Water Heater Sediment Problem and How to Fix it

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Water heater sediment and limescale build-up troubleshooting guide. What causes the sedimentation, symptoms and how to fix the problem. Find out how water heaters, free of mineral deposits, last longer, are more efficient and better performing.


Water heater sediment and lime-scale build-up are the same as mineral deposits you will find on dishes, sink or bathtubs. This problem is present, more or less, in any home. One of the main reasons for sediment build-up is the hard water, which is rich in calcium. This “problem” is not a health hazard for you and your family, but it can severely affect your heater.

Water heater sediments can affect both electric and gas powered tank and tanklessdevices by reducing the energy efficiency, heating performance and clogging the water pathway. If the heater is not maintained correctly, regularly and per manufacturer’ instructions the sediments might be so thick that would act as the insulator between the gas burner and water, so you will basically have no or reduced flow. In cases where the sedimentation is severe, the tank is not worth cleaning, so it is better to buy a new unit.

Problems associated with the mineral deposits

  • Noise – Popping noise occurs when water is trapped under the lime deposits. Sizzling or hissing noise happens when water is boiling to steam underneath the heating elements.
  • Sediment build-up might cause the relief valve dripping. The solution is to drain the heater and fix the TPR valve connection.
  • Surfaces covered by the limescale and exposed to heat become hotter than if they were clean. As the burner cycles ON and OFF, these surfaces and connections will be exposed to rapid expansion and contraction, which can result in cracks.
  • Excessive water heater sediments will cause the change in water color. Flush the unit periodically as part of the regular maintenance and if necessary, install the filter.
  • Clean the bottom of the tank and heating elements, as deposits might create a cushion between the heat source and water, which can lead to an insufficient supply and slow recovery. Over time, this problem can result in a dry fired heating element. As the lower heating element will cycle more often than the upper element, it will collect sediments faster and fail more often. This is why Incoloy elements are what you should look for in the electric models, as they will last longer than the elements made of copper.
  • In tankless heaters, a heat exchanger is small and if the water passages are clogged by the sediments and lime-scale build up this will reduce the flow and result in high temperatures.
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A solution for water heater sediment build-up

  • There are few solutions for hard water and sediments. One is to install a water softener. This is what can help you to reduce the deposits, but can affect other elements, such as the anode rod as it will accelerate the anode consumption. If using the water softener, you should inspect the anode rod more often and replace it when needed.
  • Another solution is to buy a deliming solution from the manufacturer and treat the affected heater as part of the regular maintenance.

The recommendation is to look for the manufacturer that incorporates a system that fights the water heater sediment and lime build-up. The idea is actually very simple. An innovative design of the dip tube ensures that the incoming water makes the turbulent flow inside the tank, which dissolves the calcium compounds. Different manufacturers have different systems; Bradford White has the HydroJet Total Performance System; AO Smith DynaClean and Rheem has the EverKleen system. All these systems are able to reduce the sedimentation problems with the great success.

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