Yes, that's confusing. The article mentions 2 trial sites located in 2 relatively small California cities. Both are extremely close to CPST itself. Also the fact that CPST is mentioned specifically, I assumed it was, infact, CPST used.
It is too bad the article wasn't clearer, but the fact that CPST was mentioned in that particular, unusual, and innovative method of purifying the water leads me to think that it was used at those two sites.
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