Photo: Wikimedia Commons · CC BY-SA 4.0
Thesis
The key words in “其水用山水上江水中井水下” are not ornament. They mark where Tang tea names, vessels and provenance meet.
Text
“For water: mountain spring is best, river water next, and well water lowest.”
Context
古人择水：山泉水最优，江水次之，井水最下。核心是"活"与"清"。
Evidence
- Collation: 各本一致。此句为全书最广为引用的择水标准，后世茶书多沿其说。
- Existing readings: 吴觉农指出：陆羽"山水上"之论影响千年，其内核是"活水为上"——山泉活水含氧高、杂质少；现代水质科学证实，矿物质适度、溶氧充足的活水确实更宜茶。
Analysis
The annotation matters less as philology than as a distinction between name and thing. 各本一致。此句为全书最广为引用的择水标准，后世茶书多沿其说。 Once names settle, picking, grading and trade can share a language.
Conclusion
The section does not give a universal rule. It demonstrates a method: read the text, the annotation and the Tang context together before making a modern claim.
Source: The Classic of Tea, Chapter V · The Brewing, section 1; the original is in the public domain.
Ask what period this person lived in.