State University Extension
Home Maintenance And Repair - 01500169
Fixing Main Drain Plugged with Roots
Sometimes the main drain from the house may be plugged with roots, or
the drain to the septic tank might be full; so first check to be sure
other drains in the house are clear. If other drains are plugged and
toilets don't flush, the problem is most likely in the main sewer
outside the house. Temporary repairs can be made by using a plumber's
tape, a 50' to 100' long strip of steel about 1" wide and 1/8" thick
with a point on the end.
Find a cleanout plug in the basement near the outside wall where the
drain goes out to the septic tank or street sewer. With a large wrench
remove the brass plug and start the point of the tape down the drain.
If the tape hits an obstacle, ram it back and forth until it clear.
When it clears you will probably hear the water gurgle as the pipe
empties. With a hose flush the drainpipe before replacing the plug.
If the stoppage feels like roots, then water draining slow and the
stoppage recurs frequently you might try copper sulfate to kill the
roots. The following steps should be followed.
1. Where stoppage is serious and recurrent, apply 5% copper sulfate
crystals, once a month until condition is much better. A drugstore or
chemical supply store has this material.
2. Follow this with one pound doses per year (mark on your calendar).
3. Don't allow copper sulfate to stand in fixture traps, as metal
corrosion may occur. Flush the crystals through toilet bowl or through
the cleanout in the basement and follow with enough water to insure
(a) their transmission through the soil pipe to beyond the cellar wall
(b) their conveyance to and against the root obstruction.
NOTE: The clean-out is not the drain where you dump laundry water. It
is the place where a cap must be removed to gain entrance to the drain.
4. Don't expect immediate results from copper sulfate; only the life of
the roots is taken by the copper treatment, and thereafter the normal
processes of decay must ensue before roots can be carried on out to the
5. Don't expect the treatment to clean sewers mechanically obstructed
by breakage, bad construction or foreign material.
When copper sulfate is used in connection with a septic tank tile
field, the solution could be poured into an opening in the tile line
beyond the tank itself. If you run the solution in the through the
septic tank it will be diluted and not clear a stoppage in the tile
field and might temporarily affect the bacterial action in the tank.
This article was written by Anne Field, Extension Specialist, Emeritus,
with references from Michigan Extension bulletin First
Aid for Plumbing.
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status. Issued in furtherance of MSU Extension work, acts of May 8 and
June 30, 1914, in cooperation with the U.S. Department of Agriculture.
Thomas G. Coon, Director, MSU Extension, East Lansing,MI 48824. This
information is for educational purposes only. Reference to commercial
products or trade names does not imply endorsement by MSU Extension or
bias against those not mentioned.
information.was reviewed as
of June 2008. For more information about the contents please
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