What you need to know to avoid causing planting-related
Your home's sewer is
connected to the sewer "main" (a large pipe often running
under the street) via a pipe known as a "lateral" that extends
from your home, across your property and into the sewer main. Responsibility
for maintenance of this lateral varies from community-to-community,
but, in most cases the homeowner is responsible for the line at least
out to the property line.
Regardless of who is responsible, blockages in the lateral are
always bad news for the homeowner as they can lead to slow downs
or complete stoppages of the flow of waste from the home and into
the sewer main. When either of these situations occurs, an overflow
of the home's own sewage out of the lowest opening in the home (downstairs
toilet, shower, etc.) is the likely result.
Is My Lateral at Risk of Tree Root Invasion?
Depending on the age of your home, your sewer lateral may be made
of either tile, cast iron, concrete or plastic. No matter the construction,
your lateral is filled with water and other nutrients that make it
an attractive target for tree roots.
Movement of the lateral over the years due to earthquakes and shifting
soil may have created openings in it that give tree roots lucrative
targets and points of entry to the pipe itself.
Once roots find a moist spot caused by sewer lines, they'll grow
right into the pipe itself. And, that means you may be in for expensive
Of course, it's best to avoid this unhappy circumstance by knowing
what, where and how to plant trees with avoiding sewer problems
in mind! You can help by following the sewer
maintenance tips found elsewhere on this Website and by following
some simple rules for planting above or near your sewer lateral.
Sewer Smart Planting Suggestions - Finding Your
The first step in observing Sewer Smart planting rules is to know,
at least generally, where your lateral runs across your property
and into the sewer main.
One of the best ways to find your lateral is to refer to the survey
documents you likely received when you purchased your home. If you
don't have these documents, your city planning or public works department
can most likely provide copies for you to view. In some cities, they're
even available online.
No need to despair if you don't have them, though. You can determine
the general location of your sewer lateral - good enough for planting
purposes -- by following these three steps:
STEP 1: Find the point where the lateral leaves the house by
locating the clean out. For more information on cleanouts follow
STEP 2: Find the point where the lateral leaves your property
and crosses into the street by:
- a. Locating an "S" or other similar mark in or on
- b. Locating a second cleanout at the property edge, in the
sidewalk or roadway. This cleanout may be under an access cover
marked with an "S" or "Sewer."
STEP 3: Draw an imaginary line between the two above points -
sewer laterals normally run in straight lines.
What to Plant, What Not to Plant
Once you've determined the general location of the lateral on your property, you should avoid planting - or maintaining - any plants, bushes or trees that are likely to grow into or otherwise
foul your lateral. For more information on where-to-plant considerations, visit the International Society of Arboriculture (ISA)'s Webpage, Avoiding Tree & Utility Conflicts, at
trees are good.
In addition to planting locations, the type of tree you plant is also important to preventing future
sewer problems. Depending on the species of tree involved, the "safe" distance from your lateral varies. For example, roots of some Poplar trees have been known to reach into sewer lines nearly 100 feet away.
Planting appropriate types of trees is of critical importance. Tree roots tend to grow toward sources of water - including sewer pipes. If you're making additions to your home's landscaping, you can save yourself
headaches and money by choosing trees with deeper root systems. In particular, avoid planting trees with shallow, spreading root systems near your lateral.
Tree roots, in many cases, mirror somewhat the tree's above-ground canopy, growing in a "pancake" several feet thick below the surface. But, some particularly ambitious trees can extend roots far beyond the
drip line, or limits of their canopies, as they pursue water sources. There are a number of "problem" trees that should be avoided if sewer laterals and other underground utilities are a concern. These include
poplars, willows, figs, rubber trees and large eucalyptus trees. Two of the more troublesome trees are the fruitless mulberry and the Modesto ash. For an extensive guide on tree selection, visit
Cal Poly's site and select "low" for "Root Damage Potential" along with the other tree attributes you seek.
More Sewer Smart Planting Tips
After you select a tree, follow proper planting procedures. Be sure to dig a deep enough hole, but not too deep. If your hole is too shallow, the tree's roots will be more likely to spread horizontally making it
more likely that they'll meet, and possibly penetrate, sewer pipes and other underground utilities.
However, if your hole is too deep, the tree's root crown will be buried and disease and decay may result. According to the ISA, "It's better to put a $100 tree in a $200 hole than to put a $200 tree in a $100 hole."
For more on tree planting, visit tree care.
Remember, there are other non-sewer reasons to plan before you plant. Trees in the wrong places can also wreak havoc with your homes foundation, driveways, sidewalks and other structures. A properly selected, and
planted, tree will be a beautiful and healthy addition to your home's landscaping and won't cause headaches -- or backups -- in the years ahead.
More Sewer Smart Planting Information
Your local nursery may also be a good source of planting information. For a list of nurseries and garden centers in the San Francisco Bay Area that are participating in the Be Sewer Smart program, visit the California
Association of Nurseries and Garden Centers at:
For more useful, local tree resources, visit the City of Oakland's Public Works Agency tree program at: .
Still more tree information can be obtained from the University of California Cooperative Extension program at: http://ucanr.org/ce.cfm
For more specific information on desirable and undesirable plantings in your community, contact your city's public works department or your local sanitary district.