I don't want to dismiss this article outright, but it seems to freely conflate mining with transactions, consumption with usage, and large-scale operations with any other setup equivalence.
That aside, the figures aren't particularly useful without some baseline comparisons to typical water usage in other server farms to know if that's a lot, a little, or just average. How much water is "consumed" by YouTube, Facebook, X/Twitter, Google, Citibank, JP Morgan Chase, Bank of America, ICBC, the global banking system collectively, the Pentagon, etc.?
Finally, why the focus on Bitcoin? The article states it's a particular concern without stating the difference in water usage against other cryptocurrencies that makes it so. After the next halving event (predicted to occur in April 2014) will there even be a single system anywhere in the world still dedicated to Bitcoin mining ? Won't a large portion of the Bitcoin water usage issue simply evaporate when that happens?
While it does mention changes to Ethereum, it fails to state what the actual water usage reduction was; something which would be particularly insightful since Ethereum can no longer be mined thus the water usage would be strictly transactional. The article suggests other cryptocurrencies should adopt similar methods but fails to point out that ending mining entirely in order to adopt a system where the largest stakeholders gain shares faster isn't a practical consideration for less mature cryptocurrencies even if one overlooks the obvious fairness issue that introduces.