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B1 noun 11 min read

水道水

Practice it Examples Notes & Tips 水道水 in 30 Seconds

Explanation 水道水 in your Level:

At the A1 level, you just need to know that 'suidousui' means 'tap water'. Japan's tap water is very safe, so you can drink it. You might see this word in your house or at school. It is made of 'suidou' (water pipes) and 'sui' (water). If you are thirsty, you can say 'mizu' (water), but 'suidousui' is the name for the water that comes from the sink. In A1, we use simple sentences like 'This is tap water' or 'I drink tap water'. It is a useful word for daily life in Japan.

At the A2 level, you should be able to use 'suidousui' in basic sentences about daily habits. For example, 'I use tap water for cooking' or 'The tap water is cold'. You start to see the difference between 'suidousui' and 'mineral water'. In Japan, most people drink tap water because it is free and safe. You might hear this word when talking about your apartment or when you are in a park. It is important to remember that 'suidou' is the system, and 'suidousui' is the water itself.

At the B1 level, you can use 'suidousui' to discuss more complex topics like water quality or the environment. You might talk about why you use a water filter (jousuiki) for your tap water or compare the taste of tap water in different cities like Tokyo and Osaka. You can understand news reports about 'suidou-kyoku' (the water bureau) and how they manage the tap water supply. You should also be comfortable using it in the context of saving water (sessui) during the summer or in emergency preparation (bousai).

At the B2 level, you can use 'suidousui' in technical or semi-formal discussions. You might discuss the 'Water Supply Act' (Suidou-hou) or the chemical standards that make Japanese tap water drinkable. You can explain the difference between 'suidousui' and 'idomizu' (well water) or 'tennensui' (natural spring water) to someone else. You are also able to understand the nuances of when to use 'suidousui' versus more polite terms like 'o-hiya' in a restaurant or 'inryousui' in official documents.

At the C1 level, you have a deep understanding of the socio-economic and historical context of 'suidousui' in Japan. You can discuss the history of water infrastructure from the Edo period to modern times. You might engage in debates about the privatization of water services (suidou mineika) and how it might affect the quality and price of tap water. You can use the word fluently in academic or professional settings, such as environmental science or urban planning, and understand all related idioms and compound words.

At the C2 level, 'suidousui' is a word you use with native-level precision across all domains. You can interpret subtle cultural attitudes toward tap water—such as the regional pride in 'delicious tap water' in places like Kumamoto—and use this knowledge in high-level negotiations or literary analysis. You understand the most obscure technical terms related to water treatment and can discuss the global positioning of Japan's water technology. The word is part of a vast web of related concepts you navigate effortlessly.

Practice it Examples Notes & Tips

水道水 in 30 Seconds

Suidousui means tap water, specifically the water coming from public utilities.
It is safe to drink in Japan, meeting high safety standards.
It differs from 'mizu' (general water) and 'mineral water' (bottled).
Used in contexts of cooking, cleaning, utility bills, and health.

The Japanese word 水道水 (すいどうすい - suidousui) is a compound noun that literally translates to "water from the water path" or more commonly, "tap water." In Japan, this word carries a significant amount of cultural weight because Japan is one of the few countries in the world where tap water is consistently safe to drink directly from the faucet without additional filtration. This reliability makes the word suidousui a standard part of daily life, whether you are at home, in a restaurant, or at a public park.

Etymology: The word is composed of three Kanji characters: 水 (sui - water), 道 (dou - path/way), and 水 (sui - water). Together, 水道 (suidou) refers to the water supply system or plumbing, and adding the final 水 specifies the liquid itself.

日本の水道水は、そのまま飲んでも大丈夫です。(Japan's tap water is safe to drink as is.)

When you enter a Japanese home, you might see people filling a kettle with suidousui to make tea. In professional settings, such as restaurants, if you ask for water (mizu), you are almost always being served suidousui unless it is a high-end establishment that specifies mineral water. It is important to note that while mizu is a general term for water, suidousui specifically denotes the source. People use this term when discussing water quality, utility bills, or comparing tap water to bottled mineral water (ミネラルウォーター).

Daily Context: Used when talking to the water department, installing a water filter (浄水器 - jousuiki), or checking if the water in a specific area is potable.

この地域の水道水はとても美味しいですね。(The tap water in this region is very delicious, isn't it?)

In urban environments like Tokyo, some people might complain about the slight smell of chlorine in the suidousui, leading them to use filters or buy bottled water. However, in mountainous regions like Nagano or Hokkaido, the suidousui is often praised for being as good as, if not better than, premium bottled brands. Understanding this distinction helps learners navigate conversations about health, environment, and daily necessities.

Technical Nuance: Technically, suidousui refers to water treated by a public utility. In rural areas, some people might use 'idomizu' (well water), which is not suidousui.

水道水を飲む習慣がありますか？ (Do you have a habit of drinking tap water?)

Overall, while the word is simple, its usage reflects the high standard of living and public infrastructure in Japan. It is a neutral, everyday term that every learner should know to function in a Japanese-speaking environment, especially when dealing with household chores, health discussions, or dining out.

Using 水道水 (suidousui) in sentences requires understanding its role as a concrete noun. It typically functions as the object of a verb (drinking, using, filtering) or the subject of a descriptive sentence. Because it is a specific type of water, it is often contrasted with other types like tennensui (natural water) or jouge-suidou (water and sewage services).

Common Verb Pairings: Nomu (to drink), tsukau (to use), tameru (to collect/store), and jousui-suru (to purify).

料理にはいつも水道水を使っています。(I always use tap water for cooking.)

When constructing sentences, you might want to talk about the quality or the cost. For example, 'The tap water smells like chlorine' would be Suidousui ga enso-kusai. If you are talking about the bill, you would use suidou-dai (water bill), but when discussing the water that actually comes out of the faucet, suidousui is the correct term. In a formal context, you might see it used in warnings or instructions, such as 'Please do not drink the tap water' (Suidousui wa nomanaide kudasai), often found in older buildings or specific industrial sites where the water might not be potable.

Asking Questions: You can ask about the safety of water in a new city by saying: "Kono machi no suidousui wa nomemasu ka?" (Can I drink the tap water in this town?)

震災に備えて、水道水をボトルに蓄えておく。(Store tap water in bottles to prepare for an earthquake disaster.)

In a comparative sentence, you might say, Suidousui yori mineral water no hou ga suki desu (I like mineral water more than tap water). This structure helps you express preferences clearly. Additionally, in a scientific or educational context, you might hear about suidousui no kensa (tap water testing). This highlights the word's versatility across different registers, from casual home talk to official reports.

Using with Adjectives: Common adjectives include tsumetai (cold), oishii (delicious), and nigotta (cloudy/muddy).

暑い日は、冷たい水道水が一番です。(On hot days, cold tap water is the best.)

Finally, remember that suidousui is a very literal term. If you just want to ask for a glass of water to drink, mizu or o-mizu is more natural. Use suidousui when the specific source of the water (the tap) is relevant to the conversation.

You will encounter the word 水道水 (suidousui) in a variety of real-world settings in Japan. One of the most common places is in news broadcasts or newspapers, especially during the summer months when water shortages might occur or when there are reports on water quality infrastructure improvements. The term is essential for understanding public health announcements.

At the Supermarket: You might see signs for 'water stations' where you can fill bottles with purified water, often contrasting it with regular suidousui.

ニュース：今年の夏は雨が少なく、水道水の節約が呼びかけられています。(News: With little rain this summer, a call for saving tap water is being made.)

In a domestic setting, parents often talk to their children about not wasting suidousui. You'll hear phrases like Suidou wo tome-nasai (Turn off the tap), which implicitly refers to the suidousui flowing out. If you are renting an apartment, the real estate agent or the building manager might explain the water system using this word. For instance, they might mention that the suidousui comes from a storage tank on the roof (chusuigou) or directly from the city line.

In Schools: Children are taught about the water cycle and how suidousui is treated at the local 'jousuijo' (water purification plant).

学校の蛇口から出る水道水を飲む。(Drinking tap water coming from the school's faucet.)

Another interesting place you'll hear this word is in discussions about disaster preparedness (bousai). Japan is prone to earthquakes, and one of the first things people are told to do is secure suidousui in bathtubs or containers before the pipes potentially break. You will see this word in manuals, on government websites, and in neighborhood association meetings.

In Restaurants: While a waiter says 'o-mizu', in the kitchen, staff might refer to 'suidousui' when washing vegetables or boiling noodles.

このレストランでは、水道水を浄水して提供しています。(This restaurant purifies tap water before serving it.)

Whether you are listening to a podcast about sustainable living, reading a lease agreement, or just talking to a neighbor about why the water is turned off for maintenance, suidousui is the specific, accurate term you'll encounter.

One of the most frequent mistakes learners make with 水道水 (suidousui) is using it when the general term mizu (water) is more appropriate. While suidousui is technically correct if the water comes from a tap, it sounds overly clinical or technical in casual social situations. For example, if you are thirsty and ask a friend, "Suidousui wo kudasai?" (Can I have some tap water?), it sounds like you are specifically requesting the tap variety as opposed to bottled water, which might be a bit awkward unless that's exactly what you mean.

Mistake 1: Over-specificity: Using 'suidousui' at a dinner table instead of 'o-mizu'. 'O-mizu' is polite and covers all drinking water.

❌ レストランで：水道水を一杯ください。(Give me a glass of tap water.)
✅ レストランで：お水を一杯ください。(Give me a glass of water.)

Another common error is confusing suidousui with suidou. Suidou refers to the waterworks system, the pipes, or the utility service itself. If you say "Suidousui ga kowareta" (The tap water is broken), it makes no sense. You should say "Suidou ga kowareta" (The plumbing/water system is broken) or "Jaguchi ga kowareta" (The faucet is broken). Suidousui is the liquid substance, not the delivery mechanism.

Mistake 2: Confusing with 'Nama-mizu': Some learners use 'nama-mizu' (raw water) to mean tap water. While technically tap water is 'unboiled', 'nama-mizu' often refers to untreated natural water from a stream, which can be dangerous.

❌ この川の水道水を飲む。(Drinking the tap water of this river - incorrect because rivers don't have tap water.)

Learners also sometimes forget that suidousui is a single word. They might try to say "suidou no mizu" (water of the tap). While this is grammatically correct and understandable, it is less natural than the compound noun suidousui. Furthermore, in travel contexts, don't assume suidousui is always drinkable just because the word exists. Always look for signs that say "Nomemasen" (Not drinkable) in older parks or temples.

Mistake 3: Pronunciation: Failing to elongate the 'ou' in 'suidou'. If you say 'suidosui', it might not be understood clearly.

By avoiding these pitfalls—overusing the term in social settings, confusing the liquid with the system, and mispronouncing the long vowels—you will sound much more like a native speaker.

To truly master the vocabulary surrounding water, it's helpful to compare 水道水 (suidousui) with its synonyms and related terms. Each word has a specific nuance and use case that distinguishes it from the basic tap water.

水 (Mizu / O-mizu): The most general term. Use this for drinking water, water in a glass, or water in nature. It doesn't specify the source.
飲料水 (Inryousui): Formal/Technical term for 'potable water' or 'drinking water'. You'll see this on labels or in emergency kits.
浄水 (Jousui): Purified water. This refers to suidousui that has passed through a filter. Many modern Japanese faucets have a 'jousui' setting.

この蛇口は水道水と浄水の切り替えができます。(This faucet can switch between tap water and purified water.)

When you are at a convenience store, you won't find anything labeled suidousui. Instead, you'll see Mineral Water (ミネラルウォーター) or Tennensui (天然水 - natural water). The latter is often used by brands like Suntory to emphasize that the water comes from a natural spring or mountain source, implying it is superior to regular tap water.

井戸水 (Idomizu): Well water. Still common in rural Japan. People might prefer this for its taste, but it must be checked for safety.
沸騰水 (Futtousui): Boiled water. Often used when talking about making baby formula or ensuring safety in areas with poor water quality.

都会の水道水より、田舎の井戸水の方が冷たくて美味しい。(Well water in the countryside is colder and tastier than tap water in the city.)

In a restaurant, you might also hear the word O-hiya. This is a specific term used by staff and customers to refer to 'cold drinking water'. It is almost always tap water with ice, but the name focuses on the temperature and the service rather than the source (suidousui).

Summary Table: - Suidousui: Tap water (Source focused)
- O-mizu: Water (General/Polite)
- O-hiya: Cold water (Restaurant setting)
- Jousui: Purified water (Quality focused)

By knowing these alternatives, you can choose the word that best fits the social context, whether you're being technical, polite, or descriptive.

How Formal Is It?

Fun Fact

In the Edo period, Japan already had an advanced 'suidou' system using wooden pipes to bring fresh water to the city, which was rare for that time.

Pronunciation Guide

UK suː.iː.doʊ.suː.iː

US su.i.do.su.i

The pitch usually starts low on 'su', rises on 'i-do', and stays relatively flat until the end.

Rhymes With

Kaisui (Seawater) Inryousui (Drinking water) Kouzui (Flood) Yousui (Irrigation water) Kensui (Pull-up exercise) Gensui (Field marshal) Shinsui (Soaking) Dansui (Water cutoff)

Common Errors

Pronouncing 'suidou' as 'suido' (forgetting the long 'o').
Mixing up the 'sui' and 'shui' sounds.
Putting too much stress on the final 'sui'.
Pronouncing 'u' like the English 'you' instead of a compressed Japanese 'u'.
Incorrectly pausing between 'suidou' and 'sui'.

Difficulty Rating

Reading 3/5

Kanji are common but require knowing the 'Sui' and 'Dou' readings.

Writing 4/5

Writing 'Dou' (道) can be tricky for beginners.

Speaking 2/5

Easy to pronounce if you remember the long vowel.

Listening 2/5

Distinctive sound, easy to pick out in conversation.

What to Learn Next

Prerequisites

水 (Water) 道 (Road/Path) 飲みます (To drink) 安全 (Safe) 蛇口 (Faucet)

Learn Next

浄水器 (Water purifier) ミネラルウォーター (Mineral water) 断水 (Water cutoff) 水道代 (Water bill) 下水道 (Sewage)

Advanced

高度浄水処理 (Advanced water treatment) トリハロメタン (Trihalomethane) 水質基準 (Water quality standards) 簡易水道 (Small-scale water supply) 貯水池 (Reservoir)

Grammar to Know

Compound Nouns

水道 (Waterworks) + 水 (Water) = 水道水 (Tap water).

Particles 'de' for Means

水道水で顔を洗う (Wash face with tap water).

Particles 'wo' for Object

水道水を飲む (Drink tap water).

Potential Form

水道水が飲めます (Can drink tap water).

Adjective Modifiers

冷たい水道水 (Cold tap water).

Examples by Level

これは水道水です。

This is tap water.

Basic 'A wa B desu' structure.

水道水を飲みます。

I drink tap water.

Direct object 'wo' with the verb 'nomu'.

水道水はおいしいです。

Tap water is delicious.

Adjective 'oishii' describing the noun.

水道水は安いです。

Tap water is cheap.

Adjective 'yasui' meaning inexpensive.

水道水で手を洗います。

I wash my hands with tap water.

Particle 'de' indicating the means or tool.

公園に水道水があります。

There is tap water in the park.

Existence verb 'arimasu' for inanimate objects.

水道水は冷たいです。

The tap water is cold.

Adjective 'tsumetai' for temperature of objects.

水道水をください。

Tap water, please.

Polite request using 'kudasai'.

料理に水道水を使います。

I use tap water for cooking.

Particle 'ni' indicating purpose.

日本の水道水は安全です。

Japanese tap water is safe.

Na-adjective 'anzen' describing the noun.

水道水よりお茶が好きです。

I like tea more than tap water.

Comparative structure 'A yori B no hou ga suki'.

毎日、水道水を飲みますか？

Do you drink tap water every day?

Adverb 'mainichi' (every day).

水道水が止まりました。

The tap water has stopped.

Intransitive verb 'tomaru' (to stop).

水道水をボトルに入れました。

I put tap water into a bottle.

Particle 'ni' for the destination of the action.

この水道水は飲めません。

This tap water is not drinkable.

Potential form 'nomemasen' (cannot drink).

水道水で野菜を洗ってください。

Please wash the vegetables with tap water.

Request form 'te-kudasai'.

水道水の塩素の臭いが気になります。

I am bothered by the smell of chlorine in the tap water.

Verb 'ki ni naru' (to be bothered by/concerned about).

浄水器を通すと、水道水がもっとおいしくなります。

If you use a water purifier, the tap water becomes tastier.

Conditional 'to' indicating a natural consequence.

災害のために、水道水を備蓄しておく必要があります。

It is necessary to stockpile tap water for disasters.

Noun 'bichiku' (stockpile) + 'oku' (to do in advance).

東京の水道水は昔よりきれいになりました。

Tokyo's tap water has become cleaner than before.

Comparative 'mukashi yori' (than before).

水道水の品質は自治体によって異なります。

The quality of tap water varies depending on the municipality.

Grammar 'ni yotte' (depending on).

レストランで水道水を頼むのは恥ずかしくないです。

It's not embarrassing to ask for tap water at a restaurant.

Nominalizing a verb with 'no wa'.

水道水の節約を心がけましょう。

Let's try to save tap water.

Volitional form 'mashou' with 'kokoro-gakeru'.

この地域は水道水が非常に冷たくて美味しいです。

The tap water in this area is extremely cold and delicious.

Adverb 'hijou ni' (extremely).

水道水の安全基準は法律で厳しく定められています。

Safety standards for tap water are strictly defined by law.

Passive voice 'sadamerarete-imasu'.

高度浄水処理によって、水道水の味が格段に向上しました。

The taste of tap water has improved significantly due to advanced purification treatment.

Noun 'koujou' (improvement) with 'shita'.

水道水に含まれるミネラル成分を調査する。

To investigate the mineral components contained in tap water.

Relative clause 'fukumareru' (contained in).

最近では、水道水をそのまま飲む人が減っているようです。

Recently, it seems the number of people who drink tap water as is is decreasing.

Conjecture 'you desu' (it seems).

水道水の供給が止まると、生活に大きな支障が出ます。

When the tap water supply stops, it causes major disruption to daily life.

Conditional 'to' indicating a result.

水道水とミネラルウォーターのブラインドテストを行った。

We conducted a blind test of tap water and mineral water.

Noun 'blind test' with 'okonatta' (conducted).

マンションの貯水槽が汚れていると、水道水の質が落ちます。

If the apartment's water tank is dirty, the quality of the tap water drops.

Conditional 'to' with 'shitsu ga ochiru'.

水道水は貴重な資源であることを忘れてはいけません。

We must not forget that tap water is a precious resource.

Prohibition 'te wa ikemasen'.

日本の水道水インフラは、世界でもトップクラスの普及率を誇っています。

Japan's tap water infrastructure boasts one of the highest coverage rates in the world.

Verb 'hokoru' (to boast/be proud of).

水道水の民営化議論は、公共性と採算性の間で揺れています。

The debate over tap water privatization wavers between public interest and profitability.

Grammar 'A to B no aida de yureru'.

老朽化した水道管の更新が、水道水の安全性を維持する上での課題です。

Replacing aging water pipes is a challenge in maintaining the safety of tap water.

Grammar 'ue de no' (in the process of).

地下水の枯渇は、将来的な水道水の確保に深刻な影響を及ぼしかねません。

The depletion of groundwater could potentially have a serious impact on securing tap water in the future.

Grammar 'kanemasen' (might happen/could potentially).

水道水のトリハロメタン濃度を基準値以下に抑制する技術。

Technology to suppress trihalomethane concentration in tap water below standard values.

Technical terminology usage.

震災時の水道水供給体制の脆弱性が浮き彫りになった。

The vulnerability of the tap water supply system during the earthquake was highlighted.

Idiomatic expression 'ukibori ni naru'.

水道水への不信感から、ウォーターサーバーを導入する家庭が増加している。

Due to a lack of trust in tap water, households installing water dispensers are increasing.

Particle 'kara' indicating a reason/cause.

各自治体は、水道水のブランド化を図り、その美味しさをアピールしている。

Each municipality is trying to brand their tap water and promote its deliciousness.

Verb 'hakaru' (to aim for/plan).

水道水は単なる生活用水に留まらず、都市の公衆衛生の根幹を成すものである。

Tap water is not merely domestic water; it forms the very foundation of urban public health.

Grammar 'ni todomarazu' (not limited to).

水資源の偏在は、水道水供給の持続可能性を脅かす地政学的なリスクとなり得る。

The uneven distribution of water resources can become a geopolitical risk threatening the sustainability of tap water supply.

Auxiliary verb 'uru/eru' (can/is possible).

水道水における微量化学物質の長期的影響については、依然として議論の余地がある。

There is still room for debate regarding the long-term effects of trace chemicals in tap water.

Idiom 'giron no yochi ga aru'.

高度経済成長期に整備された水道網の更新費用は、莫大な財政負担となっている。

The cost of updating the water network established during the rapid economic growth period is a huge financial burden.

Relative clause modifying 'koushin hiyou'.

水道水の供給プロセスにおけるエネルギー効率の最適化が急務である。

Optimizing energy efficiency in the tap water supply process is an urgent task.

Noun 'kyuumu' (urgent matter).

気候変動に伴う水源の変容は、水道水の浄化プロセスに再考を迫っている。

Changes in water sources due to climate change are forcing a reconsideration of the tap water purification process.

Grammar 'ni saikou wo semaru'.

水道水という公共財の公平な分配は、社会正義の観点からも極めて重要である。

The equitable distribution of the public good that is tap water is extremely important from the perspective of social justice.

Noun 'koukyouzai' (public good).

微細プラスチックの水道水への混入実態の解明が待たれる。

Elucidation of the actual state of microplastic contamination in tap water is awaited.

Passive voice 'matareru' (is awaited).

Common Collocations

水道水を飲む

水道水を使う

水道水の質

水道水の臭い

水道水の料金

水道水を貯める

水道水を浄水する

水道水の供給

水道水の検査

水道水の節約

Common Phrases

水道水で十分

— Tap water is enough/sufficient (no need for bottled).

飲み物は水道水で十分です。

水道水が飲める国

— A country where tap water is drinkable.

日本は水道水が飲める数少ない国の一つだ。

水道水のカルキ抜き

— Removing chlorine from tap water (often for fish tanks).

金魚のために水道水のカルキ抜きをする。

水道水が冷たい

— The tap water is cold (common in winter).

冬は水道水が冷たくて顔を洗うのが辛い。

水道水の出しっぱなし

— Leaving the tap water running.

水道水の出しっぱなしはもったいない。

水道水が濁る

— The tap water becomes cloudy or muddy.

工事の後は水道水が濁ることがある。

水道水の安全神話

— The 'myth' or deep belief in the safety of tap water.

日本の水道水の安全神話が揺らいでいる。

水道水の硬度

— The hardness (mineral content) of tap water.

ヨーロッパの水道水は硬度が高い。

水道水の塩素

— The chlorine in tap water.

水道水の塩素が肌に合わない。

水道水のボトル詰め

— Bottling tap water (often for sale by cities).

市が水道水のボトル詰めを販売している。

Often Confused With

水道水 vs 水道 (Suidou)

Suidou is the infrastructure/pipes. Suidousui is the liquid water.

水道水 vs 生水 (Nama-mizu)

Nama-mizu is untreated water from nature. Suidousui is treated tap water.

水道水 vs 浄水 (Jousui)

Jousui is tap water that has been specifically filtered/purified.

Idioms & Expressions

"湯水のように使う"

— To use something (usually money) as if it were hot water/tap water; to spend lavishly.

彼はお金を湯水のように使う。

Common

"水に流す"

— To let bygones be bygones; to forgive and forget (literally: to let it flow away in the water).

昔の喧嘩は水に流そう。

Common

"寝耳に水"

— A total surprise; like water in the ear while sleeping.

そのニュースは寝耳に水だった。

Common

"水と油"

— Like oil and water; two things that don't mix.

あの二人は水と油のような関係だ。

Common

"水を差す"

— To throw cold water on something; to discourage or interrupt.

楽しい雰囲気に水を差さないでください。

Common

"水際で作戦"

— A last-minute defense or a defense at the water's edge (often used for border control).

感染症を水際で食い止める。

Formal

"呼び水"

— Priming the pump; something that triggers a larger reaction.

彼の発言が議論の呼び水となった。

Abstract

"立て板に水"

— Speaking fluently and eloquently (like water flowing down a standing board).

彼女は立て板に水のごとく喋った。

Literary

"我田引水"

— Drawing water to one's own field; being selfish or twisting things to suit oneself.

それは我田引水な考え方だ。

Formal

"焼け石に水"

— A drop in the bucket; something that is completely inadequate (literally: water on a hot stone).

この程度の援助では焼け石に水だ。

Common

Easily Confused

水道水 vs 水道

Both contain 'suidou'.

Suidou is the service/pipes; Suidousui is the water itself.

水道が故障した (Pipes broke) vs 水道水を飲む (Drink tap water).

水道水 vs お水

Both refer to water.

O-mizu is general; Suidousui specifies it's from the tap.

お水をください (Socially natural) vs 水道水をください (Clinical).

水道水 vs 飲料水

Both mean drinking water.

Inryousui is a formal/technical category; Suidousui is a specific source.

飲料水の備蓄 (Stockpiling drinking water) vs 水道水が出る (Tap water comes out).

水道水 vs 天然水

Both are types of water.

Tennensui is natural spring water; Suidousui is municipal treated water.

天然水を買う (Buy natural water) vs 水道水を使う (Use tap water).

水道水 vs 生活用水

Both are used in daily life.

Seikatsu-yousui includes water for toilets/washing; Suidousui is the source liquid.

生活用水の不足 (Shortage of domestic water).

Sentence Patterns

[Noun] wa suidousui desu.

Kore wa suidousui desu.

Suidousui wo [Verb].

Suidousui wo nomimasu.

Suidousui no [Noun] ga [Adjective] desu.

Suidousui no aji ga hen desu.

Suidousui yori [Noun] no hou ga [Adjective] desu.

Suidousui yori mineral water no hou ga oishii desu.

Suidousui wo [Verb] tame ni [Action].

Suidousui wo bichiku suru tame ni bin wo kaimashita.

Suidousui ni [Noun] ga fukumareru.

Suidousui ni enso ga fukumareru.

Suidousui no [Noun] ni okeru [Noun].

Suidousui no kensa ni okeru mondaiten.

Suidousui wa [Noun] ni todomarazu [Noun] da.

Suidousui wa seikatsu-yousui ni todomarazu koukyouzai da.

Word Family

Nouns

水道 (Waterworks)

水 (Water)

上水道 (Clean water supply)

下水道 (Sewage system)

水道局 (Water bureau)

Verbs

断水する (To cut off water)

浄水する (To purify water)

給水する (To supply water)

排水する (To drain water)

Adjectives

水臭い (Watery/Distant/Formal)

水っぽい (Watery)

蛇口 (Faucet)

配管 (Plumbing)

塩素 (Chlorine)

カルキ (Bleach/Chlorine)

浄水器 (Water purifier)

How to Use It

frequency

Very common in daily life, news, and utility contexts.

Common Mistakes

Using 'suidousui' at a restaurant. → お水をください (O-mizu wo kudasai).
'Suidousui' sounds too technical for a social request. Use 'o-mizu' for drinking water.
Saying 'suidousui ga kowareta'. → 水道が故障した (Suidou ga koshou shita).
The water itself can't be 'broken'. You mean the plumbing or the system (suidou).
Confusing 'suidousui' with 'nama-mizu'. → 水道水 (Suidousui).
'Nama-mizu' often refers to potentially dangerous untreated natural water. Tap water is always 'suidousui'.
Mispronouncing 'suidou' as 'suido'. → 水道 (Suidou - long 'o').
Long vowels are crucial in Japanese. Shortening it makes the word harder to recognize.
Using 'suidousui' for the bill. → 水道代 (Suidou-dai).
The bill is for the service (suidou), not just the water liquid (suidousui).

Tips

When to be Specific

Use 'suidousui' when comparing it to mineral water or when talking about water quality. Otherwise, 'o-mizu' is usually enough.

Drink with Confidence

Don't be afraid to drink tap water in Japan. It's safe and free. Most public parks have fountains labeled with this word.

Noun Compounds

Japanese loves compounding nouns. Suidou + Sui is a classic example. Learn them as one unit rather than separate words.

Look for Filters

In Japanese kitchens, look for the word '浄水' (jousui) on the faucet. That is the filtered version of suidousui.

Ask the Hotel

If you are unsure at a hotel, ask 'Suidousui wa nomemasu ka?'. They will usually say 'Hai, daijoubu desu'.

Eco-Tip

Using suidousui in a reusable bottle is much more eco-friendly than buying plastic mineral water bottles daily.

Long Vowels Matter

Ensure you say 'suidou' with a long 'o'. If you say it too fast, it might sound like a different word.

Chlorine Awareness

If you have sensitive skin, be aware that suidousui contains chlorine. Some people use shower filters to mitigate this.

Soft Water Benefits

Because suidousui in Japan is soft, it's perfect for cooking rice and making dashi (soup stock).

Save Money

Drinking suidousui instead of buying tea or water at vending machines can save you 150 yen per bottle!

Memorize It

Mnemonic

Think of 'Sui' (Water) + 'Dou' (Road) + 'Sui' (Water). It's water that takes the road to your house!

Visual Association

Imagine a blue road (dou) made of water (sui) leading directly to your kitchen tap.

Word Web

Water Tap Safe Japan Utility Cooking Drinking Chlorine

Challenge

Go to your kitchen, point at the tap, and say 'Suidousui' five times. Then, fill a glass and say 'Suidousui wo nomimasu'.

Word Origin

The word is a Sinitic compound (Kango) consisting of 'suidou' and 'sui'. 'Suidou' originally meant any channel for water.

Original meaning: Water that travels through a constructed path or channel.

Japanese (Sino-Japanese origin).

Cultural Context

None. It is a neutral, safe topic. However, be aware that in some very old buildings, the water might not be potable.

In many English-speaking countries, tap water is also safe, but the flavor profile and mineral content (hard vs soft water) vary significantly compared to Japan's generally soft water.

Tokyo Waterworks Museum Suntory Tennensui commercials (contrasting with tap) Bousai (Disaster prevention) manuals

Practice in Real Life

Real-World Contexts

At Home

水道水を沸騰させる
水道水を料理に使う
水道水を飲む
水道水を節約する

At a Restaurant

水道水でいいです
水道水は無料ですか？
お水（水道水）をください
水道水は冷たいですか？

Emergency/Disaster

水道水を備蓄する
水道水が止まる
給水車から水道水をもらう
水道水の確保

Health/Environment

水道水の塩素を除く
水道水の安全性を確認する
水道水の質を調べる
水道水と健康

Travel

水道水は飲めますか？
水道水をボトルに詰める
ここの水道水はおいしい
水道水は飲まないほうがいい

Conversation Starters

"日本の水道水はそのまま飲んでも大丈夫だと思いますか？"

"あなたの国では、水道水を飲む習慣がありますか？"

"水道水とミネラルウォーター、どちらの方が好きですか？"

"水道水のカルキの臭いが気になったことはありますか？"

"水道水を美味しくするために、何か工夫をしていますか？"

Journal Prompts

今日飲んだ水道水の味について詳しく書いてみましょう。

もし水道水が使えなくなったら、あなたの生活はどう変わりますか？

水道水の節約のために、あなたが毎日できることを考えてみてください。

日本の水道水が世界的に見て安全だと言われる理由を調べて感想を書きましょう。

水道水とミネラルウォーターのどちらが環境に優しいか、自分の意見を書いてください。

Frequently Asked Questions

10 questions

Yes, Japan is one of the few countries where tap water is strictly regulated and safe to drink nationwide. The word 'suidousui' implies safety in a Japanese context.

You can, but it's more natural to say 'o-mizu'. Using 'suidousui' might sound like you are being overly specific about not wanting bottled water.

'Suidou' refers to the water supply system or the pipes. 'Suidousui' refers specifically to the water that comes out of those pipes.

Mainly to remove the smell or taste of chlorine, which is used for disinfection. They use a 'jousuiki' (purifier) for this purpose.

In most parts of Japan, 'suidousui' is soft water (nansui), which is good for making tea and Japanese cuisine.

You can ask: 'Kono suidousui wa nomemasu ka?' (Is this tap water drinkable?)

It means the 'water bill' or 'water fee'. It doesn't use the 'sui' at the end of 'suidousui'.

Very rarely, in some isolated mountain huts or very old, abandoned buildings. Usually, there will be a sign saying 'Nomemasen'.

'Jousui' is tap water that has been filtered. Many kitchen taps have a lever to switch between the two.

No, 'suidousui' specifically refers to the municipal public water supply.