Estimating the Lifespan of a Water Heater

by Nick Gromicko and Barry Fowler
While the typical water heater has a lifespan of about 10 years,  careful consideration of the factors that pertain to its lifespan can  provide the InterNACHI home inspector and the homeowner with information about  the potential costs that would be incurred by replacing the water heater.  These factors include: correct installation; usage volume; construction quality;  and maintenance.

Correct Installation

A water heater should generally be installed upright. Installing a water  heater on its side will place  structural stress on it due to inadequate  support for the heater and its pipes, and may cause premature failure.

Water heaters should be installed in well-ventilated areas — not just for  fire safety requirements and nitrous-oxide buildup, but also because poor  ventilation can shorten the lifespan of the water heater.

A water heater should not be placed in an area susceptible to flood damage.  Water can rust out the exterior and pipes, decreasing the life expectancy  and efficiency of the unit.  A water heater is best placed in an  easily accessible area for maintenance.  It should also be readily visible  for fire and health-hazard requirements.

The inspector may wish to inquire as to whether the water heater was  installed professionally. Homeowners may install their own units to save money,  but the installation of a tankless gas water heater, for example, requires more  skill than the average DIY task.  In the case of the  owner-installed tankless gas water heater, the home inspector may want  to check the gas pipe work for leaks to determine whether there is adequate  ventilation.


The life expectancy of the water heater depends a great deal on the  volume of water used. Using large quantities of water means that the water  heater will have to work harder to heat the water. In addition, the greater the  volume of water, the greater the corrosive effect of the water will be.

Construction Quality of the Water Heater

As with most household systems and components, you get what you pay for in a  water heater. Cheaper models will generally have a shorter lifespan, while more  expensive models will generally last longer. A good indication of a water  heater’s construction quality is its warranty.  Longer warranties  naturally imply sounder construction. According to a 2007 Consumer Report that  deconstructed 18 different models of water heaters, it was determined that  models with longer warranties invariably were of superior manufacturing quality,  with nine- and 12-year models typically having larger or higher-wattage  heating elements, as well as thicker insulation. Models with larger heating  elements have a much better resistance to mineral buildup or scum.

Pay attention to the model’s features.  Porcelain casing, for example,  provides an additional layer of protection against rusting, and a greater level  of heat insulation. Some models come with a self-cleaning feature that flushes  the pipes of mineral deposits, which is an important consideration in the  unit’s lifespan.  Models with larger or thicker anodes are  better-equipped to fight corrosion.

Maintenance and Parts Replacement

The hardness of the water is another consideration when looking at estimating  the lifespan of a water heater.  In areas where there is a higher mineral  content to the water, water heaters have shorter lifespans than in other areas,  as mineral buildup reduces the units’ efficiency. Even in areas where the water  is softer, however, some mineral deposition is bound to occur.  A way to  counteract this mineral buildup is to periodically flush the water heater  system, which not only removes some of the buildup, but, in tank systems, the  process heats the water in the tank. Higher-end models typically come  equipped with a self-flushing feature.  In models for  which manual flushing is required, it is important not to damage the water  heater valve, which is usually made of plastic and is easy to break.

Although an older model may appear to be well-maintained, a question  arises:  Is the maintenance worth it? Warranties often exclude labor costs,  so a good rule to follow is that if the total repair cost per year is  greater than 10% of the cost of buying and installing a new water heater, it is  probably not worth replacing damaged parts.

It is debatable whether the cost in time and money of replacing the  sacrificial anode in a water heater is worth the benefit of prolonging the use  of the existing water heater by a couple of years. In the tricky  process of emptying the tank and replacing the anode, it is easy to damage the  unit, and, as some warranties can be voided by anode replacement, the cost  of future repairs or maintenance that might otherwise be covered must be  considered.

In summary, there is a variety of factors influencing the lifespan of  a water heater. Beyond the basic telltale signs, such as a leaky puddle  under the heater or cold showers in the morning that indicate that a  new water heater is probably in order, the homeowner should consider the age and  warranty of the model, and carefully weigh the cost-benefit of maintaining an  existing heater versus buying a new one.