Installing a clean-out and/or antiflood device will protect you from this unfortunate situation.

Property owners can protect their property by installing an outside clean-out equipped with an approved anti-flooding device. This clean-out and anti-flooding device should be installed as close as possible to the outside of the foundation wall. The clean-out should extend approximately three inches above the finished grade of the ground so that access can easily be obtained.

It is the property owner’s responsibility to maintain their private sewer lateral and protect themselves from damage that could potentially occur from a sewer backup. Any customer that has been identified by the District with a risk for a sewer backup, and chooses not to install an anti-flooding device, is responsible for any and all damage resulting from a sewer backup incident.

There are several types of anti-flooding devices listed below. Each of them, if used properly, will protect the property against sewer backups.

• One-way directional flow (Clapper Valve) – this is the most certain form of protection but requires additional maintenance efforts. This device should be installed in a vault for easy access.
• Pop off cap – this can be installed on an outside clean-out and must not have any restraining clamps that prevent the cap from easy removal. The clean-out needs to be approximately three inches above the surface of the ground and exposed for easy access. The cap must remain on the clean-out to avoid stormwater entering the sewer system.
• Spring loaded relief valve – this is installed on the outside of the clean-out. The clean-out must have a threaded coupling into which the relief valve can be installed. This should only be installed on a cleanout that has the appropriate height and location, as close as possible to the outside of the foundation wall and approximately three inches above the level of the ground, to ensure the relief valve will open freely.
• An anti-flooding device needs to be kept clear from debris that might prevent it from working properly, including pine needles that might block access. At least twice per year, check to make sure it is in proper working condition.

Contact your local professional plumber to install a clean-out and/or antiflooding device. The steps involved include digging a small hole to expose the sewer lateral, cutting and removing a small portion of the pipeline, and installing new pipe and fittings for the outside clean-out and anti-flooding device components.