Japan is a mountainous island chain, which makes its water sources almost universally soft. When Japanese people travel abroad they are often surprised by the mineral sensation of drinking the hard water common in continental countries.
Water hardness is calculated by converting the amount of calcium and magnesium in water into calcium carbonate.
Less than 60 mg/L is considered soft,
60-120 mg/L medium-soft (or medium-hard),
120-180 mg/L hard,
and over 180 mg/L extremely hard.
The brewing water we use at Ippongi has an extremely low mineral content of just 27 mg/L, leaving even people who grew up with soft water reaching for more. The smooth mouthfeel of our ultra-soft water is key to its appeal.
Water can contain undesirable minerals that cause sake to discolor and make its aroma and flavor vulnerable to deterioration. The main two are iron and manganese.
Tap water in Japan can contain up to 0.3 mg/L iron (3 parts in 10,000,000)
and 0.05 mg/L manganese (5 parts in 100,000,000).
Brewing water is only allowed to contain 0.02 mg/L (2 parts in 100,000,000) of either.
Ippongi's brewing water contains less than 0.01 mg/L iron (1 part in 100,000,000),
and less than 0.005 mg/L manganese (5 parts in 1,000,000,000).
These values are so low as to be at the limit of detection.
This is the water that will eventually be transformed into Ippongi's sake.
The earth and roots
the golden landscape
The Okuechizen basin supplies all the water for the plain that stretches across the north of Fukui Prefecture. Upstream areas are heavily forested, so much so that the air itself carries the aroma of trees. Even in the height of summer, the rice fields are supplied with clear, cool groundwater.
The marvelous soil of Okuechizen is fertile and soft even at depth, able to cradle the roots of crops as they grow.
Nurturing this strong soil is the DNA of Okuechizen's farmers. All the rice straw from the harvest is dug back into the earth, both to level it and to renew the soil with nutrients released as the straw breaks down. This care to maintain soil quality has allowed the land to be passed down through the generations.
Fall scenes in Okuechizen are dyed in gold. And this scenery is supported by the foundation of earth and roots.
Why basins produce
The sun allows crops to grow by using photosynthesis to produce nutrients, which are then consumed by respiration at night. Low nighttime temperatures mean plants consume less nutrients, increasing the total amount available.
A 10°C (50°F) difference between daytime and nighttime temperatures is ideal for growing rice.
The beginning of August is a critical time for rice plant growth, and at this time of year Okuechizen has a day-night temperature difference of over 10°C (50°F). So the Okuechizen basin provides an ideal climate!