A standard water heater will last till eight to twelve years. Most of the tanks will eventually leak, in some cases have slow leak and some cases have more leaks. For this reason it is a good idea to know where your dedicated water shutoff valve is located. It is important to keep in mind, that although a water heater may be still working, most water heaters decrease in efficiency over time as sediment builds up inside the tank.

Tankless heaters can last two to three times longer than the traditional water heaters.
Here are few things that can extend the water heater’s life.

Second anode rod: The anode rod also known as sacrificial rod made of magnesium or aluminum, undergoes galvanic corrosion over time sacrificing itself and thereby preventing the corrosion of the tank. Second anode rod is useful in extending the life of the water heater.

Expansion tank: If you are in a closed system, installing an expansion tank can potentially double the life of water heater. When water is heated from 50º to 120º, the tank expands by approximately 2%. If your system is closed, this water has no where to go and because water is not a compressible material it will cause rapid increases and decreases in water pressure. This expanding and contracting causes stress on both your water heater and your plumbing system which can cause damage and premature failure.

Cleaning and flushing out your tank: For older tanks, flushing the tank annually can help to prevent sediment build up and maintain higher efficiency of your tank for longer time.

Installing a pressure regulating valve or PRV: If you have a very high water pressure above 90 PSI, your water pressures can damage your appliances and can also cause failure of your water heater. By installing pressure regulatory valve, system pressure is reduced, this also reduces your systems wear and tear on all your appliances.

Water softeners: In some areas, water has very high mineral contents. It results in hard water scaling which is a precipitation of minerals that deposit on the walls of the appliances. This can drastically reduce the life of the water heater. In many cases, installing the water softener can help reduce wear and tears on the plumbing system.

By following all the above ways you can extend your water heater’s life.