Kirk here with another article about water use by TSMC. It favors the view that there's no concern about the water usage:

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The current groundwater usage in Kumamoto Prefecture, home to 1.67 million people and businesses, is around 300–400 million tons per year. The saying “water is overflowing” is not an exaggeration. The water usage of JASM (pronounced “Jasumu” in Japanese), a joint venture between TSMC and Japanese companies, is 3.1 million tons annually, less than 0.1% of Kumamoto’s total groundwater. Okano Hideyuki, executive director of the Kyushu Economic Association, said, “Kumamoto’s groundwater has little to filter out, so the cost of purifying ultra-pure water (Ultra Pure Water) for semiconductors is much lower.”
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I think, though, that there are some reasonable counter arguments -- reasons to be concerned if not apoplectic. I'll try to follow up later if I can.