What goes wrong

It was the wrong bottle

On this page11

PET read as P Which is the single commonest version of this Boron sampled in glass Oil and grease sampled in plastic Which is the shape of every failure here The sample was preserved at the truck The holding time ran out on a Friday A dissolved oxygen sample had a bubble A compliance sample went into an uncertified container The fix is a card in the kit References

The failure produces a number, not an error. That is what makes it expensive.

PET read as P

Polyethylene terephthalate is not polyethylene. The letters are close enough to pass a tired check and the polymer is different, and PET does not appear in Table II under any code.

Which is the single commonest version of this

146 of the 359 containers on this shelf are PET, and it is clear and cheap and obviously a sample bottle to look at. That is exactly why it gets used.

Boron sampled in glass

The row is "P, FP, or Quartz" with no G, because borosilicate glass is named for its boron. A glass bottle hands the analyte to the sample.

Oil and grease sampled in plastic

The row is G alone. A polymer wall adsorbs it and the result reads low, with nothing visible to suggest anything happened.

Which is the shape of every failure here

No leak, no breakage, no obviously spoiled sample. A plausible number that is wrong, which is worse than a sample that visibly failed.

The sample was preserved at the truck

The rule is within 15 minutes of collection, which for a site a walk from the road means carrying the preservation to the water.

The holding time ran out on a Friday

An 8 hour bacterial holding time collected at 3pm is a sample that cannot reach an open laboratory. The trip has to be planned from the laboratory's hours backwards.

A dissolved oxygen sample had a bubble

The specification names the bottle and the top because the measurement is about excluded air. One bubble and the number is not the water's.

A compliance sample went into an uncertified container

Clean-looking is not certified, and the certificate is the evidence that the container contributed nothing. Nothing on this shelf carries one.

The fix is a card in the kit

Analyte, letter, material, preservation, holding time. Five columns for the parameters you actually sample, laminated, in the bag. It answers every failure on this page at the water.

References

40 CFR 136.3, Table II, "Required Containers, Preservation Techniques, and Holding Times", footnote 1: "'P' is for polyethylene; 'FP' is fluoropolymer (polytetrafluoroethylene [PTFE]; Teflon(R)), or other fluoropolymer, unless stated otherwise in this Table II; 'G' is glass; 'PA' is any plastic that is made of a sterilizable material (polypropylene or other autoclavable plastic); 'LDPE' is low density polyethylene." Footnote 2: "Except where noted in this Table II and the method for the parameter, preserve each grab sample within 15 minutes of collection." ecfr.gov

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.