How to descale your electric water heater

How to descale your electric water heater

Sébastien, Rédacteur, Puy-de-Dôme

Guide written by:

Sébastien, Rédacteur, Puy-de-Dôme

316 guides

Descaling a storage water heater helps to extend the life of your heating element, slow down tank corrosion and decrease your electricity bill. You'll need to start by draining your hot water cylinder before removing limescale from all components. Read on for our step-by-step guide to descaling a hot water cylinder.

Important features

  • Draining the water heater
  • Removing the elements and anode rod
  • Descaling the tank
  • Replacing the access panel and reconnecting your water heater
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Why descale a hot water cylinder?

Descaling a how water cylinder, or storage water heater, will help to extend the service life of your heating element as well as the system as a whole. But it will also help you cut down on your electricity bill; an element covered with limescale will use up 10% more electricity than a clean one to produce the same amount of energy.
This process will also allow you to check the condition of your anode rod. In turn, this helps to prevent any corrosion of the tank which can happen when a sacrifical anode rod wears out without your knowledge.

Draining your storage water heater


The first step in descaling your water heater is to drain the cylinder to access the inner components. This is a straightforward process that can be planned out in advance to save you time and money. Start by cutting off the power and water supply to the water heater.
Next, turn on a hot water tap in the house to relieve the remaining pressure and open the drain valve using a hose or bucket to collect the water. To avoid wasting the hot water already in the tank, turn off the power supply and water supply the day before and use the remaining hot water to shower, take a bath and do the dishes!

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Removing the element and anode rod


The heating element and anode rod should be fixed to a cover that is usually shielded by an access panel; remove this using a screwdriver to unveil the thermostat wires. Once you have access to the inside of the cylinder, you can start to remove the sediment deposit from the bottom of the tank. Clean the heating element(s) with a mild limescale remover and/or brush it down with a wire brush, being careful not to damage the metal.


If your sacrifical anode rod is worn out, you will have to replace it. The impressed current anode rods and hybrid systems do not have to be replaced but they should be cleaned.

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Replacing the access panel and reconnecting your water heater


Once you have descaled the inside of the cylinder, cleaned the heating element(s) and swapped out your anode rod (if required), you can then start reassembling the components in the same order as before. Reconnect the wires and the plastic cover.


When all parts have been refitted properly, you can turn on your power and water supply, and enjoy hot water once again!


More information

For more information on water heaters, check out the following guides:

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Guide written by:

Sébastien, Rédacteur, Puy-de-Dôme, 316 guides

Sébastien, Rédacteur, Puy-de-Dôme

A l’issue d’études dans le commerce, j’ai appris par opportunité la profession de charpentier. Noble mais dur métier, les hivers et la pluie m’ont incité à descendre des toits et à pousser les portes d’une quincaillerie où sans grande surprise, je me suis retrouvé quincaillier. De vis en boulon, j’ai travaillé au fil des années dans tous les rayons de magasins de bricolage où j’ai eu le loisir d’apprendre l’utilité et le fonctionnement de tout ce qui s’y vendait. Entre deux magasins, je n’hésitais pas à travailler comme serrurier, couvreur, menuisier ou dans le secteur industriel. Mon expérience terrain conjuguée à mes connaissances techniques me permet de jauger le vrai du faux dans le choix des outils et équipements. Préférant restituer un conseil désintéressé à l’écrit que me répéter du lundi au samedi dans un magasin, il était naturel que je me dirige vers le métier de rédacteur.

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