What is the purpose of a coupon in water treatment?

The purpose of a coupon in water treatment primarily relates to its role in assessing corrosiveness. Coupons are small samples of metal, typically made of materials that are commonly found in pipes and fixtures used in water systems. They are exposed to the water being treated to evaluate the potential for corrosion that could affect the system's integrity and functionality.

When a coupon is placed in a water system, it undergoes the same environmental conditions, including the chemical composition of the water, temperature, and flow dynamics. By periodically inspecting these coupons, operators can determine how much corrosion has occurred over time and make necessary adjustments to mitigate corrosion, such as adjusting pH, alkalinity, or adding corrosion inhibitors to the water.

Coupons are specifically designed for this purpose and are essential tools in ensuring the long-term health and safety of water distribution systems. Other methods for measuring water clarity, pH levels, or microbial activity do not address the need for understanding the corrosive potential of the water in relation to the materials in the system. These other measurements are important for overall water quality, but they serve different specific functions compared to the use of coupons.