What Can You Put on Top of a Septic Field? Your Guide to Landscaping Over Leach Lines

Many homeowners hyperfocus on septic tank health, and while that’s important, the septic drain field or leach field is just as crucial to take care of. Your drain field sits under a large portion of your property, and knowing where it is is important for maintaining septic system health and functionality. Explore what you can put on top of a septic field, what you can't, and how to avoid damage to your system in the process.

How a Septic Leach Field Works

When waste flows out of your home, it flows out of your sewer main line and enters into a multi-chamber septic tank before it reaches your leach field. A few things happen in the septic tank:

• Solid waste separates from liquid waste

• An air compressor aerates the liquid waste (in an certain types septic systems)

• Bacteria in the tank break down the organic matter

As this process comes to an end, a pump moves the partially treated liquid waste to the drain field. This consists of a series of perforated pipes that run under the ground. The waste exits the pipes and mixes with bacteria in the surrounding soil, which finishes treating the waste. The water eventually soaks back down into the groundwater.

How to Landscape Over Your Septic Drain Field

Now that you understand the basics of how a septic leach field works, you can plan out what landscaping features you can plant over the field. You want to plant lightweight vegetation over the drain field that either has very shallow roots or doesn’t have woody roots that could grow into the perforated pipes, creating clogs or breaks.

Grass Is a Great Option

Planting grass over your drain field is one of the best and most common options. Grass won’t put your leach field at any risk of damage for a few reasons:

• It’s super lightweight

• Its roots are shallow

• Its roots aren’t strong enough to break your drain field pipes

Plus, most drain fields are located in the middle of the rear yard, so most homeowners will want this area covered with grass anyway.

Flower Gardens Will Flourish

Flower beds are another popular option for placing over septic system leach fields. The bacteria surrounding the leach field and the effluent coming out of your perforated pipes will keep your soil beautifully fertilized, so flowering plants should have no issue thriving over a drain field.

Similar to grass, flowering plants aren’t terribly heavy, and they have relatively weak, shallow roots that won’t pose any danger to the pipes.

Lightweight Landscaping Features Are Acceptable

In addition to vegetation, you have the option of installing lightweight landscaping features over your drain field. Some options include the following:

• A non-permanent, lightweight swing set

• Open-air dog run

• Small fences (just be sure the posts don’t go too deep)

Whenever you place structures over your drain field, you might want to call a septic tank company near you to inspect the drain field and make sure what you’re installing won’t be too heavy over the buried pipes. A professional can also help you dig holes for installing fence posts or other structural components without damaging your leach field.

What NOT to Put Over Your Septic System’s Leach Field

Septic system drain fields are somewhat delicate, so the list of landscaping features you shouldn’t put over them is longer than the things you can.

Shrubs, Bushes, or Trees

Septic system leach field pipes sit between 6 and 36 inches under the ground, often at a depth of a foot and a half. As such, planting any vegetation with woody root systems isn’t recommended, as the roots can easily damage the pipes.

Roots from trees and larger bushes are especially problematic because they can crack the drain field pipes and cause the effluent to seep into the ground too quickly. This could pose an issue for water quality.

Vegetable Gardens

Vegetable gardens might seem like a great option for planting over a septic drain field because they’re lightweight and have shallow roots, but it’s not recommended. According to the University of New Hampshire, the effluent can contaminate the soil if you run into issues with leaks, at which point it would be unsafe to eat the produce.

Patios and Other Heavy Landscaping Features

You should also avoid any heavy landscaping structures over leach fields, as the weight of concrete, pavers, and other dense building materials can compact the soil and crush the drain field pipes, leading to serious issues.

Some landscaping features to avoid over your leach field include the following:

• Paver patios

• Flagstone patios

• Concrete patios

• Decks

• Concrete or paver walkways

• Pools and spas

• Built-in fire pits

• Sheds

How to Avoid Damaging Your Septic Drain Field

Keeping your leach field in good working condition doesn’t take a lot of work, but it does take some careful planning and ongoing maintenance. Follow the tips below to help make sure your drain field continues to work properly for years to come:

• Only plant grass and lightweight plants with non-woody roots over the field

• Avoid patios, walkways, decks, and other heavy structures above the drain field

• Don’t plant trees or bushes within 10 feet of the leach field

• Have a septic system inspection done every two to three years

• Report issues with sewage backups, a soggy lawn, or unusually green grass over your leach field immediately

It takes some money and effort to maintain your leach field, but doing so will almost always be more affordable than the cost of a new septic system.