There are many things that could mess up your plumbing, but the trees in your yard might not be the first thing to come to mind. However, many homeowners have experienced the trouble that trees can cause in the plumbing system. How can this happen? Well, the mixture of water and waste product that runs through your plumbing lines is a great fertilizer. A poorly sealed joint in your pipes, or a crack, would allow for a root to sneak its way through. This one root will then pry the pipe open as it grows, making room for more leakage and roots. Once you have a large amount of roots in your pipes, you will notice toilets and sinks backing up, sometimes in a catastrophic way.
Unfortunately, there is no quick and easy fix to this. While chemicals might kill off the roots, and cutting off the roots is another option, neither of these fixes are permanent. The best way to fix the problem once and for all is to dig up the pipe and replace the broken section.