How do I know my A.O. Smith, Bradford White, Rheem, or State water heater is bad?

There are usually tall tell signs of a bad water heater.  Rust and corrosion are the obvious tall tell signs of your A.O. Smith, State, or Bradford White water heaters going bad.  Rheem makes a decent tanked water heater as well.  In Utah, the average life expectancy is in-between 6-10 years depending on how hard the water is and of course, usage.  I've posted a picture of a water heater that is bad, but it has the obvious signs.    If it is leaking on top, make sure the leak is coming from the water heater, and not the unions and/or other joints and/or shutoff valves from above the A.O. Smith, State, Bradford White, or Rheem water heater.  Most of the time my clients and others come home to a flooded basement.  Easiest prevention:  Water alarms, and water alarms are available at http://www.homedepot.com/, http://www.lowes.com/, and other fine retailers.  In certain states, the homeowner is allowed to change out the water heater, but you will will have to check city, county, municipality, state, and federal codes, and in that order.  Most codes require a licensed plumber to change out a water.  Check plumbers out on better business bureau, Angie's list, and other local consumer agencies.  Check out http://www.pondsutah.com/ for Utah residents.  Thanks for looking!