If water samples are filtered before analysis, how should the results be noted?

• A. Dissolved
• B. Total
• C. Particulate
• D. Filtered

Answer: (A)

Filtration separates solids from the liquid, so the portion that passes through the filter consists of dissolved substances. When you filter a water sample before analysis, the measurement reflects the dissolved constituents, not the suspended or particulate matter. That’s why the correct note is "dissolved."

If you were to report "total," it would imply measuring both dissolved and particulate forms, which isn’t the case after filtration. Reporting "particulate" would refer to what the filter retains, not what passes through. "Filtered" is an operational description rather than a fraction of the sample to report. In standard water analysis, filtered samples are described as measuring the dissolved fraction, typically defined as what passes through the chosen filter size (e.g., 0.45 μm).