Learn Hardcore Chinese: nǐ duō hē shuǐ ba.

多/少 + Verb + Object Examples:
多吃蔬菜。 “Eat more vegetables.”
少看手机。 “Look at your phone less.” Putting 多 before the verb 喝 makes it “drink more (water).”

What is the function of the sentence-final particle 吧 (ba)? Can I omit it?

吧 softens the tone and turns it into a gentle suggestion rather than a blunt command.

With 吧: friendly suggestion/advice.
Without 吧: more direct/imperative (sounds like an order in many contexts). Note: 吧 also has another use to show a guess/assumption (e.g., 你是学生吧), but here it’s the “let’s/please” suggestion use. Don’t confuse 吧 (ba, neutral tone) with 吗 (ma), the yes–no question particle.

Can I say 喝多水 or 喝水多 instead?

No for advice. Use these instead:

Correct for “do more”: 多喝水.
To describe quantity you drink (statement): 我喝很多水。 “I drink a lot of water.”
Descriptive pattern: 水喝得多。 “(Someone) drinks a lot of water.”
Warning: 喝多了 means “drank too much (alcohol)/got drunk,” not “drank a lot of water.”

What’s the difference between 多喝水, 多喝点水, and 多喝一些水?

多喝水: general “drink more water” (neutral strength).
多喝点水: “drink a bit more water” (softer, more colloquial).
多喝一些水: “drink some more water” (a bit more formal/literal than 点). All are fine; 多喝点水 is extremely common in speech.

Why is there no measure word before 水? Can I add one?

水 (water) is a mass noun, so no measure word is needed for the general action. If you want to be specific:

喝一杯水 “drink a glass of water”
喝一口水 “take a sip of water”
喝点(儿)水 “drink a little water”
多喝几口水 “take a few more sips of water”

Is 你 necessary? Can I use 您, or drop the subject?

You can say 您多喝水吧 to be polite to an older person or stranger.
In casual speech (especially text or when context is clear), you can drop it: 多喝水吧.
Keeping 你 can sound more direct; choose based on relationship and tone.

Is this polite? In what contexts is it appropriate?

It’s a friendly suggestion, commonly said when someone is sick, tired, or in hot weather. With 吧, it’s not rude. To be extra gentle/polite, try:

您多喝点水吧。
记得多喝水。
最好多喝水。
要不，还是多喝点水吧？ (very soft)

How do I say “Don’t drink too much water”?

别喝太多水。 (colloquial prohibition)
不要喝太多水。 (a bit more formal or careful warning)
Softer suggestion: 少喝点水吧。 “Drink a little less water.”

Could I say 喝更多(的)水?

Grammatically yes, but it’s more written/formal or contrastive. In everyday speech, 多喝水 is the idiomatic choice.

喝更多的水 often appears in instructions or formal advice.
多喝水 sounds most natural in conversation.

Any tone or pronunciation tips for this sentence?

你 nǐ (3rd), 多 duō (1st), 喝 hē (1st), 水 shuǐ (3rd), 吧 ba (neutral).
No 3–3 sandhi occurs here because 你(3) is followed by 多(1), not another third tone.
吧 is neutral; keep it light.
喝 is first tone hē; don’t pronounce it as hè.

What’s the difference between 吧 (ba) and 把 (bǎ)? They sound similar.

吧 (ba, neutral tone): sentence-final particle for suggestions/softening (as here) or assumptions.
把 (bǎ, third tone): a preposition for the “ba-construction” (e.g., 把门关上 “close the door”).
Different tones, characters, and functions.

How can I make the advice stronger or softer?

Stronger:
- 一定要多喝水。 “You must drink more water.”
- 你要多喝水。 “You should drink more water.”
Softer:
- 多喝点水吧。
- 要不，还是多喝点水吧？
- Add a softening particle: 多喝水哦/呀/哈。

Are there regional or colloquial variants?

North: 多喝点儿水吧 (with 儿化).
Taiwan/colloquial: 多喝水啦。
Texting: 多喝水哦/呀 to sound friendly.

Is there any cultural nuance to this advice?

Yes. In Chinese-speaking cultures, telling someone to drink more water—often even 多喝热水 “drink more hot/warm water”—is a very common, caring piece of everyday health advice. It’s usually taken as concern, not sarcasm.

How do I turn this into a question like “Should I drink more water?”

我应该多喝水吗？ (using 应该 “should”)
我要不要多喝水？ (A-not-A pattern; very natural)
我是不是应该多喝水？ (seeking confirmation)

How do I tell someone else to make a third person drink more water?

让他多喝水吧。 “Let him drink more water.”
叫她多喝点水。 “Tell her to drink a bit more water.”

What’s the difference between “drink some water first” and “drink more water”?

“Drink some water first”: 先喝点水吧。 (focus: first/for now)
“Drink more water”: 多喝水吧。 (focus: amount/ongoing habit)