What goes wrong

It leaked in the cooler

On this page11

Grit on the thread The full bottle froze Cool is a number The label came off So label the container, not the lid And write the collection time on it Two samples from the same site were indistinguishable The cooler was packed with the bottles loose The chain of custody stayed in the truck Pack the kit the night before References

Everything in a cooler is wet. Including the thing that identifies the sample.

Grit on the thread

Soil or sediment between the cap and the neck. The cap seats badly, the bottle leaks on the drive, and the cooler contaminates every other sample in it.

The full bottle froze

A sample filled to exclude headspace has nowhere to expand. Ice directly against a container, or a cooler left overnight in a truck, breaks it.

Cool is a number

Most rows say 6 degrees C or below, several bacterial rows say below 10. Cold is not the same as cool enough, and neither is a cooler that started cold eight hours ago.

The label came off

Paper in melting ice. An unlabelled sample in a cooler of identical bottles is a set of samples, not a result, and no laboratory can rescue it.

So label the container, not the lid

Lids get swapped during filling and in transport. The identity belongs on the thing holding the sample.

And write the collection time on it

Every holding time in the table counts from collection. A sample without one has no holding time and therefore no defensible result.

Two samples from the same site were indistinguishable

Same bottle, same day, different depth or different replicate, and nothing on the label to say which. A naming scheme decided before the trip is what prevents it.

The cooler was packed with the bottles loose

Glass against glass over a rough track. Dividers or a bag per sample cost nothing and save the field day.

The chain of custody stayed in the truck

Which is not a packaging failure and is the one that voids a compliance sample completely. The form travels with the cooler.

Pack the kit the night before

Containers labelled, preservation ready, cooler pre-chilled, spares counted. Every failure on this page is a decision made at six in the morning that could have been made the evening before.

References

40 CFR 136.3, Table II, selected rows. Oil and grease: G, cool to 6 degrees C or below and acidify to pH below 2, 28 days. Phenols: G, 28 days. Phosphorus (elemental): G, 48 hours. Fluoride: P, no preservation required, 28 days. Silica: P or Quartz, 28 days. Boron: P, FP, or Quartz, nitric acid to pH below 2, 6 months. Cryptosporidium and Giardia: LDPE with field filtration, 1 to 10 degrees C, 96 hours. Dissolved oxygen by probe: G, bottle and top, analyze within 15 minutes. Chlorine, total residual: P, G, analyze within 15 minutes. pH: P, FP, G, analyze within 15 minutes. Coliform and E. coli: PA, G, 8 hours. Hardness: P, FP, G, 6 months. Nitrate: P, FP, G, 48 hours. ecfr.gov

The Davis Pack Supply catalog, measured 19 October 2026. The field sampling shelf is 768 rows: 359 containers and 409 closures. 5 mL to 950 mL with a median of 118; 124 containers at 60 mL or under, 211 at 120 or under, 317 at 500 or under, and nothing above a litre. 146 PET, 108 glass, 92 HDPE, 13 PP, no LDPE and no fluoropolymer. 194 jars, 163 bottles, 2 tubes. 103 clear, 82 white, 52 amber, 34 natural. Closures: 346 continuous thread, 27 dome lids, 14 phenolic, 11 liners and sealing discs, 6 specialty.

Written from 40 CFR 136.3 Table II and from the catalog as it stood on 19 October 2026. Part 136 governs Clean Water Act compliance monitoring; it is used here for everything else as the best available statement of what a container does to a water sample, not as a rule that binds a student with a creek. Nothing on this shelf is sold precleaned or certified for regulated sampling, and no preservation chemistry is given, because that belongs to the laboratory running the analysis.