Tree roots may cause your sewer line to back up, sending
raw sewage into the house. If they grow big enough, they
may rupture sewer lines, meaning a lot of expensive and
messy clean-up work. Old houses are notorious for
problems with tree roots in sewer lines because the old
sewage pipes were made of clay and joined together with
mortar. Aside from the fact that we've all seen what
moisture does to compounds made of cement, mortar
crumbles over time. When a thirsty tree sends out its
tiny roots in search of liquid and organic nutrients,
the cracks in the mortar between the old cement sewage
pipes make a perfect entry point for small rootlets.
Even this wouldn't be a big problem, except for the fact
that as the roots find what they seek in the way of
moisture and nutrition, they start to grow and grow.
Eventually, there are big roots in the sewer.
comes to having tree roots in your sewer line, you don't
have too many effective choices. There are some products
that you can put down the toilet, which claim to kill
tree roots in sewage lines, but they often don't take
care of the problem adequately, and you can wind up with
worse problems than before. The problem with these
products is that sewer lines are rarely actually full:
the sewage tends to rest in the bottom part of the line.
For tree roots to be affected by chemicals in the sewer
line, they would have to be immersed in them: otherwise,
the ends of their rootlets may get burned (if they hang
down far enough), but the main part of the root may stay
above the remedy. The tree continues to prosper.
The best way to stop the roots that have joined the
sewer is to convince them to go elsewhere by using
copper sulfate in the soil around the sewer line. Trees
hate copper sulfate, but homeowners live the stuff,
because it may be all that stands between them and
paying for a brand new sewer system.
The hardest part of using copper sulfate is in
figuring out where your sewer lines actually lie. Not
only do you need an accurate idea of where each line is,
you also need to know the depth of the line at the point
or points most likely invaded by tree roots. If your
house is on a city sewer line, you can go to the city
office and find exactly where your sewer tap is, and
then trace the line (usually coming off the main at a 90
degree angle) back to your house. An even better option
is to hire a sewer company that uses an endoscope type
camera. They send the camera into the line and map the
exact line for you, including the precise location of
tree roots in the line. Electronics have also made it
possible for sewer companies to tell you the depth of
the line at any point along the way.
Once you have the information on location and depth
of the sewer line where the roots are, you can use an
earth auger to drill a 2.5 inch diameter hole in the
ground above where the roots are in the sewer line.
First, make sure there are no other utility lines where
you plan to drill—call the electric, gas and cable
company to make sure you have a free and safe access.
You'll also want one or more lengths of 1.5 inch PVC
pipe and a means of cutting it to the right length. You
will drill straight down toward the sewer pipe, stopping
when you get to a place 24-30 inches above the sewer
line. You don't want to go too far down, because the
solution you're going to pour into the PVC pipe should
go into the soil above the sewer line. Cut the pipe to
the length of the hole, and attach a threaded female
adapter with a plug onto one end of the pipe. Once you
have the hole drilled, put the pipe into the hole, and
if it needs trimming to lie flush with the ground (and
below the grass so you can't run over it with the lawn
mower), pull it out again and cut a little off the
bottom until it fits just right. If you have a lot of
roots in the lines, or a root that extends a long way
through or near a line, you will probably want to insert
a PVC pipe at each trouble point and every 6 feet or so
along the line of trouble.
Now comes the big fun: take off the plug at the end,
and pour copper sulfate into the pipe until it's about
half full of the crystals. You can buy copper sulfate at
feed stores, nurseries and some old fashioned hardware
stores. When the PVC pipe is half full, pour hot water
into the pipe until it tops up and runs over a little
bit. The copper sulfate is dissolved in the hot water,
and starts to run into the soil around the ground. Tree
roots hate copper sulfate, and will turn away. The ones
in the sewer line will die.
Whenever you do something that's not easily seen,
such as putting pipes into the ground around your home,
you can save yourself a lot of trouble later on by
creating a record of the work you did. Use a camera, GPS
or a hand made map to accurately show where you put the
PVC pipes in your ground. Who knows, you may need to
install sprinklers some day, or you may want to add
pipes to counter other root systems: it's important to
know where things are laid. Put the map with your other
important household maintenance papers so you never have
to hunt for it.
The copper sulfate solution works, but it's not a one
shot deal. You need to reapply the copper sulfate every
four months, or the copper sulfate will leach out of the
soil and the trees will send new roots to the sewer.
Make applying copper sulfate solution part of your
regular routine—once a season, to keep the roots away.
Copper sulfate is a great solution for deterring tree
roots, but it's not an overnight one. It takes months
for trees to get into the sewer, and it takes months to
turn them back from it as well. You have to wait for the
copper sulfate to take effect on the trees, and that
will take some time. But it works, so it's worth the