Large amounts of water are used at almost every step of the brewing process (ca. 30 times the volume of the finished product) and roughly 80% of a bottle of sake is H₂O. So it goes without saying that water quality plays an important role in defining the quality and character of a sake.

Sources and Uses

Breweries are therefore often located near naturally abundant sources of good-quality water in the form of underground water (springs, subterranean water) or rivers. There is even a saying, “Where there is good sake, there is always good water.” Distinctions are made between water used for brewing and bottling and for other processes where the water quality is not as important.

Brewing water (jozo yosui) is the water used for washing and steeping the rice and for the mash. In many breweries, this will be (filtered) water from a deep well or a natural spring.

Bottling water, the water that is added later to adjust the strength of the sake (and for rinsing the bottles before filling), should be of the same quality as the brewing water, but can come from a different source. Some breweries might also use distilled water free of any minerals for dilution to give the sake a softer character.

Water for steaming the rice also needs to be of good quality and without any off-flavours, but it doesn’t need to be as pure as the brewing water, so filtered municipal water can also be used. The same goes for the water used for pasteurising and other applications.

Lastly, a large amount of water, around half of the volume of all water used in a brewery, is needed for cleaning the equipment. Cleanliness is of utmost importance to avoid any chance of contamination of the sake.

Quality

Brewing water has to meet some strict requirements with regards to mineral content. While some minerals can be helpful during the fermentation, others produce off-flavours. Iron and manganese levels need to be especially low (less than 0.02mg/l).

Iron will lead to discolouration, an unpleasant taste and quick deterioration of the quality of the sake. Iron ions bind with a compound that is a natural product of koji and form a crystalline complex with a red-brown colour. Iron can be removed via aeration or other methods, and some breweries will do this in any case, just to be sure there is absolutely no trace of iron left.

Manganese helps to accelerate the chemical processes that occur when sake is influenced by UV-light, such as sunlight; the sake becomes ‘light-struck’ and develops a distinct unpleasant flavour and becomes discoloured. Naturally, the water also needs to be clean, i.e. free of organic matter, bacteria and other impurities.

Magnesium, calcium, phosphates, and potassium on the other hand help the fermentation by supplying nutrients for the yeast, especially during the starter phase, and the koji.

Water quality and mineral content can vary greatly, even within a small area. A well only a few meters from another source can contain water from a different underground stream with different minerals. There are stories of brewery owners digging for a long time before finding the water that suited their needs.

Hard & Soft Water

dH stands for ‘deutsche Härte’ or ‘German hardness’ and is a scale to measure water hardness that was used in Germany, Japan and a few other countries. With international standardisation, this unit has been replaced by mmol/l, but it is still used by some sake brewers. 1˚dh=0.178mmol/l

Water hardness is defined by the amount of minerals in the water, mostly calcium (Ca), magnesium (Mg) and bicarbonate (HCO₃). Japan generally has very soft water that is low in minerals. The national average is around 61mg of HCO₃ per litre or ca. 2.5˚dH (see note). The map below shows the average values for each prefecture.

For comparison, the tap water of Copenhagen, Denmark, is super hard at 18–24˚dH, Vienna and Zurich both have moderately soft water around 6–11˚dH, while Paris’ water is relatively hard with 14–17˚dH (values can vary because cities get their water from a mix of sources). Popular European mineral waters like Evian, Vittel or Contrex reach even higher values of over 80˚dH.

Water that would be considered ‘soft’ in Europe is still much harder than most water in Japan. This is due to geological differences: Europe has a lot of limestone which adds calcium to the water, while Japan’s rocks are mostly of volcanic origin and don’t provide many minerals. The large amount of rainfall also contributes to an overall softer water.

Brewers refer to hard and soft water as either ’strong’ or ’weak water’, because hard water will promote a faster, more vigorous fermentation while softer water means a slower fermentation.

A Tale of Two Cities

The excellent quality of Miyamizu was discovered in the 1840s by Tazaemon Yamamura, who owned two breweries. The brewery in Nishinomiya always produced sake that was superior to anything the other (in Uozaki) could make — no matter what he tried. Eventually, he transported the water from Nishinomiya to the other brewery and thus discovered the qualities of Miyamizu.

His brewery still exists, it’s Sakura Masamune.

Two water sources hold a special place in the sake world: Miyamizu from Nada and Gokosui from Fushimi.

Miyamizu, the ‘heavenly water’ from Nada (Kobe) is the most famous example of a ‘strong water’, which clocks in at 8˚dH. The water is rich in potassium (20 mg/l) and phosphate (5.2mg/l), which promote yeast growth. Good yeast growth means a faster, stable fermentation that results in a dry sake. A strong fermentation that progresses quickly also lowers the risk o contamination and spoilage, which was especially important in the old days.

The water of Nada is also naturally low in iron. As the water travels underground from the Rokko mountains, it flows through gravel. There it is mixed with oxygen; the iron becomes oxidised and forms insoluble compounds that are deposited along the way.

The quality of the water in Nada, together with the convenient location for shipping the finished product to Tokyo, is one of the reasons why the region became the largest producer of sake.

Japanese gin has become quite a trend. KiNoBi Gin from Kyoto Distillers is also made with Fushimi water.

Fushimi’s fragrant Gokusui (from the area in Kyoto that most tourists know for its shrine) is equally famous but softer at 4˚dH (although still ‘medium hard’ for Japan) and thus the sake from Fushimi is smooth and mellow, and slightly sweet. In the mid 1600s there were more than 80 breweries in the Fushimi area and today Kyoto is number two behind Nada in terms of production volume.

With the advent of ginjo-style sake, Saijo in Hiroshima Prefecture needed to be added to the list of famous sake-producing regions. Their soft water favours a slow fermentation which is necessary for the fruity ginjo aromas to develop. But until Senzaburo Miura discovered this new brewing method in 1898, Hiroshima’s water had actually been considered unsuitable for making high-quality sake.

There’s Something in The Water

It is now possible to apply for a GI, a protected Geographical Indication similar to the European system, for Japanese sake from Nadagogo, Yamagata or Hakusan (in Ishikawa Prefecture). The rules specify that the water has to be sourced in the area of the respective GI, but the rice can be from anywhere in Japan. That would imply that water is more important for the regional character of a sake than any other ingredient.

Many breweries will be quick to tell you how their water is very special and uniquely suited to producing the best quality sake. But those who are not blessed with an optimal source can use regular (filtered and purified) water and are allowed to add the necessary amounts of minerals and nutrients (e.g. potassium ions) to obtain a water that suits their brewing method and style of sake. Especially the water used for the yeast starter (shubo or moto) can be treated this way to guarantee that the fermentation gets off to a good start.

So while water certainly can play an important role in shaping the character of a sake and might even contribute something like terroir, it all comes down to the brewer’s decisions in the end. Some prefer a more technology-driven process and want to produce a beverage with a certain profile that matches a popular demand or just fits their personal idea of what a good sake should be, while others might be more willing to work with the raw materials their region has given them, even if they are limiting.

Some breweries employ water as an active tool and use different water sources for different products. Monten [門天], brewed at Usui Shoten in Nagano Prefecture, is one such example. Their Purple Label Junmai Ginjo is brewed with hard water from a spring beneath the northern Japan Alps and has a sharp and crisp taste, while the rest of their lineup is made with soft water sourced in the Iyari Wetlands National Park.

If you ever have the chance to taste a sake and the water it was brewed with side by side, you should take it! It’s always in interesting experience and you can try to find common characteristics in both.