Invasion of the roots: Ficus tree causes sewer problems

When our front toilet began draining slower and slower, I knew there was a problem. I called Area Plumbing and Joe, the plumber, was sent out.

I explained the situation, he gave a knowing nod and told me that usually a ficus tree was the problem; but in our case, a large pine tree near the northeast corner of our house was probably the culprit. I was skeptical of his analysis. How could a tree cause sewer problems?

Joe removed the toilet and pointed to the gap between the sewer pipe and the floor tile.

“That gap is called the expansion gap. Do you see the dirt and those roots growing in the gap and the wax ring?” he asked. “There's your problem. The pine tree roots have traveled, looking for water, under the foundation and up beside the sewer pipe leading to the toilet. If you had waited a few more months to call me, those roots would have made their way even further into the toilet and blocked it completely.”

I was shocked. “What can be done to fix the problem?”

“Actually, there's an easy remedy,” Joe told me. “If I sprinkle copper sulfate crystals around the expansion gap, it will kill any roots and discourage new ones from growing. If I don't kill the roots, they will continue growing and will grow down the pipe. I've found roots six feet long or more growing inside a sewer pipe, blocking drainage completely.”

Joe poured copper sulfate around the extension gap, added a new wax ring and reseated the toilet.

“That should solve the problem for now,” Joe told me. He handed me a large plastic container and said, “Pour a capful of this product into each toilet monthly and it will help keep the roots killed.”

I was extremely happy the problem had been solved and the toilet was draining properly. If you have a slow flushing toilet, roots may be the cause of your problem.

Dave Faires, urban forestry supervisor for the city, stated that all trees have the potential to damage sewer lines, water lines and concrete foundations. Ficus and mulberry trees cause the most problems because they grow fast and have very invasive root systems. He recommended never planting a ficus or mulberry near a building or sidewalk.

When asked about the use of copper sulfate, Faires agreed that it would help with small root problems. However, if a pipe is cracked or damaged, roots will find the break and become invasive. He explained that only the removal of the tree and replacement of the damaged pipe would solve the problem.

When choosing trees for landscaping, remember that your small four-foot sapling will grow to a height of 20-30 feet. Its roots will extend as far out as the height of the mature tree; and in some instances, the roots will extend three or four times the height of the tree.

That means planting a tree eight feet away from your house is not a good idea. Instead of a tree, plant a shrub. As a fire precaution, the closest tip of any tree branch should be at least 30 feet away from the roof of the house.

A good rule of thumb is to plant trees a minimum of 40-60 feet away from the house. This will minimize roots invading the sewer lines or uprooting sidewalks and will keep the tree from becoming a fire hazard.

A few trees with more invasive roots are the California pepper tree, mesquite, cottonwood, poplar, weeping willow, eucalyptus, fig, fruitless mulberry, modesto ash, Arizona ash, ficus, Russian olive, honey locust and sissoo.

When planting any tree, carefully consider its size and the size of its root system at maturity. You don't want the tree to become an expensive problem because of being planted in a wrong location in your yard.

Karen Bowen is a Master Gardener and member of Yuma Garden Club. She can be reached at bowenkaren@ymail.com. This column is sponsored by the Federated Garden Clubs of Yuma.