Alkaline Ionized Water Day (Arukari Ion Sui no Hi) — "0711" reads as "onaka ni ii," meaning "good for your stomach"

What Is Alkaline Ionized Water Day?

Every year on July 11th is "Alkaline Ionized Water Day" in Japan, established by the Alkaline Ionized Water Equipment Council. The date comes from a wordplay on "0711," which reads as "onaka ni ii" — meaning "good for your stomach" — a reference to alkaline ionized water's benefits for digestive health. The day encourages people to learn about the science behind water and to use that knowledge for health management during the hot summer months, when hydration becomes especially important.

A History of Medical Recognition

Alkaline ionizer machines are more than just home appliances — they have a history grounded in scientific verification.

• Approval by Japan's Ministry of Health: In 1966, Japan's then Ministry of Health and Welfare (now the Ministry of Health, Labour and Welfare) granted manufacturing approval for alkaline ionizers as medical-use water generators. This was an official acknowledgment of the effects that water produced through a specific electrolysis process can have on the body.
• Large-scale re-verification: In the 1990s, an "Alkaline Ionized Water Equipment Review Committee" was established to further confirm its effects through rigorous double-blind clinical trials, reconfirming its benefits for digestive symptoms.

The Science of Electrolysis

What sets alkaline ionized water apart from ordinary drinking water lies in how it's produced.

• Production through electrolysis: By passing a direct electric current through water inside the ionizer, hydroxide ions (OH-) and hydrogen gather at the cathode (negative electrode), producing water with a pH of around 9–10 that also contains dissolved hydrogen. This is the physical basis of alkaline ionized water.
• Effects on digestive symptoms: Drinking alkaline ionized water has been medically recognized to ease stomach discomfort and promote regular bowel movements. This is a scientific result of the water's alkaline properties interacting with stomach acid and the intestinal environment.

Fascinating Facts About Alkaline Ionized Water

• A hydrogen byproduct: During the electrolysis process, hydrogen is generated at the cathode. As a result, the water contains trace amounts of dissolved hydrogen, and research into "hydrogen-rich water" continues to this day.
• Better extraction for cooking: Alkaline water is better at drawing out flavors from ingredients — it can enhance tea brewing and help extract more umami-rich amino acids from dashi stock, offering real culinary benefits.
• Careful pH management: Based on official approval guidelines, alkaline water for drinking is recommended to stay within a pH range of 9 to just under 10. Water that's too alkaline could place strain on the body, so the concentration is carefully managed.
• Acidic water as a byproduct: At the anode (positive electrode), acidic water is produced at the same time. While not suitable for drinking, it has an astringent effect that makes it useful for skincare applications like washing your face.
• "Kangen water" gaining global recognition: Japan's precise electrolysis technology has become known internationally under names like "reduced water" or "kangen water," with Japanese expertise playing a role in supporting health infrastructure around the world.

Ideas for Alkaline Ionized Water Day

• On July 11th (Alkaline Ionized Water Day), take a moment to think about how well-hydrated you really are. Drinking water regularly — before you even feel thirsty — helps keep your blood from becoming too thick and can help counter the mental fatigue that builds up at the start of a new fiscal year.
• Try making dashi stock with alkaline ionized water and compare the flavor to tap water. Tasting the difference is a great way to experience firsthand how the chemical properties of water affect cooking.
• Listen to what your body is telling you. If the stress of the new fiscal year has left your stomach feeling heavy, consider the recognized digestive benefits of alkaline ionized water as a starting point for some thoughtful self-care.
• Clean or replace your ionizer's filter. Keeping it well-maintained is the most basic — and most important — way to ensure you're consistently getting safe, high-quality water.

Caring for the Water That Makes Up About 60% of Your Body Awakens a Refreshing Vitality from Within and Carries You Toward a Healthier Tomorrow

July 11th is a day to rediscover the potential of water — the very source of life. Just as the wordplay suggests, taking care of your stomach is closely tied to taking care of your whole body. If the busyness of the new fiscal year has caused you to overlook your own well-being, today is the day to slowly drink a full glass of water and savor the feeling of it spreading through your body. The power of water, refined through science, can help you feel lighter and healthier — so step into summer with a clear mind and a refreshed body.