What parameter is used to indicate clarity of water?

The clarity of water is primarily indicated by turbidity. Turbidity measures the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye. These particles can include sediments, microorganisms, and organic matter that disperse light, resulting in reduced transparency. High turbidity levels can signify contamination and can negatively affect water quality, as it impacts the ability for light to penetrate the water and can inhibit the processes of photosynthesis in aquatic ecosystems.

In contrast, pH measures the acidity or alkalinity of water, which is crucial for understanding chemical interactions but does not directly relate to clarity. Chlorine residual indicates the presence of chlorine in water, primarily used as a disinfectant, but it does not provide information about the visual clarity of the water. Alkalinity reflects the water's capacity to neutralize acids and is more related to the buffering capacity rather than visual characteristics. Therefore, turbidity is the most relevant parameter for assessing water clarity.