Define where the measurement belongs
Temperature and other rapidly changing properties can require field measurements to describe source conditions. A delivered sample may describe a different time and condition.
Keep the field record
Use the project’s instrument, calibration and documentation requirements. Record location, date, time and units alongside the sample identifiers.
Distinguish field and laboratory findings
Do not combine a field observation and a later laboratory value as if both described the same measurement moment. Keep the method and context visible.
Coordinate the scope
State which measurements the field team will perform and which are requested from the laboratory. Resolve gaps before collection rather than assuming a bottle can reconstruct every source property.
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.