Why is the domestic bath water in Japan milky white?

White is the common color of sanitary ceramics in the world. White is clean, which obviously can judge whether it is clean or not, but it is not a hard and fast rule. Now there are some colored sanitary ware, but relatively few, which should be related to the hearts of consumers, just like doctors in hospitals wear white, giving people a clean and hygienic feeling. And in terms of home improvement, red and green are also difficult to match. Most people accept white, and white glaze has lower cost and stable hair color than colored glaze.