There is a stone well in front of the Uchigura Sake Brewery, next to the Gekkeikan Okura Sake Museum. The water used to produce sake at this kura, or brewery, comes from fifty meters below the ground. Visitors to the Museum often say that they can sense a gentleness in this water, and that even in summer it remains cool and delicious.
Fushimi's groundwater includes the perfect amount of minerals dissolved into it from the granite layer, making it medium hard water with a hardness of 60-80 mg/L. The small amount of iron also makes it suitable for brewing sake. This pure water is the wellspring that gives birth to the smooth, mellow sake of Kyoto Fushimi.
The name Fushimi is written with the two characters 伏 (fushi) and 見 (mi). In the past it has also been written 俯見 using the characters 俯 and 見 to mean birds-eye-view, referring to the wonderful view seen from the Momoyama hills. The placename Fushimi already appears in the Nihon Shoki, or Chronicles of Japan, by the 8th century, the Manyoshu poetry collection from the 7th and 8th centuries, the Pillow Book from the 11th century, and the Shin Kokin Wakashu, or New Collection of Ancient and Modern Poems from the 13th century.
In the Edo period, the characters 伏水 (fushimi) were used, combining 伏 (fushi) and 水 (which means mizu, or water). This placename, referencing water, comes from the fact that south of Fushimi, which lies at the southern end of the Kyoto Basin, is an area which contains a lot of water, including the Ogura Pond, as well as the canal that ran through Fushimi to serve as the outer moat of Fushimi Castle, and the fact that Fushimi itself developed as a riverside trading town thanks to its ports where Sanjikkokubune (traditional medium boats to transport goods and people) arrived after travelling up the Yodo River. In addition, Fushimi has the thickest groundwater layer in the Kyoto Basin, and so this placename could be seen as symbolizing how all this groundwater keeps brimming up. But it's thanks to this wealth of water that sake breweries could concentrate in the area, letting Fushimi develop into one of Japan's prime sake-producing regions, with more than twenty brewers currently members of the Fushimi Sake Brewers Association .
Kyoto has been called the capital celebrated for scenic beauty, referencing its purple mountains and pure water. The mist rising from the earth makes the hills surrounding the basin seem purple. This mist becomes clouds, which return the moisture to the earth in the form of rain and snow. The rain that falls in the mountains the surround Kyoto to three sides filters through these forested hills and into the Kamo and Katsura rivers which flow through the city. The area around the To-ji Temple (the Kyoogokoku-ji Temple, Minami-ku, Kyoto) is about 50 meters lower compared to Kitayama-dori street at the north of the city. The river water flows down this gentle slope towards Fushimi in the southern area.
The flow of water from the north to the south is seen underground as well. In addition to water flowing in the rivers, it is also absorbed into the ground, gradually becoming stockpiled as groundwater. The rivers have changed their current time and again over the centuries, but a wealth of underground water remains underneath the old river channels as well.
Underneath the Kyoto Basin lies a vast reservoir of water, almost as large as Lake Biwa, that has been termed the Kyoto Suibon, or Kyoto Water Basin. Professor Hareshige Kusumi of Kansai University has announced that the Suibon contains 21.1 billion tons of water. Its scale reaches 12 km east-west and 33 km north-south, getting deeper towards the southern area, reaching its deepest at the location where Ogura Pond once lay (until it was finally completely filled in 1933), immediately to the south of Fushimi, where it hits 800 meter deep. This report both underscores how much the rich water supply of Kyoto has contributed to the development of industry and culture, as well as suggests it a major positive for future development.
The Katsura, Uji, and Kizu rivers merge and become the Yodo River where they are narrowed by Mt. Tenno and Mt. Otoko, flowing out into Osaka Bay. The aquifer under the Kyoto Basin, the Kyoto Suibon, is also believe to exit around here. The plain extending out on the right (south) side is the reclaimed land where Ogura Pond once lay. The sake town of Fushimi is immediately to its right (north).
The conditions for brewing water are stricter than the quality required for drinking water. The iron content must be no more than 0.3 ppm for tap water, while for sake-brewing water, it must be no more than 0.02 ppm. Fushimi's groundwater contains a mere 0.006 ppm. Iron binds with a substance called deferriferrichrysin which is created by the koji mold to become red-orange ferrichrysin, coloring the sake, so the idea is to have as little iron as possible. The sake brewing equipment must also avoid the use of iron in any parts that the sake will come into contact with.
When water is hard, the differences in the rock layers that the groundwater passes through become more clear. Water with a lot of minerals is called hard, while if there are few minerals it is called soft, and the degree of hardness is measured. The rock beneath Fushimi is made of granite, and this layer of rock adds a suitable amount of minerals such as calcium and magnesium to the water, making it moderately hard water with a hardness of 60-80 mg/L.
Using this water, and fermenting the sake for a relatively long time, creates a smooth, crisp, non-acidic dry sake. The quality of sake is not just influenced by the water: the cuisine also has a major impact. Fushimi's sake has been refined to go well with traditional Kyoto dishes, influenced by court cuisine and the vegetarian cuisine (shojin ryori) of Buddhist priests .