The answer to 'why is my sewer line no hot water' is that the issue is likely not related to the sewer line itself, but rather to the hot water heater or the plumbing system that supplies hot water to your home. Common causes can include a malfunctioning water heater, a blockage or leak in the hot water pipes, or a problem with the home's plumbing system.
If you're not getting any hot water at all, the first thing to check is the water heater. Make sure it's turned on and that the pilot light is lit. If the water heater is not functioning properly, you may need to call a professional plumber to diagnose and repair the issue. If the water heater seems to be working, the problem could be a blockage or leak in the hot water pipes. This may require more extensive plumbing work to locate and fix the issue.