What is the primary cause of rust formation in water tanks?

The primary cause of rust formation in water tanks is corrosion due to oxygen exposure. When water is stored in a tank, it can come into contact with oxygen from the air. This exposure leads to a chemical reaction between the metal in the tank and oxygen, which, in the presence of water, results in the formation of iron oxide, commonly known as rust. This process is accelerated in environments where moisture is present, as water acts as an electrolyte, facilitating the corrosion process.

While excessive humidity can contribute to rusting, it primarily does so by increasing the water content in the air, thus fostering an environment where corrosion can occur. However, the direct contributor to the rusting mechanism itself is the oxygen that reacts with the tank's metal in the presence of moisture.

High mineral content in the water can also affect water quality, but it is not the main driver of rust formation. Similarly, using improper materials for the tank construction could lead to issues in terms of durability or integrity, but the fundamental process of rust is primarily attributed to oxygen exposure and the subsequent chemical reactions.