Learn Hardcore Japanese: sigoto no aida ni mizu wo komame ni nomimasu.

間 (あいだ) by itself is a noun meaning “interval / span of time” or “while.”
When you add に to it after a time expression, it often means “during / in the course of.”

仕事の間に – during work
授業の間に – during class

Grammar point:

A 間: a state continuing throughout the whole time
A 間に: one or more events happen at some point(s) during that time

Here, 水をこまめに飲みます are repeated actions that happen many times throughout the work period, so 仕事の間に (events happening during that period) is natural.

What is the nuance of 仕事の間に compared with 仕事中に or 仕事のとき?

All can often be translated as “during work,” but the nuance shifts a bit.

仕事の間に
- Focus on the time span of working
- “While I’m working / during my work period”
- Quite natural for something that happens repeatedly throughout that time
仕事中に
- 中（ちゅう） emphasizes “while in the middle of doing something”
- Stronger sense of “while you are actively working”
- Slightly more “in the middle of the activity” feeling than 間に
仕事のとき
- Literally “when (it is) work / at times of work”
- Broader and a bit more vague; can mean “on work days / when I’m at work”

In this sentence, 仕事の間に nicely matches the idea of “over the course of my working time, I repeatedly drink water.”

Does 仕事の間に mean “between jobs” (like being unemployed between two jobs)?

No.

Here 間 means “the period while you are doing the work you currently have.”
“Between jobs” as in unemployed is more like:

仕事と仕事の合間に – between one piece of work and another
転職活動中 – while job-hunting
仕事がない間 – during the time I don’t have a job

仕事の間に in this sentence is simply “during work / while I’m working.”

What does こまめに mean exactly? How is it different from たくさん or よく?

こまめに means “frequently and in small, regular amounts”, often with a nuance of carefulness or diligence.

Comparisons:

こまめに飲む
- Drink little by little, at short intervals, regularly
- Emphasizes frequency and regularity, not total quantity
たくさん飲む
- Drink a lot (in quantity)
- Focus is on how much, not how often
よく飲む
- Drink often / a lot (habitually)
- General “often,” no special nuance of small, frequent sips

So this sentence suggests: “I take care to drink water regularly, bit by bit, during work.”

Why does こまめ have に after it? What part of speech is こまめ?

こまめ is originally a na-adjective (こまめな) meaning things like “diligent, attentive, thorough in small tasks.”

Na-adjectives usually form their adverb with に:

静か（な） → 静かに – quietly
丁寧（な） → 丁寧に – politely
こまめ（な） → こまめに – diligently / frequently (in small regular ways)

So こまめに here is an adverb, modifying the verb 飲みます and meaning “in a frequent, regular way.”

What is the role of を in 水をこまめに飲みます?

を marks the direct object of the verb.

水 – water (object)
を – object marker
飲みます – drink

So 水を飲みます = “(I) drink water.”

The adverb こまめに just slips in before the verb:

水をこまめに飲みます – I drink water frequently / regularly

In very casual speech, people sometimes drop を, but the standard and clear form keeps it.

Can I change the word order and say こまめに水を飲みます instead? Is that different?

Yes, こまめに水を飲みます is also completely natural and means the same thing.

Both are fine:

水をこまめに飲みます
こまめに水を飲みます

Japanese word order is relatively flexible, especially with adverbs. The main rule is that the verb comes at the end. Native speakers tend to choose the order that feels most natural in context or matches what they want to emphasize slightly, but here there is no strong difference.

Why is there no word for “I” in this sentence?

Japanese often omits the subject when it is obvious from context.

In English, we must say “I drink water…”, but in Japanese:

If you are talking about your own habits at work, everyone assumes the subject is “I”.
If you are describing rules for staff, people might take it as “(You should) drink water frequently during work.”

The subject (私, あなた, etc.) is only added when needed for clarity or emphasis. So the bare 仕事の間に水をこまめに飲みます is normal and natural.

What tense or aspect is 飲みます? Does it mean “drink,” “will drink,” or “am drinking”?

飲みます is the polite non-past form of 飲む.

Non-past in Japanese covers:

Habitual actions: “I drink (regularly).”
Future actions: “I will drink.”

Here, combined with こまめに and the time phrase 仕事の間に, it clearly expresses a habit / rule / regular practice:

“I (habitually) drink water frequently while I’m working.”
Or as a rule/instruction: “Drink water frequently during work.”

It is not specifically the progressive “am drinking right now.” For that, you’d use 飲んでいます.

What politeness level is this sentence? Is 飲みます formal?

飲みます is the polite (ます-form) of 飲む.

Levels:

飲む – plain / casual
飲みます – polite, used in most public, work, and neutral situations

So 仕事の間に水をこまめに飲みます。 is polite but not super-formal; good for talking to colleagues, writing simple instructions, etc.

Casually to a close friend, you might say:

仕事の間に水をこまめに飲む。

How is 間 read here, and does the reading change in other contexts?

In 仕事の間に, 間 is read あいだ → しごとのあいだに.

Common readings and uses of 間:

あいだ – interval/period (as in this sentence)
- 仕事の間 – during work
- 夏休みの間 – during summer vacation
ま – in some set expressions or when counting intervals
- このドアの間（このドアのま）– in between these doors (more literary/technical)

You mainly need あいだ for “during/while,” as in this sentence.