While water of course plays an important role in all cooking, it can be said to have had a particularly strong effect on the development of Japanese cuisine.

A land of plentiful soft water
The abundance and variety of Japan’s natural resources have clearly played a central role in the development of the country’s cuisine. One of the most important elements when it comes to cooking, however, is the water that bubbles up from the country’s many springs, swells its rivers and, eventually, is used in so many types of food and drink. This water is not only replete with minerals and goodness acquired as it flows down Japan’s mountainous terrain, but compared with a good deal of the water to found elsewhere in the world, Japanese water is mainly soft.

Water and cooking
The hardness of water, as determined by the presence of minerals such as calcium and magnesium, can have a considerable effect on cooking. For example, the magnesium in hard water can impart a bitter, astringent taste to many foods, including meat, whereas soft water has a mild, sweet taste, and, more importantly, helps to bring out the flavour and aroma of other ingredients. This last point is particularly relevant in the case of Japanese stock or dashi, where soft water ensures that the flavours of the dashi ingredients, be they konbu kelp, bonito flakes or shiitake mushrooms, and those of other ingredients in the dish, are exploited to the full.

Water around the world
As shown in the chart below, Japanese water is, on the whole, softer than that found in many other areas of the world, particularly Europe and China. It is notable that while the US and Europe have certain soft water areas, Japan has soft water in all areas of the country, including the major cities of Tokyo, Osaka and Kyoto. This situation has almost certainly influenced cooking styles in each country, because while Japanese dishes such as dashi require soft water to achieve good results, western soup stocks for instance, and Chinese tang stock, can be made using hard water with no detrimental effect on flavour.

Water Hardness Around the World - Click the image to enlarge