Landscaping with an on-site sewage system
Landscaping when you have a septic system requires special care. Since your yard is where sewage is treated, a landscape design should not interfere with the natural functioning of your septic system. A balanced combination of oxygen and organisms will maintain the healthy soils necessary for your system.
3 easy steps to develop a landscape design
A record drawing is a drawing of your septic system in relation to your house and property boundaries. Your septic system designer completes the record drawing after the septic system is installed. Public Health keeps record drawings on file as public information. You can request Public Health to search their records for your septic system. NOTE: Not all records are complete, and older septic systems may not have record drawings.
Avoid landscaping on or near the septic tank. Consider installing "risers" or septic tank lids to make septic tank pumping and monitoring visits easier and less time-consuming.
The septic tank, drainfield and reserve area should be clear of:
- underground sprinkler lines
- decks, patios, sports courts, or utility storage sheds
- sand boxes
- paved or dirt driveways
- parked vehicles
After locating the septic tank, drainfield and reserve area, you may now begin the design phase. Keep the tips in Step 2 in mind.
Do's and Don'ts when preparing your garden:
- Don't plant a vegetable garden on or near the drainfield or reserve area
- Plants over the septic system may be disturbed or destroyed with repair work
- Don't put plastic sheets, bark, gravel or other fill over the drainfield or reserve area
- Don't reshape or fill the ground surface over the drainfield and reserve area (just adding topsoil is generally OK as long as it doesn't exceed a couple of inches over the drainfield area)
- Grass or the existing native vegetation are the best covers for your drainfield and reserve area
- Direct all surface drainage areas away from the septic system
- Use shallow-rooted plants (see plant list below)
- Avoid water-loving plants and trees
- Do not make ponds on or near the septic system and the reserve area
Suggested plant list (provided by Washington Sea Grant Program):
Groundcovers for sun:
- Bugleweed (Ajuga)
- Carpet heathers (Calluna)
- Cotoneaster (Cotoneaster)
- Ground Ivy (Glechonma)
- Kinnickinick (Arctostapylos)
- Periwinkle (Vinca)
- Soapwort (Saponaria)
Groundcovers for shade: