Question: What types of trees are least likely to plug my sewer lines with their roots?

Answer: Modern sewer lines don’t have the joints that old tile lines had. As a result, it’s not very likely that any tree’s roots will invade your sewer line. That changes, of course, if you’re out in the country, with lateral lines running out from a septic system. In those situations, you should probably choose a slow- or moderate-growing tree, and plant it 15 feet or farther away from the lateral lines. They should be deep enough that the roots won’t invade anyway.