Onsen: Benefits of Alkaline & Acidic Hot Springs
Have you ever heard there are five types of Onsen (温泉) hot springs in Japan defined based on pH values by Japan’s Ministry of Environment?
For those who don’t know about this, they are as follows.
| pH values | Types of Onsen |
|---|---|
| pH8.5 or above | Alkaline Onsen |
| pH7.5 to pH8.5 | Weak Alkaline Onsen |
| pH6.0 to pH7.5 | Neutral Onsen |
| pH3.0 to pH6.0 | Weak Acidic Onsen |
| pH2.0 to pH3.0 | Acidic Onsen |
Benefits of Alkaline & Acidic Onsen
Each Onsen listed above has its characteristic properties, but today, I will only talk about the difference in benefits between alkaline and acidic hot springs.
Now, let’s get started with Alkaline Onsen.
Alkaline Onsen (pH7.5 or above)
In addition to dissolving sebum on the skin’ surface, alkaline hot spring water softens keratin and can smoothen skin texture.
For that reason, many alkaline Onsen hot springs in Japan are called Bijin no Yu (美人の湯), loosely meaning Hot spring for making you more beautiful.
However, if the pH value of an alkaline hot spring is high, that can cause dry skin.
Therefore, after soaking in a strongly alkaline Onsen bath, it is better to have a shower to wash away components from the hot spring water.
Acidic Onsen (pH2.0 to pH6.0)
Tamagawa Onsen (玉川温泉)
On the other hand, Onsen, with low pH values, has sterilizing power and may give your skin a tingling sensation, but the acidic water works well for chronic skin diseases such as athlete’s foot.
However, soaking in a strongly acidic Onsen bath can cause rough skin. Therefore, as with the case of Alkaline Onsen, it is better to take a shower after bathing to remove its components from your body.
Incidentally, speaking of acidic Onsen, Tamagawa Onsen/玉川温泉, a hot spring resort in Akita Prefecture, is especially famous in Japan.
(Reference Page: Tenseien.co.jp)
