What is commonly used to monitor the quality of water in sanitation practices?

A pH meter is a crucial instrument in monitoring water quality, particularly in sanitation practices. The pH level of water can greatly influence its safety and usability, as it affects the solubility and biological availability of chemical constituents, including nutrients and contaminants. Regularly measuring the pH of water helps to assess whether it falls within safe ranges for human consumption, recreational use, and ecological health.

While other instruments like conductivity meters can also provide important information about water quality by measuring the electrical conductivity of the water (which relates to ion concentration), they do not specifically determine acidity or alkalinity. A barometer, on the other hand, measures atmospheric pressure and does not assess water quality at all. Therefore, the pH meter is specifically critical for understanding the chemical properties of the water, making it the most relevant tool among the options provided.