01 — Gassan Deep Water
Water
Polished by Mt. Gassan for 5,000 years
Gassan Deep Water
The Source
Snow that fell on Gassan
becomes sake 5,000 years later.
Three hundred metres beneath the brewery lies a bed of quartz gravel some 50 metres thick. Far upstream rises Mt. Gassan, one of Japan’s three great mountains.
Snow and rain on Gassan travel through the strata for roughly 5,000 years, polished by crystalline gravel under some 30,000 hPa of pressure, before reaching our well.
We draw it at 30 litres a minute — the natural pace the aquifer can sustain — and never more. 210,000 litres are kept chilled at all times, and this water alone is used at every stage of brewing.
In Numbers
Our brewing water, in numbers.
Schematic based on the brewery’s geological survey.
Natural Filter
Sealed above and below
by clay — a natural filter.
The brewery sits on the eastern Shonai plain, on the right bank of the Aka River, on an alluvial fan spreading north-west from Gassan. Clay loam, ash, pumice, gravel, silt and finally quartz gravel — sediments laid down over tens of thousands of years. Clay layers above and below seal the aquifer and protect the water.
Water Profile
Soft,
yet with contour.
At 19mg/L, the water is classed as very soft — yet most people who taste it notice a gentle structure.
That comes from its silica (39mg/L). Not merely soft, it is a water with contour, able to draw out the rice’s umami right to the end of fermentation. It is the backbone of Takenotsuyu’s sake.
- JIS hardnessVery soft (under 100 is “soft”)
- 19mg/L
- pHMildly alkaline
- 7.8
- Silica (ionic)Gives the water its contour
- 39mg/L
- SodiumA rounded mouthfeel
- 12mg/L
- CalciumGently supports fermentation
- 5.8mg/L
- MagnesiumFar below levels that add harshness
- 1.4mg/L
- PotassiumLeaves the rice’s own minerals alone
- 0.6mg/L
- Heating / electrolysis / adjustmentUsed exactly as drawn
- None
Bottled at the Brewery
Our brewing water,
bottled as it is.
The same Gassan deep water we brew with, bottled without heat sterilisation as a natural mineral water — in 1.8L and 720ml bottles. It makes clean dashi, soft tea and fragrant rice, and is the perfect chaser between sips of sake.
Available at the brewery shop.
Next: rice