Chemicals used in cooling tower water treatment

In this article, we are going to learn what is cooling tower chemical dosing and what are Chemicals used in cooling tower water treatment along with the function.

Utilities are used in the chemical industry for maintaining process parameters and among those cooling water as a utility is widely used in almost any chemical industry. Cooling water quality is to be maintained as a disturbance in cooling water quality or parameters can affect various equipment and pipes.

We had covered cooling towers in detail such as types of cooling tower and we had also covered important terms related to cooling towers such as cooling tower approach and efficiency calculation.

Chemicals Used In Cooling Tower Water Treatment

To maintain the quality parameters of cooling tower water, different types of chemicals are dosed in it. These chemicals are used to treat cooling water so that it remains as productive for the equipment and pipes.

Prior to getting into what chemicals are used in the cooling towers, let us get a brief introduction on what is dosing, What is a Cooling Tower Water Treatment? and why to maintain cooling tower water quality and treat cooling tower water.

What is dosing?

Dosing refers to injection. In the chemical industry, chemical dosing pumps which are usually positive displacement pumps, are used to add chemicals to the process stream which are essential to the manufacturing process. A similar type of dosing pump is used in cooling towers to dose chemicals.

Now, that we had learned what is dosing, let us move forward with what are the cooling tower dosing chemical and what are the uses of those.

What is a chemical dosing system in a cooling tower?

In a cooling tower, maintaining water quality is crucial. To maintain cooling water parameters, chemicals are dosed which helps in maintaining cooling water parameters. the chemical dosing system in the cooling tower helps and protects the cooling tower from corrosion and also protects other equipment.

Chemicals used in cooling tower water treatment

Different chemical are use in cooling tower chemcial dosing to maintain the quality of water which ultimately improves the efficiency of the cooling tower and provids us the best possible result. Here are the chemical and their purpose in cooling water treatment.

pH Adjusters

Cooling tower water pH is maintained at 7.0 as neutral as highly acidic or basic water can damage cooling tower parts and also equipment in which that water is circulated in the system. As pH increase or decreases, it can cause corrosion to the cooling tower parts, hence pH is maintained at 7.0.

To maintain pH Sulphuric acid is used to adjust the pH of cooling tower water. Hydrochloric acid is not used in place of sulphuric acid as the H+ icon of hydrochloric acid can form bonds with ca+ and mg+ present in form of hardness in water.

In place of base, sodium hydroxide is used to reduce the pH of cooling tower water and hence maintain the pH of the cooling water system.

Scalent Inhibitors

Scaling and deposition is a major problem in cooling towers. Several minerals are present in the cooling tower water as soluble and insoluble forms. Evaporation takes place in the cooling towers and because of this, the scale-forming minerals presents started to concentrate and because of that scaling occurs. Scales such as calcium carbonate, silica, and calcium phosphate, calcium sulfate are found in the water of the cooling tower.

To prevent scaling, pre-treatment is performed to remove the hardness of water by passing through ion exchange columns where ca++ and mg++ ions are removed.

Algaecides & Biocides

In a cooling tower, several types of impurities are present in the water such as organic, inorganic, and other salts. Over the period of time, micro-organism growth occurred along with algae formation. Hence to prevent those microbial growths, biocides are dosed which contains bromine and chlorine. These chemicals kill bacterial growth, prevent algae formation and improve cooling tower water quality.

Corrosion Inhibitors

Cooling tower water contains minerals and which cause corrosion. This corrosion not only weakens the structure but also do metal loss. To prevent and minimize the rate of corrosion, corrosion inhibitors such as Cathodic or anodic inhibitors. These inhibitors create a thin layer or coating on the surface of the metal which prevents the access of metal surface.


Foaming in a cooling tower is another problem that can be caused by many reasons such as excessive or overdosing of chemicals, Excessive Alkalinity in water, High Degree of Suspended Solids, or process contamination. Hence to prevent foaming, defoamer chemicals are used in the cooling towers. These defoamers chemical breaks the air bubble and release air from them and hence defoam the water.

These are the cooling tower water treatment chemicals that are used in maintaining water quality and parameters of cooling water.

FAQ (Cooling tower water treatment chemicals)

What is the pH of cooling tower water?

pH of water in a cooling tower is maintained as neutral i.e. of 7 pH. As acidic or basic water can damage the pipes and equipment such as heat exchangers and reactors jacket.

What chemicals are used in cooling towers?

Various types of chemicals are dosed in cooling towers to maintain cooling water quality. Chemical such as
pH Adjusters
Corrosion Inhibitors
Scale Inhibitors
Algaecides and Biocides

Why are biocides used in cooling water?

Microbial growth is one of the major problems in cooling water. To prevent and control microbial and bacteria in cooling water systems, biocides are used and improved water quality.

Why H2SO4 is used in cooling towers and not HCL is not to adjust pH?

Cooling water is raw water that contains calcium and magnesium as hardnesses. If we dose HCL, it will form an H+ ion which forms a bond with ca+ and mg+ ion, and form salts which can cause scaling.

Why acid is used in cooling towers?

Sulphuric acid (H2SO4) is used in cooling towers to maintain pH.

Wrapping Up

This is a detailed tutorial on what are the cooling tower chemical dosing and what are chemicals used in cooling tower water treatment and addition to it, why these are important for maintaining cooling tower water parameters. In meantime, you can follow us on LinkedIn – Chemical Tweak to keep yourself updated with the latest post. If you have any doubt realated to this post, feel free to use comment section and if you have some topic that you want us to cover then share your suggestion in the comment section.

Avatar Of Ronak Prajapati

Me - Founder of Chemical Tweak - A Chemical Engineer by profession and a part-time self-trained technology blogger.

7 thoughts on “Chemicals used in cooling tower water treatment”

  1. If PH high (above 8ph) which chemical need to be added?

    If PH low (below 7) which chemical need to be added ?

    • Controlling pH is essential in any cooling tower.
      If the pH is above 8, we need to add sulphuric acid and if the pH is below 7, we need to add NaOH.

  2. Founded in 2007 Green Genesis Engineering Ltd. is a professional engineering company doing green business and offering water purification and related services with a team of professional and skilled workers & management offering a large portfolio of water treatment/management services designed to help plant personnel and end-user organizations to get the most out of their water treatment system.


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