Why “to drink water” in Shanghainese is 吃茶?

Question

While listening to two people speaking Shanghainese （沪语）I realized that they have two different ways to say “water”.

Based on the pronunciation I heard:

• the first is /sɨ/ similar to 死 in Mandarin, heard in the word 矿泉水
• the second is /zu/ similar to 足 in Mandarin (with voiced sibilant), heard in /ha zu/

The first is clearly Shanghainese for 水 (“water”).

I looked up the other one and it appears it’s 茶 （”tea”). As a matter of fact, 喝水 in Shanghainese is 吃茶 /ha zu/.

It’s literally “eat tea”.

How come that “drink water” becomes in Shanghainese so distant from its meaning, so much that it doesn’t even use the usual character for “water”?

Answer 1

Here is the entry for 吃茶 in《上海方言词典》on p. 350:

Here is the entry for 茶 in《上海方言词典》on p. 205:

茶 is defined in both of these as "boiled water." It's not a hard jump to make as most drinking water is boiled before consumption. Similarly, "白开水" can be used in Mandarin to refer to "water," under the pure assumption that it has been boiled an cooled to make it suitable for drinking. Tea 茶 is likely also short for 茶水, perhaps both meaning "the water used to make tea" along with "tea water."

吃 is a common verb in rural cultures to refer to any sort of oral consumption. Many dialects have words like 吃酒 or 吃烟 to speak of drinking and smoking. Likewise, 吃茶 is not uncommon in rustic areas.

吃茶 for plain water is a bit harder to get, but all things considered the extensions of its components is easy to see.

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Adding on to this, here is an entry from a second dictionary 上海话大辞典 p. 71

My favorite is 咖啡茶, that gives me a good chuckle. Looks like 茶 has genericized for sure.