On Tuesday, September 11, 2012 9:54:38 AM UTC-4, DerbyDad03 wrote:
I have a basement bathroom that is located at the very front of the house.. All of the fixtures are within a few feet of the last clean out before the main drain leaves my house. The house is about 50 feet from the town's sewer pipe. I came home from work last night (Monday) to find that the toilet had very little water in it. There was still some water in the toilet, but it was below the bottom of the bowl section. When I flushed it I could hear noise from the shower drain, so I turned on the shower and heard the shower trap filling up with water. Since I had used the toilet and shower that morning, whatever happened had happened during the work day. I should add that the town was at the neighbor's house on Sunday evening, apparently snaking their drain. Their house is downstream from mine. However, as I said, I used the bathroom Monday morning so I know the toilet and shower trap were full when I left for work. Could the town have come back on Monday and done something with the sewer that would have sucked the water out of my toilet and shower trap? Obviously I'll check when I get home tonight to see if it happened again, but I'm curious as to what might cause the toilet and trap to loose water. Thanks.

It would be an unusual event unless your waste system is not adequately vented. Is that bathroom traditionally vented or does it have a studor vent under the sink? Studor vents do stick when they get old. Usually they are easy to replace.