What Are Septic Lateral Lines?

By Shelley Frost

November 09, 2024

What happens to the waste in a septic system once you flush it? You know there's a big tank in the ground, but you might not know exactly what the components are in a septic tank and leach field.

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Septic lateral lines are one of those mystery components that play an important role in getting rid of wastewater effectively.

What Are Lateral Lines in a Septic System?

The two main parts of your septic system are the tank itself, where all the waste goes initially, and a large leach field. Once the scum and sludge layers settle in the tank, the water exits the tank and goes into the leach field. The septic lateral lines are the pipes that run through the field and distribute the water into the ground. Typically made of PVC pipe, lateral lines contain lots of holes so the wastewater can seep away into the surrounding soil.

Septic system lateral lines can work differently depending on the type of system you have. For example, in a conventional system, you typically have more lines that have gravel around them, followed by soil that has aerobic bacteria in it. This septic lateral line design continues to treat the water to ensure safety. Meanwhile, an aerated septic system doesn't need as many lateral lines because the water is treated primarily when it exits the tank.

How Long Are Septic Lateral Lines?

A septic tank lateral line typically can't be more than 100 feet long. The total length of lateral lines the system needs depends on various conditions, including the type of soil and tank. Septic systems often need multiple lateral lines to have adequate coverage. That means systems usually have multiple trenches with different lines, none of which will be longer than 100 feet.

How Deep Are Septic Lateral Lines Buried?

Most lines are buried in trenches that are between 18 and 30 inches deep and 18 to 36 inches wide. It's common to have about 12 inches of gravel in the bottom of the trench. Because the lines aren't very deep in the ground, it's important to carefully position the septic tank leach field.

How Do You Know If Lateral Lines Are Clogged?

You can't visually inspect your septic lateral lines since they're buried, but you might notice signs of a problem in the way your plumbing works. Some of those clues include:

Slower drains
Bad odors inside your home or outside near the leach field
Sewage backups into your home
Puddles or collapsed soil over the leach field
Extra-green, tall, lush grass

Clogs often happen when there's a problem with the tank. When the tank has issues, solids could enter the pipes and drainfield, creating clogs. Blockages may be common in older systems where there's more likely to be buildup.

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Can Septic Lateral Lines Be Cleaned?

It's possible to clean out clogged lateral lines with a sewer jetter. The pressurized water can help clear clogs in the lines. This is a job for a septic tank professional. They have the equipment to handle the work and know how to do it safely. It's important to call a professional at the earliest sign of a clog in the leach field. This gives you the best chance of saving it and restoring function to it.

How Can You Protect Your Septic Tank Lateral Lines?

Using your septic tank properly allows it to break down waste and reduce the risk of solids entering the lines. This means only flushing human waste and toilet paper and being careful of what goes down your drains. Chemicals that go down the drain can kill the bacteria in the tank that break down solids. Using your garbage disposal can cause problems because it could add more solids to the tank that are difficult to break down.

Outside, you can protect the lateral lines by using the leach field area with caution. Don't drive over the leach field, as this can compress the soil and affect how well it drains. Avoid planting trees or shrubs with deep roots in the area. The roots can grow into the drain lines, creating blockages.

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