Water Heater Failure
Signs, Causes, and Solutions

Fix a water heater that is not workingImage by Steve Buissinne from Pixabay

Explore early water heater failure signs and causes and see what you can do to prevent, fix, and protect the heating system. 

Extend the water heater's life and avoid cold showers by eliminating the problems related to thermal expansion, undersized tank, sediment deposits, and deteriorated anode rod.

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It is good to know that a water heater failure and unit replacement can be easily avoided if you identify the early signs of the problem. The symptoms or signs, potential issues, and how to troubleshoot them are described below. Some of these problems are easy to fix, and some require more time, knowledge, proper skills, and the right tools.

Note: For the correct, fast and safe repair of the broken water heater, the recommendation is to contact a professional plumber.

Common causes of the premature water heater failure

Thermal expansion

The thermal expansion occurs when the water temperature inside the water heating system rises, so the water expands and volume increases. Extremely high temperatures and pressure values inside the water heater tank can cause the leaky TPR valve, bulging heater, and deformations.

Water tank heaters are designed to withstand an internal pressure of up to 300 psi, but if the pressure exceeds this value, bulging will occur, followed by the deformation of the tank and its elements (such as nipples, flue tube) or rupture of the welds and joints.

The fix for the extremely high thermal expansion is installing the correctly sized expansion tank, which will maintain constant and safe water pressure. Such small expansion vessels are mandatory for heaters installed in the closed systems. If not, the manufacturer has the right to void the warranty. To avoid failure, make sure that the supply water pressure does not exceed 60 psi, otherwise, a pressure reducing valve is recommended.

Undersized water heater

The improperly sized water heater is usually the primary cause of the heavy condensation and rusting, including premature heater failure.

Condensation is normal, but heavy condensation is not. An extensive condensation and acidic condensate dripping on the burner and other elements will cause corrosion, create leaks, affect the performance, and shorten the unit life.

The fix for this problem is to size the unit properly, including the right storage capacity and recovery rate. Read this guide to learn how properly to size a water heater properly.

Cathodic protection

Every water tank heater, either gas-powered or electric, is equipped with an anode rod. The anode is used to protect the metal tank from aggressive water heater conditions or corrosive action.

The current derived from this rod makes the inner metal tank surface cathodic, therefore, protecting it from the chemical reaction with water ions and rusting.

If the rod is depleted or removed, the steel tank won't have such protection (actually only the glass lining), and it will eventually corrode.

The regular maintenance which will include visual inspection, cleaning, and replacement, is recommended.

Mineral buildup

Hard water, which is found in almost any region, can cause heavy mineral deposits and sediment or limescale buildup on the heater's components.

Water softeners are often recommended to deal with such a problem, but it should be considered its detrimental effect on the anode rods. Due to the rapid anode consumption, the rod should be inspected more often.

Limescale and mineral deposits on the heater's components and bottom will definitely clog the narrow water passages and reduce heat transfer and efficiency.

Instead of using water softeners, it is recommended to regularly perform a deliming and flushing procedure to remove the mineral buildup and further water heater failure.


So, if your water heater gives you only cold water, not enough hot water, makes a strange noise, water is discolored or has a weird taste and smell, it might be failing, nearing the end of its life, or it just needs some care.

There are many reasons for premature water heater failure. We have explained only four as the most common ones. More is to be found in this troubleshooting guide.

So to keep the unit running correctly and perform as it should, clean and maintain your water heater regularly, as recommended by the experts and manufacturers.

Don’t wait until it starts giving you a headache!

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