Signs Your Water Heater May Need Repaired or Replaced

Your water heater is one of the most important appliances in your home, supplying hot water for showers, laundry, dishes, and daily comfort. When it starts to fail, you are likely to notice right away. Recognizing the early warning signs of water heater problems can help you avoid unexpected breakdowns, water damage, and emergency replacement costs.


At JF Denney, we specialize in servicing and installing both traditional tank water heaters and high-efficiency tankless systems, including Rinnai tankless water heaters. Below are the most common signs your water heater may need either repaired by a professional or replaced.

Picture of a woman relaxing in a bath with a tankless water heater

Common Signs Your Water Heater Needs Attention

1. Inconsistent or Insufficient Hot Water

Running out of hot water faster than usual or experiencing sudden temperature fluctuations is one of the earliest warning signs.

Possible causes include:

  • Sediment buildup reducing tank capacity
  • Failing heating elements or gas burners
  • Mineral scale buildup inside tankless heat exchangers
  • Improper system sizing for household demand


If left unaddressed, these issues worsen and can shorten the life of your system.


2. Strange Noises Coming From the Unit

Unusual sounds are often a sign of internal stress.

  • Tank systems: Popping or rumbling noises usually indicate hardened sediment at the bottom of the tank, forcing the unit to work harder and overheat
  • Tankless systems: Clicking or whistling may point to scale buildup restricting water flow through the heat exchanger

These noises signal reduced efficiency and increased wear on internal components.


3. Discolored or Rusty Hot Water

If your hot water appears brown, red, or cloudy, corrosion may be occurring inside the system.

This can indicate:

  • A deteriorating anode rod
  • Rust forming inside a tank
  • Failing internal components

Rusty water is often a sign that a tank water heater is nearing the end of its usable life and may soon leak.


4. Water Leaks Around the Water Heater

Any moisture or pooling water around your unit should be taken seriously.

Leaks may be caused by:

  • Cracked or failing tank walls
  • Loose valves or fittings
  • Pressure relief valve issues
  • Internal seal failure

Tank leaks almost always require replacement, while some tankless leaks may be repairable if caught early.


5. Rising Energy Bills

An inefficient water heater has to work harder to deliver hot water, driving up utility costs.

Efficiency loss is often caused by:

  • Sediment buildup in tank heaters
  • Scale-covered heat exchangers in tankless systems
  • Aging or worn heating components

A sudden increase in energy bills without increased water usage is a strong indicator of system inefficiency.

Tank Vs. Tankless Water Heater

Signs For Tank and Tankless Water Heaters

Signs Specific to Tank Water Heaters

Frequent Hot Water Shortages

If your household size hasn’t changed but your hot water supply has decreased, sediment buildup may be reducing usable tank capacity or insulating the heating element from the water.


Visible Rust or Corrosion

Rust on the exterior of the tank, connections, or fittings often means internal corrosion has already begun. This is a major warning sign that failure may be imminent.


Signs Specific to Tankless Water Heaters

Error Codes or System Shutdowns

Tankless systems are highly efficient but require regular maintenance. Error codes may indicate:

  • Mineral scale buildup
  • Venting or airflow issues
  • Ignition or flame sensor problems
  • Inadequate gas or electrical supply

Ignoring error codes can lead to reduced performance or even complete shutdown.


Delayed Hot Water or Reduced Flow

If hot water takes longer to reach fixtures or pressure drops when hot water is running, internal scaling may be restricting water flow and heat transfer.

Steam from a shower

Repair or Replace? How to Decide

You may want to repair your water heater if:
  • The unit is relatively new
  • The issue is isolated and minor
  • Repairs are affordable and don't occur that often.
  • 
You may want to replace your water heater if:
  • The system is near or past its expected lifespan
  • Repairs are becoming frequent and expensive
  • Energy efficiency has significantly declined, raising energy bills
  • The tank is leaking
  • You just want a newer, more efficient system.


Replacing an outdated unit with a modern high-efficiency or tankless system can significantly reduce energy usage and improve long-term reliability.

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Why You Should Choose JF Denney

For more than 60 Years, JF Denney has been a top leader in plumbing and HVAC in the Kansas City Area. Being a family-owned and local company, we are committed to sending our trustworthy technicians to provide top-notch service to our customers and saving them money where it counts the most. Contact JF Denney for all of your plumbing and HVAC needs -- We work hard to earn your referral!