If a coupon inserted into a water main lost weight over time, what does this indicate about the water?

When a coupon inserted into a water main loses weight over time, it typically indicates the presence of corrosive conditions within the water. Corrosion occurs when the water interacts with the materials of the coupon (often metal) and leads to a breakdown or loss of mass. The loss of weight signifies that the water has the ability to leach away material, which is a hallmark of corrosive water.

Corrosive water can result from several factors, including low pH levels, high levels of dissolved oxygen, or an imbalanced concentration of other minerals. When these conditions are present, they can accelerate the corrosion process, leading to weight loss in any metal component exposed to the water over time.

Understanding this property is crucial for water operators, as it helps monitor water quality and protect infrastructure from damage caused by corrosion.