Plants, Septic and Failures
rural homes use private septic systems to handle household waste
and are not hooked up to any municipal sewer system. When septic
systems do not function properly, humans may come into contact with
wastewater that contains disease organisms and other harmful substances.
There also can be a significant cost to repair the system. Failure
of the system can be caused by lack of proper maintenance, overuse
of water in the household, or improper design of the septic system.
But, another reason that can cause failure and should be of concern
to home gardeners is the interference of plant roots in the systemís
drainage leach field.
Possible indicators of a failing system includes a sulfur or rotten
egg smell in the vicinity of the system or indoors, water and possibly
solids surfacing in the lawn near the drainfield, or sewage backing
up in the house.
Solids from the home septic system settle and build up in the septic
tank, which should be cleaned periodically. The remaining water
and finer material goes out into a drainfield so it can be absorbed
down through the soil profile. If tree or shrub roots enter these
drain tiles, they can clog up the system and cause backups or other
failures, possibly even a replacement of the drainage system. Costs
for drainfield replacement can often be several thousand dollars.
The standard recommendation of University of Illinois Extension
Educators is to avoid planting anything above the septic tank or
leach field. Care should also be taken to avoid plantings that are
nearby enough to have roots enter the drain tiles. Not only can
damage be done to the system, but there can be a potential high
cost to move, remove, or replace trees and landscape plantings.
Most local health officials also indicate not to plant near septic
The Morton Arboretum in Lisle, IL has published a list of trees
and shrubs that commonly invade septic systems and some that are
less of a problem. Some common invaders on their list include red
and silver maple, weeping willow, American elm, red cedar, forsythia,
pussy willow, red-osier dogwood and others. Some that they indicate
are less common invaders include sugar and Norway maple, white and
green ash, white oak, and white pine, in addition to others. Again,
though, the safest protection is to avoid planting on or near septic
fields. Well designed and maintained septic systems will be trouble
free for many years.
April - May 2004: Foolproof
Perennials | Plants, Septic and Failures | Can
I Prune Now? | Selecting Trees