Define the investigation hypothesis
Describe the observed issue, water source, suspected targets and the decision the results need to inform. Separate an exploratory screen from a regulatory submission.
Choose meaningful comparisons
Background, source and downstream or treated samples can serve different roles. Give every location a stable ID and document its relationship to the investigation.
Resolve matrix and preparation
Groundwater, surface water, wastewater and companion solids may require different analytical pathways. Do not extend a water-method description to solids without reviewing its applicability.
Use results to refine the next step
A concentration difference can suggest follow-up questions but does not establish the source of contamination on its own. Interpret it with hydrologic, process and sampling context.
Related testing & guidance
Technical & service references
Vanguard water-testing menuEPA: Clean Water Act method questionsEPA: Drinking-water analytical methodsSource review: November 8, 2026. The agreed method and project scope govern the testing.