Learn Hardcore Chinese: xiàbān qián wǒ chángcháng hē yìdiǎnr shuǐ. - Before getting off work, I often drink a little water.

下班前我… slightly emphasizes the time (“As for before work ends, I often …”).
我下班前… starts with the person, then adds the time.
我常常在下班前… sounds very natural and explicit, with 在 marking the time phrase.

In everyday speech, all three are fine; context usually matters more than the small shift in emphasis.

Does 下班前 literally mean “before I finish work”? Where is the subject “I”?

下班前 literally means “before getting off work / before work finishes.”

下班 = finish work / get off work
前 = before, in front of (in time or space)

Chinese doesn’t always need to specify the subject inside time expressions. The subject of the whole sentence (我) is understood to apply to the action within that time frame.

So 下班前我常常喝一点儿水 is naturally interpreted as:

Before *I get off work, I often drink a little water.*

You don’t need to (and normally wouldn’t) say something like 在我下班之前我常常… unless you really want to stress “before I (specifically) get off work” in contrast to someone else.

Can I say 在下班前 or 在下班之前 instead of just 下班前? Any difference?

Yes, you can say:

在下班前，我常常喝一点儿水。
在下班之前，我常常喝一点儿水。

Differences:

下班前 – very common, short, natural in conversation.
在下班前 – adds 在, explicitly marking it as a time phrase. Slightly more formal/explicit but still common.
在下班之前 – a bit more formal or emphatic because of 之前 instead of just 前.

Meaning-wise, they are basically the same. The original 下班前我常常… is already fully natural.

What exactly does 常常 mean here? Is it the same as 经常?

常常 (chángcháng) means “often / frequently”.

我常常喝一点儿水。 = I often drink a little water.

常常 and 经常 (jīngcháng) overlap a lot and are often interchangeable:

我常常去那里。
我经常去那里。

Both mean “I often go there.”

Nuance (very small):

Some speakers feel 经常 is a bit more common in northern speech and in writing.
常常 can feel slightly more colloquial or rhythmic in some sentences.

In your sentence, you can freely swap:

下班前我经常喝一点儿水。

Still natural and correct.

Where can I put 常常 in the sentence? Are all of these okay?

下班前我常常喝一点儿水。
下班前我喝常常一点儿水。
下班前我喝一点儿水常常。

Only 1 is correct.

Basic pattern for adverbs like 常常:

(Time) + Subject + 常常 + Verb + Object

So:

✅ 下班前我常常喝一点儿水。
❌ 下班前我喝常常一点儿水。 (adverb is in the wrong place)
❌ 下班前我喝一点儿水常常。 (adverb cannot go at the end like this)

You can also move the time expression:

✅ 我下班前常常喝一点儿水。
✅ 我常常在下班前喝一点儿水。

What’s the difference between 一点儿水, 一些水, and just 水? Why say 一点儿水 here?

All are possible, but they feel different:

水 – just “water” in general.
- 我喝水。 = I drink water.
一点儿水 – “a little water / a bit of water.”
- Suggests a small amount, quite natural in speech.
一些水 – “some water.”
- Also fine, but for uncountable nouns like water, 一点儿水 is more common in casual speech.

In this sentence, 喝一点儿水:

Emphasizes that it’s just a small amount, maybe like a quick sip or small drink before leaving work.
Feels very natural and idiomatic.

What’s the difference between 一点 and 一点儿? Why add 儿?

一点 (yìdiǎn) and 一点儿 (yìdiǎnr) mean the same thing: “a little / a bit.”

儿 (r) is an “er-hua” suffix used heavily in northern Mandarin (e.g. Beijing dialect).
In many textbooks and in northern speech, you’ll see 一点儿.
In the south and in Taiwan, people usually say 一点 (no 儿).

So:

喝一点儿水。 (more northern)
喝一点水。 (more southern/Taiwan)

Both are correct. The only real difference is regional accent/style, not grammar.

Why don’t we use a measure word like 杯 in 喝一点儿水? Could we say 喝一杯水 instead?

You can say 喝一杯水, but it’s a different idea.

喝一点儿水 – drink a little water, amount is vague and probably small.
喝一杯水 – drink one cup of water, a specific container and amount.

In Chinese, when the exact quantity/container doesn’t matter and the focus is just “some water,” 一点儿水 is perfectly natural. If you specifically mean “a glass/cup of water,” then use:

下班前我常常喝一杯水。

Should there be a 了 after 喝, like 喝了一点儿水? How does that change the meaning?

Both forms are possible but not identical.

喝一点儿水 – neutral, describes the action in general; here it’s a habitual action:
- Before I get off work, I often drink a little water. (a routine)
喝了一点儿水 – 了 marks the action as completed:
- I (have) drank a little water. (a specific time in the past or completed event)

In your sentence with 常常 (often), we are talking about a habit, not a single completed event, so:

下班前我常常喝一点儿水。 (correct for habits)
下班前我常常喝了一点儿水。 sounds odd, because 常常 (often) clashes with 了 (single completed event).

Use 了 when describing a specific occurrence, e.g.:

刚下班前，我喝了一点儿水。
Right before getting off work, I drank a little water.

Can I drop 我 and just say 下班前常常喝一点儿水?

Grammatically, yes, you can omit 我 if the subject is very clear from context.

下班前常常喝一点儿水。
Could be understood as:
- Before getting off work, (I/you/people) often drink a little water.

However:

Without 我, the subject becomes more general or ambiguous.
If you’re talking about your own routine and there’s no prior context, 下班前我常常喝一点儿水 is clearer and more natural for learners to use.

Native speakers often omit pronouns when they’re obvious from context, but as a learner it’s safer to keep 我 until you’re very comfortable with the language flow.

How do I know this sentence is present tense (a habit) and not past or future? There’s no tense marking.

Chinese doesn’t use verb tenses like English. Instead, it uses:

time words: 昨天 (yesterday), 明天 (tomorrow), 现在 (now), 下班前 (before getting off work)
aspect markers: 了, 过, 着
frequency words: 常常, 经常, 总是

In 下班前我常常喝一点儿水:

常常 indicates a habitual action.
下班前 describes a regular time frame.

Together, they strongly suggest a present habit:

I often drink a little water before I get off work (as a routine).

To make it clearly past habit, you might say:

以前下班前我常常喝一点儿水。
In the past, before getting off work, I often drank a little water.

Are there other natural ways to say this same idea in Chinese? Which sounds most natural?

All of these are natural and common:

下班前我常常喝一点儿水。
我下班前常常喝一点儿水。
我常常在下班前喝一点儿水。
在下班前，我常常喝一点儿水。

Nuance:

3 (我常常在下班前…) is extremely common and very clear:
我 + 常常 + 在下班前 + 喝一点儿水
1 and 2 are also very natural; they just shift where the time phrase sits.
4 is slightly more formal or written-sounding because of the comma and leading 在下班前.

In everyday conversation, 1 and 3 are especially typical.