Chances are that the area around your septic system is devoid of any large plants, patios, or other fixtures. After all, the general wisdom is that you should avoid both any major landscaping around a septic system. This is a somewhat good rule to follow since roots can twine around pipes and cause damage. However, plants also absorb excess moisture and slow erosion, so doing some landscaping around your septic system might not be the worst idea.
It is primarily the drain field pipes that you have to worry about when planting around septic tanks. You do not want roots penetrating the perforations and clogging the system. All of the parts of this carefully tuned system must be functioning properly, or else the result is a costly problem.
Landscaping Do’s and Don’ts
- Use plants that do not require much water. This prevents plant roots from searching out water and messing with your system. Try shallow-rooted herbaceous plants like flowers and ground cover.
- Space your plants fairly close to each other to control erosion when planting quarts, gallons or plugs. This will also suppress weeds.
- Think about the future growth of any trees, shrubs & bushes and how that growth will affect access to the septic tank lids, leach field and sprinkler system.
- Mark the location of your access hatch with a potted plan, riser cover or lawn ornament right above it. This makes it easier when it comes time to dig it up.
- Let tall Kentucky bluegrass or other lawn grow over the patch of land covering the septic tank.
- Consider planting perennials. Grasses and perennials both have a shallow root system that should do no harm to your tank or drain field.
- Use small, non-woody ground covers
- Consider shallow-rooted trees and shrubbery (such as cherry trees, dogwood trees, holly shrubs, azalea shrubs and boxwood shrubs) for areas around the septic system, but keep them at least 10-15 feet away from your tank.
- Get so worried about plants/grasses damaging your septic tank that you leave the area barren. Some grasses and plants are great at absorbing excess moisture around the drain field and helping prevent issues from over-watering.
- Over-water your lawn to get newly planted vegetation growing faster. Overwatering can compact soil over your leach field and case the septic system to get backed up.
- Grow any root vegetables in the area of your system. These nutrient-absorbing plants may have issues with bacteria if placed too close.
- Put down plastic sheeting or install ponds. These features prevent proper drainage from tank to leach field.
- Create walkways or high traffic paths over the septic tank or leach field.
- Forget that fencing and gate placement can affect septic pumper truck access. The hoses on the truck are heavy and we don’t recommend going over fences with them. Most pumpers like to have access within 50 feet from the truck.
- Plant shrubs or trees on the septic system. Trees should be planted a minimum of 20 feet away, but trees that are known for searching out water should be planted a minimum of 50 feet away. Shrubs may be placed next to the system.
- Grow nutrient-loving vegetables on the septic system. While it may seem ideal for a garden, contamination is a concern depending on how well your soil filters bacteria. As a precaution, Virginia Tech Urban Forestry expert Susan Day recommends growing aboveground vegetables rather than root vegetables nearby.
- Install ponds, plastic sheeting or high maintenance plants that interfere with the drainage system.
- Create areas of increased foot traffic. The more foot traffic, the more soil becomes compacted.
Plants Safe to Grow Over Septic Tanks and Drain Fields
As long as you carefully select the landscaping for near your septic system, you do not have to overly stress about the potential of damage to septic systems caused by roots that you abstain from planting these areas altogether. Growing the right kind of vegetation here is not only permissible but actually advisable. Plants will prevent erosion and suck up some of the excess moisture from the drain field.
Perennials and grasses (including ornamental grasses) work best around your septic tank and drain field. Their shallow root systems are less likely to invade the underground system and cause it damage. For the same reason, small, non-woody ground covers are a good choice. There are, of course, many examples of such plants, so you will want to narrow down your choices.
It is not safe to eat food crops grown in the ground around a drain field because eating them might entail ingesting harmful bacteria. If you must grow trees and shrubs, shallow-rooted kinds are better to grow around septic tank drain fields. Shallow-rooted trees and shrubs include:
- Dogwood trees
- Japanese maple trees
- Eastern redbud trees
- Cherry trees
- Azalea shrubs
- Boxwood shrubs
- Holly shrubs
The Worst Plants to Grow Over Septic Systems
Generally, avoid planting large, fast-growing trees. But, in addition, some of the worst offenders are trees and shrubs with root systems that aggressively seek out sources of water. They are not fussy about the water source they tap into, meaning the pipes in your septic tank drain field are very much fair game. Weeping willow trees are a notorious example. There are many trees and shrubs to avoid, but here is a small sampling:
- Pussywillow shrubs
- Japanese willow shrubs
- Weeping willow trees
- Aspen trees
- Lombardy poplar trees
- Birch trees
- Beech trees
- Elm trees
- Most maple trees other than the Japanese
- American sweetgum trees
- Ash trees
- Tulip trees
A layer of vegetation over the drain field, such as a lawn, is recommended to hold soil in place and increase the efficiency of the system. However, certain guidelines should be followed to avoid costly and unpleasant experiences. Perhaps the best advice would be to keep the landscaping over this area free of trees and shrubs. The optimal performance of your septic system should be the foremost consideration, but a cost/benefit analysis of using certain plants will have to be considered by each homeowner on an individual basis.
At West Coast Sanitation, we know that you do not have time to deal with septic problems. If you think that your system is being affected by invading tree roots, please give us a call at (951) 780-5922 right away. We have professionals ready to answer your questions and get your system working properly again.