How Long Does a Water Heater Last?

Older Water Heater

Understanding the Lifespan of Water Heaters

The short answer to how long a water heater lasts is…it depends. The quality of the water heater and the water it is heating, the maintenance of the unit, and the installation all affect how long a water heater will generally last. Assuming the best of these factors, a tank water heater should generally last at least 8-10 years, while a tankless unit should generally last at least 15.

Tank Water Heaters: Maintenance Matters

Most professional-grade tank water heaters come with a six-year warranty on the tank. However, several factors can influence how long a water heater will last past that warranty. The quality of water plays a crucial role, as hard water can decrease a water heater’s lifespan due to sediment (calcium carbonate) buildup. Even without hard water, over time this mineral can accrue. This sediment acts as a barrier between the heat source—whether a flame in gas heaters or a heating element in electric heaters—and the water, thus reducing efficiency. A whole home water filter can help lengthen the life of your water heater and other fixtures in your home.

Regular maintenance, such as flushing the water heater, can significantly increase its life by removing the sediment buildup. Another issue that can shorten the life of a water heater is rust that can develop inside a tank. There’s an anode rod inside the tank designed to reduce this rusting process. A professional plumber can replace the anode rod, which helps prevent rust inside the water heater. Over time, if not replaced, the anode rod’s effectiveness diminishes, potentially leading to rust from the inside out.

The design of the water heater also matters. Non-professional grade water heaters often have plastic drains prone to leaking. Professional-grade models, which only professional plumbers can purchase, typically feature more durable brass drains. The frequency of use also impacts the heater’s durability, with those catering to higher demands wearing out more quickly. Despite these variables, as a master plumber, I generally see tank water heaters last between 8 to 10 years, though some can last over 20 years with proper care.

Tankless Water Heaters: Installation and Upkeep

Moving to tankless water heaters, these units tend to last much longer than their tank counterparts, provided they are properly installed and maintained. Tankless units come with longer warranties, sometimes up to 15 years on the heat exchanger. Without regular flushing, scale can build up inside a tankless unit, decreasing its efficiency and compromising the integrity of internal components. Because of this, manufacturers of tankless water heaters often require these systems to be flushed annually to maintain their warranties. Some manufacturers allow for longer intervals, like flushing once every 3 years, if a whole home water filtration system is installed. This is another example of how the quality of the water inside a water heater can affect its lifespan.

If a tankless unit is not installed correctly, the life of the tankless will be drastically shortened. The highly efficient operation of tankless water heaters creates acidic condensation that can lead to corrosion if the drain and vent piping are not properly installed. It’s important to hire a professional plumber who is specifically certified in the tankless brand being installed to ensure a maximum lifespan on a tankless.

Most failures in tankless water heaters that I encounter are not due to wear from use but rather from inadequate maintenance or improper installation. With proper installation and regular care, a well-maintained tankless water heater from a reputable brand, such as Navien or Rinnai, is expected to last at least 15 years.

Quality Product, Quality Install, Clean Water and Regular Maintenance

When hoping to get the full expected life of a water heater, you have to start with a quality, professional grade product. AO Smith tank water heaters and Navien tankless water heaters have an excellent track record for quality. A well known brand will stand behind its products and will also have easy to find components should you need a repair. 

A high quality product will only be as good as its install. Water heaters can involve complicated venting and drainage. For safety and longevity, it’s important for the install to be code compliant. You can expect a good looking, code compliant water heater install from a professional, certified plumber (not a handyman!)

Filtering the water that your tank or tankless heats can also drastically lengthen the life of your water heater. Moreover, you’ll get peak performance from your unit, since scale and sediment won’t be standing between your water and your heat source.

Finally, regular maintenance is key to getting the full life from your water heater. Flushing your tank or tankless will reduce build up and improve efficiency. A professional plumber can do a check up on your water heater during your flush to ensure that it hasn’t been throwing any error codes, that the pressure on your system is within a healthy range, and that there are no other plumbing issues with your system. 

To get help lengthening the life of your water heater, contact the Aaron Services team of professionals today.