Landscaping for Septic Systems

Save Time and Money – Properly Landscape Your Septic System

Well designed, property installed and regularly maintained septic systems can last for many years. Your septic system is a substantial investment and protecting it from damage can save time and money. Improper (or lack of) maintenance and physical damage are the two main causes of a failing septic system. Information on regular maintenance and inspection can be found in Protecting Your Investment: Inspecting Your Septic System (PDF).  This fact sheet outlines how to landscape around your septic system to minimize damage.

Plan Ahead to Protect Your Septic System

Landscape design should not interfere with the natural function of your system. Examine your yard with the future in mind. Do you have plans for constructing storage sheds, decks, patios or other structures? Construction on or near your septic system could damage the tank, pipes or soil. The septic tank, drainfield and reserve area should remain clear of sprinkler lines, decks, patios, storage sheds, sand boxes, swing sets, paved or dirt. Know the location driveways, parking areas and walkways. Adequate access to the of your septic tank and components of the septic system is also critical for maintenance and drainfield before starting. pumping. Use common sense and plan around your septic system. Unsure of where your Know where your tank, drainfield and reserve areas are located system is? Contact Clark before beginning any landscaping work. If your septic system does County Public Health – fail, you will need the reserve area to replace the failed system. Environmental Health at 360-397-8428.

Marking Components for Access

Regular maintenance is a part of keeping your septic system working and is easier when components are well marked and easily located. Newer tanks have above ground easy access ports that many landowners would like to disguise. A tiered planter box or bench can camouflage these ports and can be easily moved to allow service. Access ports for older tanks are usually buried six inches to two feet and are difficult to locate when it comes time to pump. Bird baths or feeders, sundials, potted plants, sculptures or lawn ornaments near the access port will make it easier to locate for servicing. Consider installing risers, available from local septic pumpers, over access ports and then disguising them as discussed above.

Managing Water and Soil Properly

Keep Excess Water Off!

Direct downspouts and other surface water runoff away from your system. Your septic system is designed to handle only the water coming from your home. Additional water from downspouts, heavy hand watering, sprinklers or ponds overloads the soil and can lead to septic system failure. Irrigation systems and water features should be located at least ten feet from the edge of your system.

Vehicles and Equipment.

Limit traffic over the system to reduce soil compaction. Compacted soils retain less oxygen, reduce soil organisms’ treatment of the effluent, and reduce the system’s effectiveness. Keep vehicles larger than a riding mower off the drainfield to avoid soil compaction and damage to the leach lines. If you must cross the drainfield with a larger vehicle, make sure the soil is dry and utilize track boards for weight distribution.

Animals

Large animals also cause compaction. If you choose to allow animals to graze the drainfield area, you risk decreasing the effectiveness of you septic drainfield. Animals should never be allowed to graze the drainfield during the wet season and should be removed before grazing results in bare soil.
Gardens. Landscape fabric, plastic, bark, or mulch should not be used over your septic system. These materials reduce air exchange while bark and mulch also retain excess moisture. Adding more than a few inches of soil over the drainfield, such as for raised beds, limits air exchange and can lead to compaction. Vegetable gardens require irrigation and involve frequent cultivation and digging which can damage pipes and other components, since parts of your system may be as little as six inches underground. Although a properly functioning septic system should not add disease causing organisms into the soil, it is difficult to judge how well the system works since that depends on many factors. For that reason, food gardens should be located elsewhere. Root vegetables can penetrate your drain lines, while leafy vegetables may get soil splashed on the leaves from rain or irrigation.

Selecting Plants

Using shallow rooted, low maintenance, low water plants is the key to planting over a drainfield and near your septic system. Grass or herbaceous vegetation that can be disturbed should be planted over the tank, so you won’t hesitate to damage them. The roots of grass and other herbaceous plants can help remove excess moisture and nutrients and help the septic system work efficiently. Plants that do not require frequent dividing will limit digging and possible damage to the drainfield. Grass provides ideal year-round cover for drainfields. Ornamental grasses can be planted, as well as maintaining a traditional lawn. For a natural look, try an unmowed meadow using a meadow mix, some sold as Eco-Turf or Fleur de Lawn with native grasses and shallow rooting flowers. Other herbaceous plants can be used, but avoid plants that require frequent watering. Another option includes planting low maintenance native ground covers such as bunchberry or Lady fern or shallow rooted perennials for a cut flower garden such as Salvia, Marigold, Zinnias, Impatiens, Geraniums or Petunias. Shallow rooted plants that attract wildlife such as butterflies or birds can also be utilized. For ideas on some appropriate native plants, see Table 1. For more plant or gardening ideas contact the WSU Clark County Extension Master Gardner’s at 564-397-7725. Whatever plants you choose, your landscape can be attractive and easy to maintain, while protecting you septic system.

Landscaping Septic Systems

Table 1: Shallow rooted native plants appropriate for landscaping septic systems.

 

Sources

• Septic System Management – Landscaping and Other Activities on Your Property – Oregon State University Extension Well Water Program. Andrews, G. 2000
• Gardening with Native Plants.  Clark County Public Works, Water Resources, 2004
• Planting on Your Septic Drain Field – Virginia Cooperative Extension. Day, S. and E. Silva. 2013.
• Landscaping Your Septic System – Washington Sea Grant Program. King, T and J. Holdcroft. 2001.
• Landscaping Your Drainfield – WSU Island County Extension. Maleike, R. n.d.
• Landscaping tips with a septic system. Seattle & King County Public Health Wastewater Program. 2005.
• Landscaping Your Drainfield.  Clallum County Health and Human Services.
• Landscaping Your Drainfield – Thurston County Public Health & Social Services Department

Adapted by Erin Harwood October, 2005; Revised 2019

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