While this approach clearly gives the best indication of glaze stability, it is not without complicating factors. The largest complication is deciding what standards to use when assessing test results. In lieu of that, the most conservative approach is to use the primary and secondary standards for drinking water where they exist for materials of interest to potters. MCL is the maximum contaminant level permissible. Note that the lead and cadmium standards, which must be followed if you use these materials, are from 7 to 200 times less strict than the above maximum contamination levels for drinking water, depending on the type of pottery vessel and whether it is subject to federal or California standards.
Similar standards are in place in other countries.
Another problem with using drinking water standards as a reference is that there are no standards for several materials potters use, including cobalt, lithium and strontium. This probably can be done without limiting the color palette or glaze aesthetics in any meaningful way. The simplest is a three-day vinegar soak. If the glaze changes noticeably in either color or sheen, it is not durable enough for functional ware. A good way to do this test is by submerging half of a grease-free glaze sample in a cup of vinegar.