How Important is Water for Sake Brewing?

Did you know that sake is made up of approximately 80% water?

You may (probably not) have found yourself thinking: ‘So how important is it really to use good quality water when it comes to brewing sake? It can’t make that much of a difference, can it?’

This blog is here to answer - Oh yes it can.

The process of making sake is meticulously tailored and perfected at every stage. Each ingredient can make or break a sake. We won’t get into the nitty gritty biochemistry of it (we would be here all day), but water holds a great deal of importance when determining the fermentation style, flavours, body and even brewery location.

There are five ingredients that are allowed to be added to a sake for it to be legally defined as premium sake (the category of sake we offer in our portfolio): water, yeast, koji, rice and distilled alcohol (not for Junmai sake). They all interact, and this can get messy if not controlled. From a sake-brewing point of view, there are two types of water – hard and soft.

Hard water has higher levels of minerals, including calcium, magnesium, potassium phosphoric acid. The UK is particularly abundant with hard water (as we begrudgingly stare at the limescale in our kettles), to the point where the softest UK water is still in the same mineral content range as Japan’s hardest water. These minerals are important in sake brewing as they keep the yeast and koji happy, thus encouraging a more vigorous fermentation. The higher levels of minerals within the water contribute to a less aromatic, yet dry and robust profile, with many calling these styles ‘masculine sake’. A legendary example of hard water in Japan is Miyamizu, originating from Hyogo prefecture. The water was so famous for consistently producing full bodied and flavourful sakes, that visiting brewers would transport this water back to their own breweries to use. The nature of the hard water in this prefecture is said to draw out the savoury flavours of meat, which is ideal for the city of Kobe - already known for their high quality beef!

Soft water on the other hand has lower levels of these minerals, resulting in a very slow and gentle fermentation. This originally produced contaminated sakes because the lack of said minerals provided less natural protection against bacterial growth. Historically, this water posed many issues when breweries started using it, especially in Hiroshima prefecture, where natural access to hard water was…hard. Enter Senzaburo Miura, a sake brewer who revolutionised the brewing process by adding the ‘soft water brewing technique’ to the mix in the 1870s, which required a longer brewing time and lower temperature. Sake made from soft water has a more aromatic, fragrant profile, with generally mellower and sweeter characteristics.

Regardless of hard vs soft water, one mineral that is detrimental to sake is iron, which interacts negatively with the koji mould to produce a rusty colour. Therefore water needs less than 0.02 ppm of iron to be suitable for sake brewing. Fortunately due to technological advancements and filtration systems, consistently high quality water is more accessible to sake breweries today.

Hopefully this crash-course on water has given you a little bit more insight into just how minerality can impact sake. If you have the opportunity to travel around Japan, be sure to sample the distinct regional sakes and experience firsthand how their characteristics change based on the local water quality!