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Lateral Line

A Guide to Your Private Sewer Line

What is a lateral line?

The lateral line connects your home or building to the public sewer system. Wastewater from your sinks, showers, toilets, dishwashers and washing machines flows through the lateral line to the public sewer system.

Who is responsible for maintaining and repairing the lateral line?

The lateral line is private property. It is the property owners' responsibility to maintain and repair the lateral line.

It’s important to keep the lateral line clear of obstructions and in good repair. This will greatly reduce the risk of blockages, clogs and water backups.

What causes lateral lines to become blocked or obstructed?

Lateral lines can be blocked or obstructed by items flushed down the toilet or washed down the drain, as well as tree roots, grease, and other obstructions.

How do I know if my lateral line is blocked or damaged?

Some signs that your lateral is blocked or damaged include slow draining, water pooling around the basement floor drains, sewage smell inside or outside the building, wastewater leaking from cleanouts, and wet ground in your yard.

Will insurance cover repairs to the lateral line?

Most homeowners'/business owners' insurance policies do not cover damages caused by a problem with the lateral line. You should verify coverage with your insurance agent.

Many area municipalities offer lateral line insurance for their residents. This insurance helps offset the cost of repairing lateral lines. For additional information, contact St. Louis City at (314) 647-3111, ext. 1008, St. Louis County at (314) 615-8427, or your municipality.

How do I get the lateral line repaired?

If you do not qualify for a municipal lateral line insurance program, then you should contact a licensed professional plumber. MSD cannot offer plumber or specific company recommendations.

How do I maintain the lateral line?

  • Have the lateral line inspected and cleaned annually by a licensed plumber.
  • Do not plant trees or large shrubs near the lateral line. Roots can enter the lateral line and cause a blockage. If roots enter your lateral line, call a license plumber to clear the line.
  • Do not pour grease down the sink. When grease cools, it can build up in the lateral line and cause a blockage. See Grease Management for how to properly dispose of grease.
  • Do not flush diapers, feminine hygiene products or other non toilet paper materials down the toilet. These items can block the lateral line.
  • In some areas, downspouts are connected to the lateral line. Debris from the roof can wash into the gutters and eventually reach the lateral line. Keep gutters clean to keep debris from blocking the lateral line.
  • Repair or replace damaged lateral lines as soon as possible.