My house's main drain line collapsed shortly after I returned from Africa. We suspect that with no one in the house, and hence no water running down the pipe, that the roots of my willow tree may have grown trying to find more water, weakening the pipe. At the end of day 2, we think there is a pipe break near the city sewer, so they are going to come back and do a 'pipe burst' replacement of the entire drain from my house to the street. It's a mess and it cost a fortune to fix. Here are some photos from the job. I had a 2 day hiring conference to attend so I'm sorry I don't have any pictures of the pipe burst.