As warm water passes through sewer lines, a vapor forms on the exterior of the sewer pipe. The soil surrounding the sewer pipe absorbs the vapor moisture. Tree roots in the vicinity will grow toward the moist soil and may eventually enter the sewer line, where they can block the flow. You may avoid a hefty plumbing bill by using rock salt to not only get rid of tree roots, but to prevent new roots from taking over the sewer lines.
Pour a 4-pound box of rock salt down a toilet and flush. Pour the salt down the toilet in the evening before you and other household members go to bed, since the salt water should remain in the sewer line for at least eight hours. Do not use any other drains in the house to avoid diluting the salty water solution.
Flush the toilet again after eight hours. You may also resume use of any drain in the house after eight hours.
Repeat Steps 1 and 2 every month. Tree roots in the sewer line will eventually die from absorbing the sodium from the rock salt. Repeat the process monthly to keep the lines clear.