If you've got a sewer line failure, the list of likely causes isn't very long. Sewer line failures aren't all that common, and when they do occur, there usually is a pretty specific reason. Tree roots If you have trees on your property, your sewer line may be at risk of being infiltrated by the roots. Tree roots can grow out several feet in all directions in search of a source of water, and your sewer line can provide it. If tree roots grow into your sewer line they can block it and cause leaks; either one of those things can cause a failure. Obstructions Anything you put down your drains can eventually cause an obstruction in your sewer line. Excessive food, grease and paper products not meant to be flushed can all get lodged in your line and create and obstruction over time that will cause your sewer line to fail. Old age Sewer lines can fail simply because of advanced age. After decades of being exposed to harsh conditions both inside the pipe and out, the line can simply crack or break and cause you a world of hurt. An inspection can tell you what shape your sewer line is in.