If you notice any of the following signs, it may indicate your hot water heater is failing and will need to be repaired or replaced soon:
Decreased Hot Water Capacity
One of the most common signs of a failing hot water heater is a decrease in the amount of available hot water. If you find you run out of hot water more quickly, or you aren’t getting as much hot water as before, it likely means your heater is having trouble heating up and maintaining temperature. As heaters age, mineral deposits accumulate inside the tank. This buildup insulates the water from the heating source, decreasing efficiency. If flushing the tank doesn’t restore full capacity, the heater may be nearing the end of its lifespan.
Longer Recovery Time
In addition to a decrease in available hot water, an aging heater will also have a longer recovery time. Recovery time is the period it takes for the heater to reheat the water in the tank to the set temperature after use. As efficiency drops, it takes longer for the water to reheat. If you’ve noticed it takes longer for hot water to return after showers or doing dishes, your heater may not be keeping up with demand.
Rusty Water
Rusty or discolored hot water is a sign of corroded internal tank walls. Water heaters contain an anode rod, designed to attract corrosion instead of the steel tank. As the anode rod corrodes over time, bits of metal can flake off into the water supply. Replacing the anode rod can temporarily help reduce rusty water issues, but a corroded tank often means the heater is nearing the end of its useful life.
Leaking Tanks
Once a hot water heater’s tank begins to leak, it’s time to replace the unit. A leak often starts small and worsens over time. Even a minor leak should be repaired immediately to prevent catastrophic tank failure. Watch for condensation or puddles under the tank, drips from pipes, or visible damp spots on the exterior as signs of a leak. A tank leak may begin rust-colored if it originates from corrosion inside the tank. Catching a leak promptly will help reduce water damage to your home.
Faulty Temperature Regulation
A hot water heater’s thermostat controls the internal temperature. If the thermostat fails, the tank may overheat or water temperature may fluctuate unexpectedly between very hot and lukewarm. First try adjusting the temperature dial to see if the issue persists. If adjusting the thermostat doesn’t help, or attempting to relight the pilot light doesn’t resolve temperature regulation problems, thermostat failure is the likely cause.
Pilot Light Won’t Stay Lit
Gas water heaters rely on a pilot light to ignite the burner. If the pilot light won’t stay lit, it could indicate an issue with the thermocouple. The thermocouple is responsible for sensing the pilot flame and signaling the gas valve to remain open. If the thermocouple malfunctions, the pilot will go out. First clean the thermocouple and retry lighting the pilot. If the problem persists, replace the faulty thermocouple.
Rumbling, Banging, or Percussive Sounds
Loud rumbling noises from the tank are usually due to sediment buildup inside the unit. As mineral deposits accumulate, they can cause the water to boil erratically, emitting rumbling noises. Sometimes air can become trapped inside the tank, also causing banging or percussive sounds as the air bubbles move about. Try flushing the tank or adjust the thermostat temperature to see if noises persist. If the sounds continue, sediment accumulation or a faulty heating element may be to blame.
Low Water Pressure
A drop in hot water pressure may indicate an obstruction in the hot water line or a problem with the heating elements. Clogged heating elements or mineral deposits inside valves and pipes can restrict water flow. Low water pressure coming only from hot water faucets points to a problem with the water heater rather than overall building water pressure. Inspect the hot water fixtures for blockages or leaks first. If no obstructions are found, a faulty heating element or sediment buildup is likely preventing proper water pressure.
Higher Energy Bills
As a water heater becomes less efficient, it requires more energy to heat the same amount of water. Unusually high energy bills, therefore, can indicate a failing unit. Energy costs typically rise gradually as heaters age, but a sudden spike may mean it’s time for a new one. Make sure to also check for other explanations like a gas leak, change in utility rates, or increased hot water usage before assuming the water heater is the sole culprit.
Burner Flame Appears Abnormal
The burner flame inside a natural gas water heater should appear blue with a hint of yellow near the tip. An orange-yellow flame or sooty, dark flames indicate combustion issues. Sediment buildup, faulty burners, or improper gas pressure could prevent the burner from firing correctly. Have a technician inspect the burner right away, as improper combustion can lead to a dangerous carbon monoxide leak.
Hot Exterior Surfaces
While the tank exterior does get warm to the touch, excessive heat on the outside of your water heater may signal a problem. If the external temperature is hot enough to burn you, the internal components are likely overheating. Faulty thermostats, aged insulation, or a defective heat trap in electric heaters can lead to overheating. Left unaddressed, overheating components drastically shorten the appliance’s lifespan.
Odd Smells
Unusual odors around the water heater may be caused by overheating electrical components or improperly combusting gas. A sulfurous rotten egg smell indicates a gas issue like incomplete combustion or a gas leak. Burning plastic gives off a distinctive fishy stench as internal parts melt and degrade. Smoke odors signal overheated wiring or other electrical components. Regardless of the odor, unusual smells warrant immediate appliance inspection by a professional.
Pool of Water Nearby
Finding a puddle of water on the floor near the hot water heater often signals a leak. However, condensation can also cause water to pool around the tank. As condensate forms on cool tank surfaces, it drips down the side. A water leak requires immediate repair. For simple condensation, improving air circulation around the unit can help diminish the problem.
Clanging Metal Expansion Noises
As water is heated, it naturally expands in volume. This expansion causes pressure changes within the tank that produce loud banging or clanging noises. The noise worsens over time as the tank weakens internally. Pressure fluctuations also accelerate corrosion and leaks. The periodic explosive noises indicate the tank walls can no longer properly handle thermal expansion. Replacing an aging, noisy tank helps prevent catastrophic rupture failures.
Cloudy/Discolored Water
White or brownish water is often caused by rusty internal components. Particles of sediment loosen over time and discolor the water. The cloudy water should clear after running the taps for a few minutes. If the discoloration persists or frequently returns, inspect the interior for corrosion. Cloudiness could also result from chemical reactions between certain types of piping and sulfate compounds in water supplies.
Hot Water Has Foul Smell or Taste
An unexpected rotten egg odor or sulfur smell in hot water usually stems from bacteria growth inside the tank or pipes. Water naturally contains hydrogen sulfide gases that bacteria feeding on sediment can produce. Foul tasting or smelly hot water poses no health hazards, but indicates the tank needs flushing. Shock chlorination paired with a tank flush can eliminate bacteria and improve water quality.
Significant Age
As a general rule of thumb, water heaters have a functional lifespan of 8-12 years. However, hard water, high usage, incorrect sizing, poor maintenance and other variables affect longevity. By around 10 years though, most heaters exhibit some signs of wear regardless of conditions. If your unit nears or exceeds 10 years, replacement may be prudent even without other symptoms. Preventative replacement avoids more costly emergency leaks and downtime.
Condensation Drips
Excessive condensation forming on the tank that drips or pools on the floor indicates improper ventilation. As hot humid air contacts the cool tank surface, it condenses into water droplets. Improper clearance around the tank prevents air circulation needed to dissipate this moisture. Excess condensation hastens corrosion and part failures. Improve ventilation or redirect humid air away from the tank to resolve excessive condensation.
Conclusion
Catching hot water heater problems early allows for less disruptive repairs and maintenance. Periodically inspect for leaks, odd noises, temperature fluctuations, decreased capacity, and other malfunctions. Most problems become worse over time if left unaddressed. At the first sign of deterioration, a few repairs and tank flush can often extend the appliance’s service life. But once major components fail, replacement is the only option. Knowing when to repair versus when to replace your old unit can prevent unexpected hot water outages and costly water damage in your home.
Warning Signs Quick Reference Table
| Issue | Possible Cause |
|---|---|
| Decreased hot water capacity | Mineral buildup insulating tank, reduced heating efficiency |
| Longer recovery period | Lower heating efficiency |
| Rust colored water | Corroded internal tank |
| Tank leaks | Corrosion, cracks, or ruptures in tank |
| Temperature fluctuations | Faulty thermostat |
| Pilot light won’t stay lit | Thermocouple issues |
| Loud rumbling noises | Sediment buildup in tank |
| Lower hot water pressure | Clogged heating elements or mineral deposits in pipes |
| Higher energy bills | Declining efficiency of aging unit |
| Abnormal burner flame | Sediment buildup, faulty burners, improper gas pressure |
| Hot exterior surfaces | Faulty thermostat, insufficient insulation, defective electrical components |
| Odd smells | Gas leaks, overheating components, electrical burns |
| Pool of water | Leaks or condensation |
| Clanging noises | Metal expansion from temperature fluctuations |
| Cloudy/discolored water | Rust particles from corroded interior |
| Smelly hot water | Bacteria growth inside tank and pipes |
| Age over 10 years | General lifespan of most water heaters |
| Excessive condensation | Lack of air circulation around tank |
Refer to this table for a quick overview of some of the most common signs of water heater failure, along with the typical causes behind each symptom. Keep an eye out for these issues in order to proactively monitor your appliance and prevent disruptive breakdowns.
