Fifteen minutes to six months
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The shortest rows
pH, chlorine total residual and dissolved oxygen by probe: "Analyze within 15 minutes." These are field measurements with a meter, not samples to carry home.
Which is worth saying to somebody buying bottles
If the parameter is pH, you do not need a sample container, you need a meter at the water. A bottle of water measured at the laboratory is a different pH from the one at the bank.
The preservation clock
"Except where noted in this Table II and the method for the parameter, preserve each grab sample within 15 minutes of collection."
Which puts preservation in the field
Not at the vehicle, not at the laboratory. Fifteen minutes from the moment the sample is taken, which means the cooler and the reagents go to the water with you.
The short holding times
Coliform and E. coli at 8 hours, toxicity at 36 hours, nitrate and BOD and elemental phosphorus at 48 hours. These decide the day, not just the bottle.
A bacterial sample at 8 hours is a logistics problem
Collection, transport and the start of the analysis inside one working day. Sampling a remote site on a Friday afternoon is a wasted trip.
The long rows
Hardness and boron at 6 months, with acid preservation. Chloride and bromide and fluoride at 28 days with none required.
Which shows what preservation buys
The same water, held for 6 months instead of 48 hours, because an acid stopped the thing that was going to change. Preservation is time.
Cool is a number, not an instruction
Most rows say cool to 6 degrees C or below. Several bacterial rows say below 10. A cooler with ice is the method and a warm car is a failed sample.
Plan the route around the shortest holding time in the set
A single trip collecting eight parameters is governed by the 8 hour one. That is a trip planned backwards from the laboratory's opening hours.