Using the Lawn Space Over the Septic Tank
Updated: Feb 8
Do’s & Don’ts for Spring Landscaping over the Septic Tank
Can I BUILD over the Septic Tank?
Can I DRIVE over the Septic Tank?
Can I PLANT over the Septic Tank?
These are the questions we will cover in this post to help you make the most of your Spring Landscaping opportunities this year.
Can I build over the Septic Tank or Leach Field?
It is not recommended to build over the septic tank or leach field.
Access to the tank is necessary for inspection and maintenance. Anything built over the tank would have to be removed for pumping and repairs. Additionally, the weight of anything built over a septic tank could damage the unit. The gasses that might escape the tank are very harmful to people and in a worst case scenario could actually be explosive damage to the structure. Building over leach fields can compact soils or damage the underground apparatus and cause the septic system to fail.
So while you are envisioning that expansive new deck or gazebo in the back yard, just make sure you are careful to avoid the septic tank and leach field in your designs.
Can I drive or park over the Septic Tank or Leach Field?
It is not recommended.
While this area should not become a parking area, limited driving of light or personal vehicles should not harm a properly installed leach field. Under wet conditions, however, any heavy packing of the earth over the distribution lines will have a negative impact on effectiveness, so steer away from having any vehicles over the area during these times.
Avoid having very heavy vehicles, like those used for oil deliveries, pool water filling, and cement delivery, drive directly over the field ANYTIME!
Can I plant anything over the Septic Tank or Leach Field?
Yes, but you need to be careful what you choose to plant over the Septic Tank
Woody plantings like trees or shrubs can damage the underground apparatus. The root systems of trees can clog your drain lines by penetrating the holes in the pipe system. No large or fast-growing trees/shrubs should be planted over or near the septic tank system. A good rule of thumb to follow is [height of mature tree = distance needed between base of tree and the drain field].
So, if you have a Maple tree that will reach 40ft when it has matured, plant the tree 40 feet from your drain field. This may be disappointing if you have a small lawn; however, there are alternatives:
Plant trees with more shallow root systems
Install Root Barriers to keep roots from invading the drain field
If you have large trees in your yard planted to close to the drain field, you may need to consider having them removed or at least having a root barrier installed before damage is done. If you have had damage to your system from roots, you can install the barrier once you remove any roots that have attached themselves to your system. *This may better be accomplished with a company that offers Septic Tank Repair options.
SHALLOW ROOTED TREES that you can plant over the Septic Tank (or close by)
SHALLOW ROOTED SHRUBS that can be planted over the Septic System
WORST PLANTS TO PLANT OVER THE SEPTIC TANK or LEACH FIELD
Maples (other than Japanese Maple)
Vegetable or fruit gardens could be contaminated if placed too close.
You should never plant an edible garden over the leach field of your septic system! Contamination from the ‘leaching’ can occur. Most people are trying to eat more healthy and choose Organically Grown whenever possible, but this is not the spot you want to plant your veggies! As a general rule for any gardening over the leach field,
do NOT add soil to the area
do NOT mulch too heavily
do NOT water plants more than absolutely necessary
do NOT dig very deep
ALWAYS wear Quality gloves
Plants Prevent Erosion & Can Be Beneficial Over the Septic Tank & Leach Field
Landscaping the area with native plants is a very appropriate and beautiful way to utilize the space while also protecting it.
Choose plants with shallow root systems like Perennials and Ornamental Grasses. If your area is sunny, choose from the following:
Images: Cardonna Salvia, Dephinium, Mango Popsicle Torch Lily, Firebird Coneflower
Black Eyed Susans
Perennial Bachelor Buttons (like Amethyst Dream)
Coneflower (attracts Goldfinches)
Stella De Oro Daylily (hardy- needs very little care)
Kniphofia (Red Hot Poker or Mango Popsicle are two)
Chocolate Drop Sedum
If your area is mostly in the shade (from structures or tree line), use the following:
Images: Spotted Deadnettle, Hosta, Hakone Grass
Fringed Bleeding Hearts
Bunchberry (Dogwood genus)
Spotted Deadnettle (silvery sheen to foilage)
Hakone Grass (works well with Japanese Maple)
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