Water Heater Sediment Problem and How to Fix it

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Water heater sediment and limescale buildup - troubleshooting guide and preventing tips. What causes sedimentation, symptoms, and how to fix the problem. Is flushing enough? Find out how water heaters, when free of mineral deposits, perform better, have higher efficiency, save energy, and last longer.

What is the water heater sediment?

Water heater sediments are tiny solid particles coming from the sand, clay, or any other debris, and since they don't dissolve in water, they settle at the bottom of the water heater. Sediment build from minerals is present in any water type, either municipal or well.

Mineral deposits such as the limescale are also found on dishes, sinks, and bathtubs. This problem is present, more or less, in any home.

One of the main reasons for the sediment buildup is the hard water, which is rich in minerals, such as calcium and magnesium. This "problem" does not represent a health hazard, but it can severely affect your heater if accumulated beyond repair. Keep in mind that sediment may contain impurities that could lead to bacteria development.

How sediment can harm a water heater – problems, symptoms, and solutions

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Water heater sediments can affect both electric and gas-powered tank and tankless devices by reducing the energy efficiency, heating performance, and clogging the water pathway. 

If the heater is not maintained correctly, regularly, and per the manufacturer's instructions, water won't be heated, and you will not have enough water due to the reduced flow. 

In cases where the sedimentation is severe, there will be less room for the water so that you will be running out of hot water fast. The tank in such case is not worth cleaning, so it is better to buy a new unit. 

Popping noise occurs when water is trapped under the lime deposits. Sizzling or hissing sound happens when water is boiling to steam underneath the heating elements.

The temperature of water stored inside the tank fluctuates from hot to lukewarm, affecting user's comfort.

Sediment build-up might cause a relief valve to drip. The solution is to drain a heater, clean and tighten the TPR valve connection. If this cannot help, do not try to repair the valve – this is a safety device, and it must be replaced.

If you haven't flushed a water heater for a long time, a drain valve can also clog, prevent draining and closing, and resulting in an element leak.

Surfaces that are covered with limescale and exposed to heat could become hotter than if they were clean. As the gas burner cycles ON and OFF, these surfaces and connections will be exposed to rapid expansion and contraction, which can result in cracks and cause premature failure. The extreme temperature could even damage the tank's lining.

The presence of water heater sediments can cause changes 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 can create an insulating layer between the heat source and water, leading to insufficient supply and slow recovery. Over time, this problem can result in dry-fired heating elements. As the lower heating element cycles more often than the upper element, it collects sediments faster and fails more often. This is why Incoloy elements are what you should buy and install, as they will last longer than the components made of copper.

In tankless heaters, a heat exchanger is small, and water passages are narrow, so if it becomes clogged due to deposits, the water flow gets reduced, resulting in high temperatures, hot spots, and premature element failure. Flushing a tankless requires a pump to circulate the water through the heater. The flushing process is different from the tank type.

How to prevent and eliminate the sediment build-up problem

You have several options on how to deal with hard water and sediments.

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Install a water softener

The softener can help you reduce the deposits, but soft water can affect other elements, such as the anode rod, to accelerate the anode consumption. Using the water softener, you should inspect the anode rod more often and replace it when needed.

Install a filtration system

Installation of the whole house water filtration system is another system that helps reduce mineral deposits that are entering the home plumbing from the municipal water system or wells.


Buy a deliming solution from the manufacturer and treat the affected heater as part of the regular maintenance.

Flushing a water heater is probably the most popular choice for cleaning the tank and removing the sediments (if the tank is not affected severely). The idea is to weaken the deposits and flush the buildup out so the tank and water lines become clean. Vinegar can also be used for cleaning the tank, including soaking the elements.

Maintain temperature

Water heaters are mostly shipped to their new owners with the thermostat set to 120-125 F. Keep it that way because the higher temperature can cause scalding burns much faster, and more minerals can be left behind as sediment buildup. So, the hotter the water, is more deposits form on the elements.

Buy a water heater with the self-cleaning system

The recommendation is to look for models that incorporate a system that fights the water heater sediment and lime buildup.

The idea is 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 or slows down calcification.

Different manufacturers have different systems; Bradford White has the HydroJet Total Performance System; AO Smith DynaClean and Rheem have the EverKleen system. All these systems can reduce sedimentation problems with great success.

Instructions on how to remove sediments

  • Turn off the gas supply on the main gas valve or unit's gas control valve.
  • Turn off the electricity to a water heater on the breaker switch.
  • Open the hot water tap for a few minutes to release a few gallons from the tank, and reduce the hot water temperature, as it might be scalding.
  • Turn off the cold water supply on the main shut-off valve near the tank.
  • Locate the drain valve at the bottom of the heater, connect one end of the garden hose to the valve and get the other end to the nearest drain or outside the house. To speed up the process, you can use a drain pump.
  • Open a hot water tap (this is recommended to relieve the pressure in the system and make the water drain quicker). You can also leave the TPR valve open.
  • Open the drain valve to drain all the water from the tank. If you see small or large white particles coming out, this is the sign of calcium or mineral deposits. Once the tank is empty, close the drain valve.
  • Remove the cold water inlet pipe (anode rod or TPR valve) from the top of the heater. Take a funnel and pour a gallon of household vinegar. Let it stay for several hours. Vinegar should dissolve the buildup.
  • Put the inlet pipe (or whatever element you removed) back in.
  • Open the cold water supply valve. As the water starts coming in, it will stir up the sediments at the bottom. Fill the tank halfway.
  • Open the drain valve to flush the tank. The hot water faucet should also be open.
  • Repeat the flushing process until the water runs clear.
  • Close the drain and TPR valve, and remove the garden hose.
  • Turn on the water supply and refill the tank until full.
  • Resume the power.

Note: When the tank is empty, take the opportunity to check the anode rod, dip tube, and T&P valve, clean or replace if needed. If you need help to remove sediments, contact a plumber.

Required tools

  • Adjustable wrench
  • Plumbing wrench
  • Pliers
  • Garden house
  • Bucket
  • Funnel

A small amount of mineral deposits at the bottom of the water heater is not dangerous, while larger amounts can cause many problems. If you live in an area with hard water, sediment buildup can accumulate fast and calcify, making it difficult to remove. That is why regular maintenance is recommended.

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