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Septic Landscaping
PROTECTING YOUR DRAINFIELD
The drainfield is a critical component of your septic system. If your drainfield gets damaged it won't be able to treat wastewater from your home like it should, and that's why it's important to protect it. Keep your drainfield in good shape with these landscaping dos and don'ts:
Landscaping Do's
- Learn where your system is located
- Only plant grass or recommended plants
- Walk your drainfield to check for issues
- Direct sources of water away from the drainfield
- Use barriers or markers to prevent unwanted traffic
- Only use landscape fabric that's breathable
- Keep heavy equipment and livestock off
- If you build a fence around your drainfield, make sure it allows light to pass through
- Keep the shape and slope of the surface
- Protect septic system lids while mowing
landscaping Don'ts
- Build a patio, shed, driveway, etc. on top
- Plant trees or shrubs within 30 feet, and 50 feet for water-loving trees like willows, maples, etc. Essentially the further, the better!
- Pull out tree stumps, rototill, or dig (cut trees at ground level or grind instead)
- Plant a vegetable garden
- Put a rockery on top or nearby
- Terrace within 50ft on sloping sites
- Install a sprinkler system in or nearby
- Install an artificial pond in or nearby
- Put a firepit on top
KNOW WHERE YOUR SYSTEM IS LOCATED!
One of the most important things to know when landscaping is where your septic system is. It helps you know what to avoid when landscaping or doing other projects. If you don’t know where your system is, you can find out using OnlineRME. Don’t see them there? Your system might be too old or installed before records were required. If this is the case, you can hire a septic professional to help figure out where your system is.
PLANTING TIPS
Grass is the #1 choice! Why? Because it provides year-round coverage, has shallow roots, and allows oxygen and water to move easily through the soil. If you choose plants other than grass over your drainfield, keep these traits in mind:
Shallow Rooted | Roots can clog holes, break pipes, and cause lots of damage. Some systems can be buried as shallow as six inches underground, so it’s important to pick plants that have shallow roots.
Year-Round Coverage | Year-round coverage will prevent runoff of the topsoil above your drainfield, and it will keep the microbes in the soil happy by making sure oxygen gets into the ground all year long.
Drought Resistance | Drought-resistant plants can be good for your drainfield because they need little water. However, some drought-tolerant plants can handle dry spells because of long, wide-spread roots that reach way down where water is present (which would be your drainlines!) and could cause damage. If a plant is drought resistant, make sure it still has shallow roots.
Native Plants | Native plants are accustomed to our climate and require less maintenance. They’ll need less watering which will save your drainfield the added stress from extra water. If your drainfield is in an area where grass doesn't grow well, you can also stick with the native vegetation so long as there's nothing with deep roots.
For recommendations on plant types, contact a nursery professional.
- Can I just leave my drainfield blank?
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Sand, bark, wood chips, gravel, or plain dirt over your drainfield may sound easy, but these materials keep oxygen from getting into the ground, and bare soil can start to wash away. Plants help with oxygen exchange, keep soil healthy, and hold dirt in place so your drainfield can do its job.
- What about near my septic tank or pump tank?
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Risers: If you don't already have risers, installing them is a great idea. They allow for easy access to tanks during routine inspections and pumping. Protect septic lids when mowing, but do not cover with heavy or permanent objects.
Plants & Ground Covers: Things like bark, wood chips, and gravel are okay here. Wastewater is not treated in the soil next to tanks, so there isn't a need for plants. All the other advice still applies though. Don't put anything heavy over this area. If you do plant something, stick to shallow-rooted plants to avoid damage to tanks and pipes.
- What about those other lids in my yard?
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Some septic systems have lids out in the drainfield. These are access ports that allow for easy inspection of the drainfield. Make sure that your landscaping doesn't bury or hide them, and protect them when mowing.
- What about my reserve area?
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Protect this the same way as your drainfield. If you do things to damage the soil in your reserve area, it may not be useable in the future for a replacement drainfield if your current one fails.
- What are some examples of plants besides grass?
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IMPORTANT: Some drainfields are buried a few feet underground, while others are as shallow as 6 inches. If you have a shallow drainfield, not all of the plants listed below may be suitable. Try to find how deep your drain lines were installed by checking your septic records. Always consult with a nursery professional before choosing plants other than grass to make sure it has shallow enough roots to avoid damage.
Grasses for Sun
- Turf grasses
- Fescue
Ground Covers for Sun
- Bugleweed
- Carpet heathers
- Kinnikinnick
- Cotoneaster
- Thyme
- Stonecrop
- Soapwart
Plants for Shade
- Bishop's hat
- Bunchberry
- Shallow-rooted ferns
- Mosses
- Salal
- Sweet woodruff
- Wild ginger
- Wintergreen
- Japanese spurge
Wildflower meadows: This is a common suggestion for drainfields but if you do this, make sure your wildflower mix...
- Is a Washington/Northwest mix
- Specifies no noxious weeds
- Has both annual and perennial seeds
- Does not have plants that require extra water or have long roots
View this info about septic landscaping in a print-friendly format.
Still have questions?
Get technical assistance! Email SHD-EHQ@snoco.org
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Land Use
Physical Address
3020 Rucker Avenue
Suite 104
Everett, WA 98201
Phone: 425-339-5250Fax: 425-339-5254
HoursRegular hours:
Monday through Friday8 a.m. to 3:45 p.m.
Please arrive no later than 3:30 p.m.