What does conductivity (EC) in water indicate?

Conductivity, often measured as electrical conductivity (EC), is a key parameter in assessing the quality of water. It indicates the concentration of dissolved ions, including salts and minerals, in the water. When water contains these dissolved substances, it can conduct electricity, and the level of conductivity directly correlates with the concentration of ions present.

This means that when conductivity is high, it typically reflects higher levels of dissolved salts such as sodium, calcium, chloride, and bicarbonates, which are crucial in evaluating water quality for various purposes, including agriculture, drinking water, and ecological health.

The other options either relate to different aspects of water chemistry or do not directly measure the variables that conductivity assesses. For example, pH level is a measure of acidity or alkalinity, and while related to water chemistry, it does not provide a direct analysis of ionic content. Similarly, the presence of copper would not indicate conductivity as a broader measure of overall dissolved substances, and water hardness, which pertains specifically to calcium and magnesium levels, is also not a comprehensive measure that reflects the total ionic concentration like conductivity does. Thus, the correct answer highlights the focus on dissolved salts and minerals.