How Much Weight Can a Leach Field Hold?

If you have a septic system to handle wastewater and sewage at your property, you also have a leach field with pipes just under the ground. How much weight can a leach field hold? Most experts say that the maximum weight a leach field can hold is about 10,000 pounds, but even then, it can’t hold it for long. It’s best to avoid putting large or heavy objects atop these underground perforated pipes. Learn more about the best ways to protect your leach field from weight overload.

Why Should You Worry About Weight on Your Leach Field?

With a septic system, the septic tank holds the solids and liquid waste that travel through your home’s sewer system. The liquids slowly seep out of the septic tank through a series of perforated pipes into the leach field. The pipes sit on a layer of gravel and sand with normal soil over the top of them.

The perforated pipes for the leach field are 18 to 36 inches underground. With such a shallow depth, significant weight aboveground could damage the pipes by crushing them or forcing them to shift out of place. 

Such damage could cause the septic system to stop working as intended. You could have broken pipes if you see signs like standing liquid sewage above the leach field or extremely damp soil with a foul odor. Eventually, waste may begin backing up into your home.

A local septic tank company can inspect the leach field for damage and provide options for fixing the issue. Repairing this type of damage is extremely difficult, so the best option is always to take steps to avoid introducing excess weight.

Lightweight Items That Can Go Over a Leach Field

You can use the ground over the leach field to plant certain types of landscaping or for some recreational activities without creating excessive weight.

Plants and Grass

Only use shallow-rooted plants in your leach field. Grass is the best option for plants to use over the leach field to minimize weight and deep root penetration. 

Play Areas

Small kids’ play areas are safe over the septic drainage field, as long as you don’t bring in heavy equipment. Simple swing sets are fine, but you don’t want to drive support posts deeply into the ground.

You can also set up temporary nets for badminton or volleyball in the area. Just don’t drive support posts deeply into the ground. Playing recreational baseball, softball, soccer, or football with several people is fine in this area.

Lawn Mowers

A lawn tractor or riding mower is not too heavy to use over the leach field. You can use a walk-behind mower, too. Most people plant grass over the septic field, and mowing the grass is safe to do.

Open-Air Dog Runs

Building a dog run with a chain-link fence is safe atop a leach field, as long as you don’t have deeply buried posts. Avoid placing a roof over the dog run, as this will block the sun and kill the grass, affecting oxygen levels in the soil.

If the dogs like to dig deep holes, this could damage the leach field, so be aware of this issue.

Heavy Items You Should Never Place Over a Leach Field

You should avoid putting anything that is a few thousand pounds over your leach field. Here are some examples.

Trees

Do not plant trees atop or near the leach field, even small ones. The weight of a tree is problematic—some grow to be several tons—but the deep roots also present a problem.

Raised Garden Beds

Avoid using a raised garden bed in this area, as the weight of landscaping stone, railroad ties, and extra soil could damage the perforated pipes.

Sports Courts

Concrete or asphalt courts for tennis, pickleball, or basketball should never go over the septic drainage field. The weight of these materials is not safe for the septic pipes. Additionally, these materials would starve the soil underneath of oxygen, which would affect drainage in the leach field.

Large Groups of People

Avoid having more than a dozen people use the area at the same time, especially for recreational volleyball or flag football. The weight of this many people in a concentrated area could cause damage.

Structures

Don’t place structures with significant weight on the drain field area. If you build a structure with 2-by-4s or 4-by-4 posts, it will likely weigh too much.

Heavy Vehicles

Avoid driving or parking motor vehicles or large equipment over the top of the septic field. Even if the weight of the vehicles doesn’t damage the perforated pipes, it will compact the soil, which could dislodge the pipes.

Deck or Patio

Never build a deck or patio over the septic field area. These items are far too heavy and can prevent oxygen from reaching the soil.

Aboveground Swimming Pools

Do not put any size of aboveground swimming pool over the leach field. Pool water has a lot of weight that could damage the system. If the water spills out and saturates the soil, the leach field may stop working properly, leading to septic problems.