How Far to Plant an Oak Tree In a Septic Drain Field?

How Far to Plant an Oak Tree In a Septic Drain Field?

Clogged septic systems cost homeowners thousands of dollars every year in replacement and repair. Tree roots are often found to be responsible for the congestion, a situation that may be avoided by planting specific types of trees a minimum safe distance from septic tanks and drainage fields. Oak trees are thought to be one of the safest trees to plant in these locations, since their origins systems aren’t as widespread and are far less invasive than those of other species.

Minimum Distance

Oak trees (Quercus spp.) Are one of the few trees that origins are classified as not posing much of a threat to septic systems, drainage fields along with other underground pipes. Still, the evidence detailing oak tree root growth contradicts this theory, as the origins of a mature oak tree may fan out as much as 90 or more feet from its base. Recommended planting distances of 15 feet are geared toward young trees whose origins systems are still developing but do not consider the way in which oak tree roots develop, which would imply a minimal planting distance equal to the tree’s height at maturity. This translates to a distance equal to or greater than 70 feet from a tree that’s 70 feet tall, and this disregards the frequent thinking that a pine tree’s root system normally does not stretch much farther underground than its highest branch width.

Oak Root Development

Oak trees spread by way of acorns that fall from the trees in early autumn in most regions. Under the right conditions, acorns become quickly established in which they drop, sending down a root often within days of coming into contact with the dirt. This original root, or tap root, can travel vertically into the ground to as much as 5 feet prior to the tree’s first leaves begin to develop. The seedling’s energy then shifts to the areas of the plant above the ground, along with the tap root starts sending out side, or posterior, roots that grow horizontally away from the plant. Lateral roots keep growing in this way in search of water and nutrients and are naturally attracted to the sort of very fertile nutrient-rich, dirt normally found near septic tanks and leach fields. Even if a pine tree is supposed to be located a safe distance from a drainage area, there’s absolutely no guarantee that its origins won’t search out its effluents, especially if it is growing in an area that sees little yearly rainfall.

Oak Tree Placement

Oak trees, including bur oak (Quercus macrocarpa), white oak (Quercus alba), and northern red oak (Quercus rubra) are also regarded as low risks to septic systems by some establishments, such as the Morton Arboretum in Lisle, Illinois. Though other types of trees such as willows are natural water seekers and shouldn’t be implanted in the neighborhood of a septic system in any way, trees such as oaks might be considered risks due their increased drought tolerance. Planting oaks at least 50 feet off — or more, if the tree is going to develop into a significant one — in the farthest point of a drain area provides a relatively wide buffer zone, especially in regions that experience adequate rainfall.


Oak tree roots should not be trusted to remain in their own planned boundaries even if they are implanted what is thought to be a secure distance from septic systems. Additionally, oak trees can easily be threatened by any kind of root disturbance that includes building too near or above them, moving the dirt over or near them, or attempting to trim any that are protruding through the soil’s surface. Along with being a potential threat to sewage systems, a pine tree’s vulnerability to any kind of disturbance reinforces the need to plan where it goes well in advance of the actual planting, since it will be too late to make any changes once the tree is created other than to cut it down. In short, find oak trees in regions where there is the least likelihood that they will become problematic.

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