A circumstance in which it is more economical or practical to provide treatment at the source versus in a water treatment facility is referred to as:

• A. Source control
• B. In situ treatment
• C. Point-of-use treatment
• D. On-site filtration

Answer: (B)

Providing treatment at the source refers to addressing contamination or treatment needs directly at the location where the water is sourced, instead of transporting the water to a centralized treatment facility. This approach is often more economical and practical due to reduced costs associated with transportation and the ability to handle contaminants immediately at the source.

In situ treatment specifically focuses on the treatment done directly in the original place where contaminants exist, which can include methods to remediate or manage water quality issues without the need to handle the water in a separate facility. This can lead to quicker responses to contamination problems, making it a highly efficient solution in certain contexts.

While source control also relates to managing contaminants at their origin, it is more about prevention strategies rather than treatment. Point-of-use treatment and on-site filtration focus on treating water for individual uses after it has already been sourced, rather than addressing issues directly at the source. Therefore, the description aligns most closely with in situ treatment as it encompasses the idea of applying remedial methods directly where the water is sourced.