To stop plumbing problems in their track before they progressively become worse, you should know what to look for:

  1. The handle of the toilet and the tank ball might be stuck together. 
  2. The flapper valve might be sticky or something is preventing it from completely closing after it is flushed. Cleaning or replacing the flapper valve could help the problem.
  3. The ballcock cannot close all the way and might cause the toilet to leak. 

Fixing these problems before they get worse will prevent future problems that are more serious. If you notice any of these problems, you should call a licensed plumber to solve them.