Quality concerns with surface water sources Which of the following correctly describes typical issues associated with untreated surface water?

Introduction / Context:
Surface waters—rivers, lakes, and reservoirs—are exposed to runoff, discharges, and biological activity. Recognizing inherent risks guides the selection of treatment processes to ensure safe potable water.

Given Data / Assumptions:

• No prior treatment of the raw surface water.
• Catchment activities (agriculture, urban runoff, industry) may affect quality.
• Microbial presence is possible due to animal and human sources.

Concept / Approach:
Typical impairments include suspended solids (turbidity), natural organic matter, nutrients, and pathogens (bacteria, viruses, protozoa). Treatment usually requires coagulation–flocculation, sedimentation, filtration, and disinfection, sometimes preceded by pre-oxidation and followed by advanced steps as needed.

Step-by-Step Solution:

Verification / Alternative check:
Regulatory standards for potable water focus on turbidity, coliforms, and chemical limits precisely because these risks exist in surface sources.

Why Other Options Are Wrong:
Choosing only one aspect ignores the breadth of common surface-water problems.

Common Pitfalls:
Underestimating microbial hazards due to clear-looking water; turbidity is not the only indicator of safety.

Final Answer:
All of the above