Though you can drink the tap water In Japan, many varieties of particular water for people which stick to water are sold in recent years. 

People have often gone to get natural water everywhere of Japan bringing with a water tank to seek water called the best water from the old days. 
In recent years, there is an alkaline ionized water server at a special corner near the counter of the supermarket; you can get it cheaply in the member price. 

It is because the interest in water is increasing.
Many people are getting to prefer rather the water that has been said to be good for health and beauty than tap water containing chlorine. 
And such water is sold very much.

Hydrogen water that is good for beauty and has a detox effect is popular at the gym.
Besides, there are lined carbonated water, deep sea water and reduced water at shops.

Also, many people have put the water server in private homes because they want to drink favorite water easily at any time. 
Some people, who have no space to put a water server at home, have put the purification system to a water faucet. 

Water quality standard items (Water Supply Act Article 4, 50 items) in Japanese

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