They just don't make 'em like they used to.
No, seriously...they don't. Water Heaters used to be made durable and long lasting than thier modern counterparts, but today, if your water heater is over 10 years old, it's time to change it. If it's 10 years old, you're running on borrowed time.
The water tank inside the heater can bow out and dump hundreds of gallons of water into your basement in a matter of minutes.
While they may not be as durable as they used to, modern water heaters are A LOT more heat and energy efficient, and the higher efficiency, the more you save over time. Bradford white's water heaters are some of the best efficient appliances on the market. See for your- self: http://www.bradfordwhite.com/energy-efficiency-ratings
You can do some simple checks on your own to gauge if you should call in a service professional. Check all water connections coming into your water heater. Do you see corrosion or rust? Those bad rusty connection are causing more than one potential problem. First, rust particles are making thier way little by little into your potable water. That's not something you want to be drinking day after day. Also, there is about 80 pounds of pressure per square inch behind those connections. Once rust starts, theres no stopping it.
How about the general shape of you water heater? Do you notice and bowing out of the sides? An expanding tank is a good indicator that your water heater needs to go. If the tank splits, you're redoing your entire basement,
And one more tip for you: don't buy your heating appliances from chain home improvement stores. Call your service proffesional, go with a bradford white, and enjoy some peace of mind.