If an operation requires potable water/ice do they have to test EACH of their water uses individually?
No. Operations must show that ALL of their water uses are potable. The only way to do this is to take a water sample test, but this doesn’t mean they have to individually test all of their uses. How the operation chooses to demonstrate this potability is up to them. Depending on their set-up, one sample could show potability for a number of uses. For example, if an operation uses water from the SAME well for handwashing, cleaning of equipment and final rinse they may choose to test each of those individually OR they may choose to test only the final rinse water.
By testing only the final rinse water they can determine if the final rinse equipment is clean AND if the well supplying the handwashing water and water for cleaning of equipment is potable. In this case, the requirement for potable water could be met by testing only the final rinse equipment. Individual tests are another option and would accomplish the same thing.
If an operation takes individual tests it will be easy to determine sources of contamination, whereas it won’t be as easy if the final rinse test is being used to show potability of all the sources, and contamination is found in the final rinse water test. The operation will have to do some investigatory work to determine where the contamination is (e.g., the well itself, the final rinse equipment).