How to Remove Sediments from a Water Heater
(updated 2017)


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How to remove sediments and mineral deposits from electric and gas water heaters. Find out what is the cause, about symptoms and how to troubleshoot to prevent the element failure, increase the performance and efficiency. Check out what is the best way to prevent the sediment build-up.

Where are sediments in water

Sediments and mineral deposits can be found in any water heater storage tank, no matter is it a newer model or an old one - at the bottom of the tank and especially when water is heated. The amount of deposits depends on the type of water, its hardness and does the self-cleaning system inside the tank exist or not.

Sediments are found in water in a solid shape, as sand or particles coming from the well or municipality system and which are not dissolved. Even pieces from the lime scale build up and rust.

Rust deposits, for example, are the result of the aggressive water action, when the tank starts corroding, due to lack or failed rust protective elements like anode rod or metal tank lining.

Sediment build-up - Problems and solutions

The sediments in the plumbing and water heaters will eventually cover the elements such as electric heating elements, gas burner, also clog the valves, faucet or reduce the water flow. All these problems can lead to lower efficiency and performance, reduced power output, even shorter element life; and are a good sign that the water heater needs flushing and draining.

In such cases, users will mostly complain that there is "no hot water", "not enough hot water", "water temperature fluctuates", "popping, rumbling or sizzling noise" and so on.

For example, popping or sizzling noise is coming when water is trapped under the lime scale, next to the heating elements.

Even if the noise disappears due to change in water scale structure, that doesn't mean that tank flushing is not necessary; be aware that tank or heating elements can fail.

Lime buildup increases when the water is heated; with an increased temperature and water hardness, higher usage and increased heating surface. Deliming is therefore a necessary operation that has to be included in the regular maintenance and service.

Sometimes, the problem with sediments is significant, making the tank hard or not even worth cleaning, so buying a new electric or gas appliance is the only option.

How to remove sediments and lime scale from a water heater

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When you hear the noise inside the heater, as mentioned above, you have to act. Deposits are often loose and they are easy to remove. If you wait longer, water scale can harden and make it tougher to remove.

One of the solutions to get rid of the sediments, such as lime scale, from the tank type heater, is to dissolve the residue with delimer like phosphoric acid or vinegar and flush it out. Vinegar, for example, can be poured in through the opening once you remove the anode rod for checking and replacing. Let the vinegar sits for several hours to dissolve the limescale, and then flush it out.

Manually scraping of some elements is another fix, but it is time consuming, it is hard to reach some parts and clean it in full.

Setting the hot water temperature lower can reduce formation of lime scale, while installing softener can greatly reduce the hardness of water, and the anode rod can be affected.

For all these reasons from above, prevention is the way to go. The preventive, regular maintenance includes flushing and draining operation. The procedure is described here in details, and it looks like this, in short:

  • Turn the electricity to the water heater OFF (especially if the water heater is electrical).
  • If it is a gas type water heater, turn the gas valve OFF or set it to "Pilot".
  • Turn the cold water OFF
  • Attach one side of the garden hose to the drain valve located at the bottom of the unit, and take the other side of the hose and terminate at the nearby safe drain location, such as floor drain or sump pump pit.
  • Open up the hot water tap to prevent vacuum buildup inside the tank while draining.
  • Open up the drain valve to drain the water from water heater.
  • If there are still sediments inside the tank (drained water is not clear), half-fill the tank with cold water and drain again. This way cold water will loosen up the rest of the sediments and the water stream will flush them out.

Tools that you need to do the job:

  • Garden hose
  • Socket wrench
  • Bucket
  • Teflon tape
  • Brush for scrubbing

Note: In a case of the electric water heaters, if the water is emptied from the tank and if the power is turned ON, the heating element is exposed to the air, which will eventually burn out the element. So turn the power OFF. Also, it is important to bleed out all the air from the tank, using the TPR valve and hot water tap. When the hot water tap is open, water should be running continuously.

Sediment build-up symptoms - Highlights

  • Not enough hot water - deposits in the tank form the insulating layer between the heating elements and water, decreasing the contact surface and heat transfer.
  • Noisy operation - sizzle, hiss are characteristic in electric water heater, while gas and oil fired units may rumble and pound.
  • Longer heating time.
  • Shortened heater life.
  • High operating costs are results of the increased energy consumption.

How some water heater manufacturers fix the sediment build-up problem

Below are the examples, how some big water heater manufacturers in North America, are fixing problems when the sediment and lime scale deposits occur in the tank.

DynaClean is the patented automatic cleaning system from AO Smith water heating company. Thanks to the dip tube cold water turbulence in the tank, sediments and lime build-up, accumulated from the hard water is significantly reduced.

Hydrojet Total Performance System is the patented system from Bradford White that fights mineral build-up in the tank while extending first hour delivery.

Everkleen Self-Cleaning System is Rheem's patented technology that uses high pressure spiraling stream.

All these self-cleaning systems are helping operating efficiency and extending the tank life, maintain high energy efficiency, maximizing the output while saving energy and money.

Note: In most cases, the manufacturer's warranty does not apply if there is a heater failure due to rust, scale and lime buildup and deposits.

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