Is cold water fine for laundry? What changes if I use hot water?
This answer is a draft. It stays unpublished until legal review and source verification are complete.
If you come from Europe or North America, washing at 40–60°C is probably normal for you. Japanese household machines, though, almost all wash in cold tap water, and most have no heater. Newcomers worry that a Japanese wash does not get clothes clean; Japanese readers worry that hot water ruins clothes. Here is how it works, along with what the numbers on a care label mean.
What each water temperature does
| Water temperature | Cleaning | Suits | Watch for |
|---|---|---|---|
| Around 10°C (winter tap water) | Detergent may not dissolve; skin oil solidifies and is hard to remove | — | Use liquid detergent, or dissolve powder in warm water first |
| 20–25°C (summer tap water) | Enough for everyday soiling | Everyday clothes in general | — |
| 30–40°C (leftover bath water, warm water) | Skin oil and sweat come out more easily. Oxygen bleach also works better | Yellowed shirts, towels, underwear, socks | Wool, silk and colours: check the upper limit on the label |
| 50–60°C | Effective against mites (50°C for 20–30 minutes) and many bacteria | Bedding and towels (cotton, label 60 or above) | Shrinkage, colour loss, creasing in synthetics. Check the machine's heat limit (many are rated to 50°C) |
- Reading the label: the number in the tub symbol is the maximum temperature (JIS L0001). "40" means you can wash in water or warm water up to 40°C. One bar underneath means a gentler cycle, two bars gentler still. Anything at or below the number is fine.
- Using leftover bath water (残り湯, nokoriyu — many Japanese machines have a pump hose for this): bath water for the wash cycle only; tap water for the rinse. Bath water contains skin oil and bacteria, and using it for the rinse too leaves the laundry smelling. If the bath contained a bath additive, check its packaging ("can be used for laundry", etc.).
- Feeding hot water into the machine: most fully automatic machines have an inlet-water limit of about 50°C. Ignore the manual and you risk degraded hoses and seals, or a breakdown.
- Undissolved detergent: in winter, powder detergent dissolves poorly at 5–10°C and may leave white residue. Switch to liquid, or dissolve the powder in warm water before adding it.
- If you use 60°C against mites, keep it to cotton sheets and towels whose label says 60 or above. A tumble dryer's hot cycle achieves a similar effect.
[Verify] Seasonal tap-water temperatures, mite-kill temperatures and machine inlet limits vary by region and model. Check the sources and the manuals of common models.
Misunderstanding 1｜"40" on the label means wash at 40°C
It is a maximum. Anything up to 40 is fine. Washing a "30" garment in 10°C winter water is no problem.
Misunderstanding 2｜A Japanese cold-water wash does not get clothes clean
Everyday soiling comes out perfectly well in water at around 20°C with detergent. Only items with skin-oil yellowing or smells need warm water, and only for the wash cycle.
Misunderstanding 3｜Using bath water for the wash and the rinse saves the most
Bath water in the rinse leaves skin oil and bacteria on the laundry. Rinse with tap water.
Misunderstanding 4｜With hot water I do not need detergent
Hot water only helps the detergent work; it is no substitute for the surfactants that break down skin oil.
Misunderstanding 5｜Hotter is cleaner, so 60°C every time
That leads to shrinkage, colour loss, creased synthetics and a broken machine. Keep 60°C for bedding, towels and other items that need it.
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Sources
- Consumer Affairs Agency (消費者庁), "The new care labels (JIS L0001): washing symbols and temperatures"
https://www.caa.go.jp/policies/policy/representation/household_goods/laundry_symbols/
- Japan Soap and Detergent Association (日本石鹸洗剤工業会), "Laundry basics: water temperature and cleaning"
https://jsda.org/w/03_shiki/
- Tokyo Metropolitan Government Bureau of Waterworks (東京都水道局), "Water quality data: water temperature over the year"
https://www.waterworks.metro.tokyo.lg.jp/
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
About this article
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
This is general information. Results vary from person to person and depend on your own conditions and surroundings.
Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.
Follow the care label and the maker's instructions for any garment, shoe or bag. For expensive or sentimental items, ask a specialist cleaner or repairer.
Sources
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