Why is a sanitary survey of a water system necessary?

A sanitary survey of a water system is essential primarily because it assesses the safety and adequacy of the water supply. This comprehensive evaluation involves examining the water source, treatment processes, distribution systems, and any potential contamination risks. By identifying any possible sources of pollution and evaluating the overall infrastructure, a sanitary survey ensures that the water meets health standards and is safe for public consumption.

In contrast to the other choices, a sanitary survey is broader in focus than simply measuring specific contaminants like iron, determining pump size, or assessing water hardness. While those aspects can be part of a more detailed examination, the primary goal remains the overall safety and reliability of the water supply, making option A the most comprehensive and relevant choice.