Finding the right water heater among all the various options can seem like a difficult task. The two most important features one should look for while buying a water heater are durability and energy efficiency. The material and coating of your water heater storage tank directly affect both aspects.

This post will clear all your doubts about the coating and material of the storage tank.

Need and Importance of Coating in Water Heaters

Water heaters are designed to retain hot water for some specific time, which in return increases the chances of corrosion in the tanks. In order to prevent the chances of corrosion, various kinds of anti-corrosive materials are used for coating the inner walls of the water tanks. This is the main reason why coating is essential.

The water storage tank is the most important part of any water heater. While buying your water heater, you should always check out the material of the storage tank and the kind of anti-corrosive coating.

Materials Used to Make Storage Tanks

There are three types of materials that are usually used for making the storage tanks of the water heaters. They are:

  • Copper – It is a good conductor of heat and therefore results in higher heat loss. It is also prone to corrosion.
  • Stainless Steel – Compared to Copper, stainless steel is a better option as it provides greater insulation. But it has the same issue of being prone to corrosion.
  • Thermoplastic – This material is not prone to corrosion as compared to both copper and stainless steel, but it lacks in the field of providing good insulation.

In keeping the aspect of insulation and corrosion in mind, the conclusion can be drawn that stainless steel tanks are the right choice. When provided with a layer of protection for corrosion, a stainless steel tank can serve its purpose for prolonged periods of time.

Types of Corrosion Protection Coatings

Various brands use various names for referring to the coating which creates a lot of confusion. It is quite easy to come across two identical products marketed with two different names of coatings. It is mainly done for advertising and marketing purposes, to provide customers with innumerable choices.

We have analyzed all the leading brands of water heaters in India and the different types of coatings that we have come across are:

  • Porcelain enamel glass lined tank
  • Glasslined coated tank
  • Vitreous enamel coated tank
  • Blue silicon enamel coated tank
  • Polymer coated tank

All these different types of corrosion protection are used for the same purpose and various brands use among these coatings for the multiple products.

The first 4 types of coatings use glass in one way or the other. The process of using glass as a coating material is a bit of a complex one. Glass is applied as a powdered substance on the lining of the storage tanks, and when heated at a certain temperature, the powdered glass fuses with metal to give an anti-corrosive coating.

As glass itself is a poor conductor of heat, the only way to attain the required anti-corrosiveness is to fuse it with stainless steel.

On the other hand, the polymers are quite different as they are synthetic in nature. In order to apply them as a coating, you have to use it as paint on the inner walls of the storage tanks.

Keeping the popular practices in mind, it is found that the glass is used significantly more than polymer coatings, but both of them have their drawbacks. So it can be said that theoretically, polymers have better efficiency, but practically glass is widely used as a coating material.


It can be concluded as the water heater which you are going to purchase should have better insulation capabilities with a higher grade anti-corrosive coating inside. The best water heaters generally use a stainless steel storage tank with glass or polymer anti-corrosive coatings.

Look out for the five star rated products as they are more energy-efficient as compared to the other lower-rated water heaters.

Most of the water heater brands offer a different warranty on the overall product and the storage tank. The warranty period is a good indicator of how durable the storage tank is. Water heaters that feature storage tanks with better corrosion protection will generally have a longer warranty period. Therefore, you should always check both the overall warranty and the warranty of the storage tank before buying a water heater.

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Buying Made Easy. Mr10 India