The decoctions of unprocessed aconite root (uzu) were prepared with the tap water samples collected in Tianjin and Shanghai in China, and the contents of alkaloids in the decoctions were compared to those prepared with purified water or with tap water collected in Niigata, Japan. The contents of aconitine-type diester alkaloids (ADA) in the decoctions prepared with tap water collected in China were significantly lower than those with purified water or tap water in Niigata. It was speculated that this difference appeared by buffering effect of bicarbonic anion in tap water in China to decline pH of the decoction. When uzu was decocted with glycyrrhiza, ginger, or jujube, the contents of ADA in the decoctions exhibited the tendency to have higher levels than those prepared using unprocessed aconite root singly, and also this tendency was observed more remarkably when the decoctions were prepared with tap water collected in China. It was suggested that even the decocting period was fixed, unexpected change of the contents of ADAs might be induced by the differences in the properties of water used for decoction or the crude drugs decocted with aconite root. The physicians in the era when “Songban Shanghanlun” had established may have adjusted the contents of ADA in the decoction by carefully choosing the crude drugs combined to aconite root.

Although the descriptions of shigyakukachotanto in “Waitaimiyaofang” and tsumyakushigyakukachotanjuto in “Songban Shanghanlun” are quite similar to each other, the specifications of the dosages of crude drugs and the water volume in the books were considerably different. Focused on the specified water volume to decoct these formulas, each reasonable decocting period was estimated, then the decoctions were prepared using hard water that was common in mainland China. The dosages of aconite root were 2­-fold different between these two formulas, but the contents of aconitine-­type diester alkaloids (ADA) in both decoctions were found in the range of 1.2—1.4­-fold. It was suggested that in order to control the efficacy and the safety of aconite, the decocting period was well regulated by the specification of water volume for decocting at this ancient era. Moreover, the dosages of aconite root and glycyrrhiza in bukuryoshigyakuto (BSGT) formula of “Songban Shanghanlun” are equal to those of shigyakuto (SGT) but the specified water volume to begin decocting is as about twice as that of SGT. When prepared using hard water, BSGT resulted to make the contents of ADA lower and those of non-­ester alkaloids higher compared with those of SGT decoction. It was suggested the spe­cific water volume for each formula prescribed in classical Chinese medicine had considerable significance to determine the dosages of chemical ingredients in the decoctions especially in the circumstances using hard water to prepare them.