My sewer service line backs up about once or twice a year. When the plumber comes to unblock it, he finds tree roots in the line. The thing is, the only tree that has grown over the line was cut down at least eight years ago, before I moved into the house. The stump has been ground out and there is no evidence above ground that there was a tree there.

The plumber says this is not unusual for the roots of a tree to keep growing after the tree is removed, but he hadn't seen one last that long. Cleaning up after a backup is a pain, so I'm wondering if there's anything else that can be done to ameliorate the situation, short of replacing the line or digging up the yard in search of these roots.

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    Tree roots can apparently spread as much as 2-7 times the canopy size, or even 18 times the diameter of the trunk (eg: a tree with 6-inch trunk could have roots 19 feet away). [Source] Do you have other trees within range? If it is in fact roots, it does of course mean there is a leak in your sewer line..
    – gregmac
    Nov 22, 2016 at 16:27
  • @gregmac: there is a tree with a 18-inch trunk diameter probably 30 feet away. So that could be it. Nov 22, 2016 at 17:06
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    @gregmac the tree roots probably plugged the leak (just couldn't resist that) + for good information. Willow trees are horrible and may be able to go further. Ask your plumber how far out the main clog is, you may be able to dig down to that location and cut the roots back seal the hole and dump rock salt in the area will keep the roots from coming back for years without affecting surface plants.
    – Ed Beal
    Nov 22, 2016 at 19:59
  • Flush a cup of pure copper sulfate crystals down the toilet as your leaving for the day for 2 weeks, then repeat once a week until you dig the pipe up and fix it properly.
    – Tyson
    Nov 22, 2016 at 21:52


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