Kindly, consider the image below:
Can I say for the glass in the middle: "too few water" instead of "not enough water"? Are they equivalent in meaning?
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As others said, "too little" is more appropriate because you use "little" for uncountable nouns. An extra point, though: In my opinion, "too little" is a bit stronger than "not enough". For example, "not enough" could be slightly less than enough (say 70-90% as a ballpark), but "too little" (or "too few" where appropriate) may mean even less than that (the second glass in your image.)