Which classification pertains to a water system that does not use a treatment process?

The classification that pertains to a water system that does not use a treatment process is designated as DSS, which stands for "Distribution System Only." This classification specifically refers to systems where water is delivered to consumers without any treatment processes being applied, such as filtration or disinfection. It typically applies to systems that may source their water from non-contaminated, naturally occurring sources or wells that meet state and federal water quality standards without any further processing.

In contrast, the classifications WT1, WT2, and WT3 are associated with water treatment plants that implement varying levels of treatment processes. These classifications reflect the complexity and capacity of the treatment operations, where WT1 represents the simplest level of treatment with the least amount of operational complexity, and WT3 indicates a more advanced and complex treatment regimen. Therefore, when categorizing a system that operates solely in distribution and does not engage in any water treatment processes, DSS is the appropriate classification.