“A Test Method for Evaluating Water Conditioning Adjuvants” was published as a standardized test method in order to evaluate new products. Artificial hard water is mixed to 1,000 mg L−1 CaCl and MgCl. Water-conditioning agents are mixed with herbicides and evaluated for the ability to overcome the antagonistic effects of cations in the water. Although this is an effective test method, a comparison of the salt type used has never been conducted. The objective of this research was to validate the standardized test method in comparison to three artificially mixed hard-water samples mixed to 500 mg L−1 calcium using CaCl, CaFo, and CaNO3. Field trials were conducted near Hillsboro, ND, in 2016 and 2017. Glyphosate and mesotrione were applied at 342 and 70 g ae ha−1, respectively. Three types of water conditioners were evaluated with glyphosate diammonium sulfate (AMS), AMS replacement, and monocarbamide dihydrogen sulfate (AMADS). AMADS was not included in the mesotrione study. Indicator species included flax (Linum usitatissimum L.), amaranth (Amaranthus cruentus L.), sunflower (Helianthus annuus L.), and conventional corn (Zea mays L.) for the glyphosate study and amaranth, foxtail millet (Setaria italica (L.) P. Beauvois), quinoa (Chenopodium quinoa Willd.), and sunflower for the mesotrione study. Herbicide antagonism was similar between the simulated hard-water samples. Within each type of water-conditioning adjuvant, antagonism was overcome similarly in all water types. The results of these studies validate the previously published test method.