Which of the following is not a factor that can alter groundwater sample quality?

• A. Solvent used to weld PVC casing together
• B. Drilling fluid
• C. Improperly stored casing
• D. Temperature of groundwater

Answer: (D)

The key idea is that groundwater sample quality is determined by what contaminates the sample during collection, handling, and storage. Solvent residues from welding PVC casing can leach into the water and alter its chemistry. Drilling fluids bring salts, organics, and additives that can skew analyses. Improperly stored casing can release metals or other contaminants into the sample. The temperature of groundwater, by itself, isn’t a source of contamination; it’s a natural property that may be important for preservation or interpretation, but it does not introduce new substances into the sample. So the temperature of groundwater is not a factor that alters the sample’s quality in the sense of contamination.