When using surface waters for drinking water supplies, what is a general rule regarding their treatment?

Surface waters, such as rivers, lakes, and reservoirs, are subject to contamination from various sources, including agricultural runoff, industrial discharges, and urban pollution. Because they are exposed to the environment and can come into contact with numerous pollutants, a general rule is to assume that these waters are contaminated until proven otherwise. This perspective informs the treatment processes that must be implemented to ensure the water is safe for human consumption.

By considering surface waters as contaminated, water treatment facilities are required to engage in thorough testing and rigorous treatment procedures, such as filtration, disinfection, and sometimes chemical treatment, to remove or neutralize potential contaminants and pathogens. This foundational principle emphasizes the necessity of treating surface waters with caution, prioritizing public health and safety.

Fluorides, softening processes, and aeration may be part of specific treatment protocols but are not universally required for all surface waters. Each of these methods has specific applications depending on the particular characteristics and intended uses of the water being treated. However, the primary consideration remains that surface waters should be regarded as potentially contaminated to guide appropriate treatment measures effectively.