Tankless water heaters are known for their better performance and long life expectancy. The foremost thing that arose into our mind while purchasing them is the “period of the lifespan.” 

A tankless water heater’s average life span is somewhere from 18 to 20 years. The life expectancy actually depends on various factors, including the water quality, i.e., hard or soft.

A gas-burning tankless water heater can last for 20 years with good maintenance. The life expectancy of a hot water electric tankless heater is between 8 to 11 years.

This article will provide a complete guide on their water heater lifespan, a rundown on what’s cutting the duration, and tips on making it last longer.

Expected Life of a Tankless Water Heater.

Many manufacturers don’t give a guarantee over 10 years. But, the average expected life is 18 to 20 years. It can be increased by flushing them regularly.

Type of Tankless Water HeaterAverage Life Expectancy with Good Maintenance
Runs on Gas20 Years
Electric Consumption11-12 Years
Heats up the Hard Water Quality15 Years
Heats up the Soft Water20 Years

How Long Does an Electric Tankless Heater Last?

They have a shorter life expectancy as compared to gas water heaters. It works properly for eight years. An annual maintenance check can increase the lifespan up to 11 years. 

What is the Life Expectancy of a Gas Tankless Water Heater?

A tankless water heater that operates on gas typically lasts for 20 years. Such a long life can only be expected with proper flushing of the system. 

What is the Expected Life of a Tankless Water Heater with Hard Water?

Overall, 85% of the U.S has hard water. Such water quality can cut the timespan of appliances. A tankless water heater lasts only 12-15 years with hard water. 

How to Increase the Lifespan of Tankless Hot Water Heaters?

Over time due to heat, minerals in water can build up and rot the walls of the heating unit.


These can cause uneven heating and disturb the system. The Longevity of Tankless Water Heaters can be extended in two ways;

1. Annual flushing

The overall performance and health of the heating unit must be flush annually. Flushing over a year costs around $150.

Why is it Important to Flush the Tankless Water Heater Once a Year?

There are several benefits of it. It impacts the performance and enhances the working quality.

  1. Reduce the repairs.
  2. Ensure the unit’s longevity.
  3. Minimize the effect of scaling
  4. It helps to improve the heat speed
  5. Noise reduction
  6. No obstructed pipes and clogs

2. Regular Descaling 

How to Descale a Tankless Hot Water Heater?


3. Required Equipment and Products.

  • Four gallons of white or regular vinegar.
  • Two drain hoses.
  • Large bucket (preferably 5 gallons)
  • Descaling Pump.

4. Steps for Descaling.

Descaling is a critical yet time-taking task. We have jumbled down the whole process into seven easy steps.

  1. Cut the power carefully.
  2. Shut off the water valves.
  3. Attach the hoses to input and output valves. In Bucket, put the other end of the hose.
  4. Fill the bucket with vinegar or other descaling solution. Then, place the pump into the bucket.
  5. Open the hot water valve and turn on the pump with care. Let the pump run for 45 minutes.
  6. Resin the water heater thoroughly.
  7. Disconnect the hoses and turn the water heater on by attaching the regular fixtures.

Tips and Cautions on Tankless Water Heater.

As a daily use item. We may overuse them often. It is essential to know and operate them as per the user manual.

How to Know that Your Tankless Water Heater is Going Bad?

Here are the six common signs.

  1. It has passed the warranty years.
  2. You notice some water heater leaks.
  3. Dirty or discolored water.
  4. It is making noises.
  5. Slow or not enough hot water.
  6. Required constant repairs.

If you noticed 3 out of these signs, you might need professional help. Or, it’s time to replace the tankless water heater.


With proper maintenance and annual system flushing, a tankless water heater can last 20 years. Electric water heaters may be less costly, but they have less lifespan than gas-consuming water heaters.


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