If you have a main line clean out you have an additional way of verifying a sewer drain clog. Locate the clean out if you don’t already know where it is. Open the clean out by either unscrewing or pulling to remove the cap. Check the clean out for any waste or water that may be backing up there. You should not be able to see the water coming up the clean out pipe. If water is flowing up and out of the clean out or standing in the pipe this confirms that you have a main line sewer stoppage.
Once you have verified a sewer drain clog you can move on to clearing it. Clearing a sewer drain requires a sewer drain snake. You can either call a professional plumber or rent the machine and clear it yourself. Either way a sewer drain clog should be cleared as quickly as possible.