The lifespan of a water heater with no maintenance is approx. 7-10 years. Water heaters are designed to last 30-40 years. So you ask, why is the average lifespan 7-10 years?
The most important item that has to do with the longevity of a water heater is the anode rod. The anode rod is a magnesium rod that serves as the sacrificial lamb for the water heater. When you heat the water in a gas water heater, the minerals in the water solidify and fall to the bottom of the tank in the form of sediment. When the water heater heats the water at the bottom of the tank, the sediment absorbs the heat, causing overheating at the the bottom of the tank (also causing the water heater to run less efficiently). This causes the glass lining to crack and allows the water to attack the steel tank, which makes it rust and leak.
If you change your anode rod periodically every 3-5 years, depending on the hardness of your water, your water heater will last 30-40 years.
How do you know when to change the anode rod? If the anode rod is missing at least 4″ of the rod when you remove it, then it must be replaced.
Water heater manufacturers also recommend flushing them annually. The only problem with that, is that most water heaters come with a plastic drain down valve that has the opening the size of pen. The second problem is the dip tube, which is where the cold water enters the tank. The problem with most dip tubes is that they do not reach the bottom of the tank where all the sediment is. So how do you change these items to enhance the drain down procedure? You must remove the drain down valve and replace it with a full port ball valve, and install an extra long dip tube, which will allow you to properly flush the water heater. Once you take care of these items you are well on your way to making your water heater last the 30-40 years it really should.
Call for more information on extending the life of your water heater, or to schedule installation of a new style tankless water heater.