The answer to 'water line won't flush' is that there are several common causes, including a clogged drain line, a problem with the toilet's flushing mechanism, or a blockage in the main sewer line. Symptoms may include the toilet not flushing properly, water draining slowly, or a gurgling sound coming from the toilet.
For minor clogs, you may be able to fix the issue yourself using a plunger or a drain snake. However, if the problem persists or you suspect a more serious issue, it's best to call a professional plumber. They can diagnose the root cause and provide the appropriate solution, whether it's clearing a clogged line, repairing a faulty flushing mechanism, or addressing a problem with the main sewer line.