Exploring the Potential of Water in Sake Terroir: A Yamanashi Prefecture Water Quality Research Project

Water is a critical component in the production of sake, comprising approximately 80% of its ingredients. Many brewers underscore the unique role of water in sake-making, distinguishing it from wine, which is made without the use of water. While rice can be transported over long distances, the vast quantities of water required for brewing make it impractical to move, meaning the availability of high-quality water has historically been a key factor when selecting a brewery location.

However, discussions surrounding water’s regional characteristics are often limited to its hardness—whether it’s soft or hard water—leaving much unknown about the specific qualities of water in different regions. To address this gap, the Yamanashi Prefecture Sake Brewers Association launched a comprehensive water quality research project from 2023 to 2024. Spearheaded by a team of geologists, the project delved into the geology of Yamanashi Prefecture to explore how it influences the water used in sake production.

To what extent can the relationship between local water sources and the character of sake be scientifically traced? In this article, we explore the findings of this groundbreaking research and examine how regional water quality shapes the unique terroir of sake.

Where does the brewing water come from?

Many sake breweries that produce local varieties rely on nearby spring or well water for their brewing process. This water, stored underground, acquires its unique characteristics from the geological layers and bedrock it passes through, which directly influence its taste and mineral composition.

However, the fact that water is bubbling up in a brewery’s garden doesn’t necessarily mean it originated there. To truly understand the nature of the water, it’s crucial to trace where it originally came from and how it traveled to its current source.

The Yamanashi Prefecture water quality survey for sake brewing was led by geologist Kenichiro Hisada, who has a long history of expertise in this field. In 2021, he played a pivotal role in the National Tax Agency’s project titled “Terroir Branding through Systematization of Water Quality Analysis of Sake Brewing Water Corresponding to Geology.” As part of that effort, Hisada analyzed 283 water samples from sake breweries nationwide, revealing the causal relationship between geology and water quality.

For GI Yamanashi sake, designated in 2021, only water from six specific water systems can be used. These systems are located at the southern foot of the Southern Alps, the northern foot of the Yatsugatake Mountains, the northern foot of the Chichibu Mountains, the northern foot of Mt. Fuji, the Fuji-Misaka area, and the northern foot of the Misaka Mountains. However, Hisada points out that even within the same water system, water quality can vary depending on location. Identifying the source of groundwater and the recharge area (*) is key to understanding these differences.

One method to pinpoint the origin of groundwater and its recharge area is by analyzing the dissolved ion content. In this Yamanashi project, the geology of the prefecture was categorized into four main regions based on their formation: (1) the accretionary prism area of the outer belt of southwest Japan, (2) the sedimentary rocks area due to the impact of the Izu Peninsula, (3) the plutonic rocks (granite) outcropping area in the southern Fossa Magna, and (4) the volcanic rocks outcropping area in the southern Fossa Magna (see Figure 1). Water from several springs and rivers in each of these areas was analyzed, as well as the brewing water from 12 sake breweries, to determine which geological features influenced the water in each case.

(*) Recharge area: A river area that is the source of water that seeps underground and supplies it to aquifers.

Diverse water quality due to complex geology

Yamanashi Prefecture is situated within a significant geological feature known as the "Fossa Magna," a large rift valley running through the center of the Japanese archipelago. This rift extends from Itoigawa in Niigata Prefecture, through Lake Suwa in Nagano Prefecture, cutting across Yamanashi, and continuing into Shizuoka Prefecture. A major portion of Yamanashi falls within this geological zone, making it a key region for studying the geological influences on water used in sake brewing.

The Japanese archipelago was once part of the Eurasian continent, but it separated around 22 million years ago as the Sea of Japan expanded. This tectonic shift also led to the formation of the Fossa Magna, a large rift valley. The "Southern Fossa Magna," which includes Yamanashi Prefecture, was subsequently shaped by repeated collisions with volcanic islands. According to geologist Kenichiro Hisada, the geology of this region is incredibly complex, with no comparable geological structure anywhere else in the world.

In Yamanashi, where the geology is highly complex, the water quality reflects this diversity. According to Mr. Amano, representative of Sasaichi Shuzo in Ohtsuki City, a world-renowned sommelier once tasted their brewing water and remarked, “There are three distinct flavors in this water. I’ve never tasted water like this before.”

At Sasaichi Shuzo, the brewing water is so mineral-rich that, at one point, they were advised to filter it in order to produce a more traditional "refined, dry" sake. However, the sake crafted with this water, which has a layered and complex flavor, has gained recognition overseas as a suitable alternative to red wine when paired with meat.

Geologist Kenichiro Hisada explains that the area where Sasaichi Shuzo is located, in the northeastern part of the Misaka Mountains, can be divided into three geological zones, as outlined in Figure 1: (1) the accretionary prism area of the outer belt of southwest Japan (composed of mudstone and sandstone), (2) the sedimentary rocks area due to the impact of the Izu Peninsula (andesite, a type of volcanic rock, is exposed) and (3) the volcanic rocks outcropping area in the southern Fossa Magna. The sommelier may have detected these three different flavors in the water, which passed through these distinct geological strata.

While this remains a hypothesis, exploring the relationship between geology and water quality could further enhance the sensory evaluation of sake, opening up possibilities that are yet to be fully understood.

The potential of water to unlock terroir

In relation to this project, a talk session was held on July 13th 2024 at the “Bishu Biken Yamanashi Seminar,” featuring a discussion between geologist Kenichiro Hisada and Mr. Amano, the representative of Sasaichi Shuzo.

During the talk, Mr. Hisada remarked, “There is a possibility that Yamanashi was the birthplace of Japanese liquor.”

In the Middle Jomon period, around 5,000 years ago, the Yamanashi-Nagano area flourished as a major trading hub for obsidian, and it is believed that about a quarter of Japan's population lived there. In 2018, the region’s rich cultural history was recognized as a Japan Heritage site under the title “The Jomon World of the Starry Central Highlands: A Journey to Meet Obsidian Mines and Jomon People Thousands of Years Ago.” Numerous artifacts, including pottery, have been unearthed from this region, and some of these vessels are thought to have been used in the production of fruit-based alcoholic beverages.

Traditionally, Yamanashi Prefecture has produced relatively little rice, and the conditions for GI Yamanashi sake only require that the rice used be “domestic rice of at least third grade.” Despite these less-than-ideal conditions for sake production, the conversation explored why sake continues to be produced in Yamanashi from various perspectives.

The event attracted top sommeliers from around the world, and Master of Wine Kenichi Ohashi delivered a lecture on Yamanashi wine. The event concluded with a tasting session, where a long line formed as attendees eagerly compared the brewing water from each sake brewery, highlighting the strong interest in the role water plays in sake production.

In recent years, as Japanese sake has gained popularity worldwide, more sake breweries are marketing their products with a focus on "terroir," a concept traditionally associated with wine. However, unlike wine, which is made from a single ingredient—grapes—where the growing environment is central, the factors contributing to the regional characteristics of sake are far more complex. Some question whether the concept of terroir can be applied in the same way to sake.

In wine, terroir refers to the natural environment where the grapes are cultivated, with soil and geology being key components. While the concept of terroir in sake is still evolving, future discussions about the regional characteristics of sake may need to include a deeper understanding of the water source, particularly its relationship to the area’s geology.

References

• Sake Business Laboratory, “Bishu-Biken Yamanashi” project report, (Viewed on August 15, 2024)
• Suntory, サントリーのエコ活 第3回 “水の世紀”を担う子供たちにこそ知ってもらいたい 『水の知』最前線 [Suntory's Eco-Activities, Part 3: “The Cutting Edge of Water Knowledge” - Something that we want children, who will be responsible for the “century of water,” to know.] (Viewed on August 15, 2024)
• Kenichiro Hisada, et al., 日本酒仕込み水の水質と地質 [Water quality and geology of the water used to make sake], The Geological Society of Japan, 128th Annual Meeting, 2021
• Groundwater Management Promotion Platform, 地下水の基礎 [Basics of Groundwater] (Viewed on August 15, 2024)
• Akito Kanazawa, et al., 山地源流域における湧水の涵養域の推定 [Estimation of the recharge area of spring water in the headwaters of a mountainous region], Journal of Japan Society of Hydrology and Water Resour, 34-2, 2021