What factor must be considered when determining the frequency of sampling for larger water systems?

When determining the frequency of sampling for larger water systems, regulatory requirements are the most critical factor to consider. Regulatory agencies, such as the Environmental Protection Agency (EPA) in the United States, set specific guidelines and standards that dictate how often water quality testing must be performed. These regulations are designed to ensure public safety by monitoring contaminants and ensuring that water quality meets health standards.

In larger water systems, these requirements can vary based on factors such as the type of water sources, potential contamination risks, and the population served. However, the overarching framework provided by regulatory requirements is what dictates the minimum frequency of sampling that must be adhered to, ensuring consistent monitoring and compliance with public health standards. Compliance with these regulations is crucial for maintaining the safety and quality of the water supply.