Onsen farting

For more than a thousand years the people of Japan have sought relaxation and healing in the waters of hot spring baths known as onsen. Today they are joined by visitors from around the world who have discovered the magical experience of bathing in the natural mineral rich waters of the Japanese onsen.

However, many foreign visitors are put off by the scent of rotten eggs that is often associated with these hot baths. They ascribe this smell to chemical reactions between the volcanic sulphur and the hot water deep beneath the surface of the Earth from where these waters are derived.

Steaming hot spring
Steaming hot spring waters

Today I would like to share with you the real reason that onsen waters smell as they do: The ancient Japanese practice that we can translate as “onsen farting”.

When one slips naked into the onsen bath, after first carefully scrubbing off all signs of dirt from their body, it is customary for a Japanese person to lie back, sigh contentedly and let one rip into the water.

They will continue to do so throughout their bath.

There are many good reasons to pass wind in the water. Not only does it release a scent into the bathhouse that is thought to clear one’s lungs and promote relaxation. The effervescent bubbles are believed to stimulate blood flow in the skin, whilst the release of pent up gases promote good gut health and prevent bloating.

The gas released has also been warmed up to around 37 degrees centigrade by the body, helping to keep the bath warm.

Finally, I am sure that we are all familiar with the feeling of satisfaction upon the release of a long pent-up fart.

As an esteemed Japanese poet once wrote:

A hot bath
Bubbles rise to greet
A satisfied belly


One need look no further than the Japanese symbol of the onsen for the association of water and the practice of onsen farting.

Onsen symbol with water and gas

The misconception about Japanese onsen farting amongst foreigners is understandable, considering the distaste and ridicule that such practices are held in the civilised cultures of the west and this is why it is traditionally not spoken about. However, I hope this article will give you a better understanding of Japanese culture and maybe you too will let one rip the next time you take a hot bath.

Hot spring chimneys
Chimneys release excess crusty farts from an onsen


Irreverently irrelevant. Sysadmin, developer, web dude in a science research agency. WordPress, Japan, planes, trains, Arduino, Raspberry Pi/Pico, puns, dad jokes, etc

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