There are a lot of things that you should factor in when trying to determine how long a water heater should last. Most of the new water heaters that we install come with a six year warranty. However we do offer tanks that are guaranteed for up to 12 years.
Of coarse this type of tank is going to cost more, partially because of the warranty itself.
The hardness of your water can also impact the life of your water heater. Hard water can definitely shorten the lifespan of your unit. However, some water softeners have also been know to shorten the lifespan of a water heater.
I have seen water heaters that have failed within the first year of being installed. Often, it is not the fault of the water heater but can also be caused from too much pressure in the plumbing system. If you are experiencing problems with your water pressure you should have a plumber test your water pressure. If your pressure reads over 100 psi then you should check for two things. The first is an expansion tank. An expansion tank is a device used to balance out the pressure in the plumbing system. It can protect your water heater as well as other fixtures in your home.
Another thing to look for if you pressure is too high is a PRV or pressure reducing valve. This device isn’t designed to give you bad water pressure, it still can allow from anywhere to 50-80 psi and can also be adjusted. If you do have a PRV installed and are still experiencing high water pressure, you may need this part replaced.