The key to success lies in brewing tea leaves with cold water. Simply place your favorite tea in the filter, pour cold water over it, and put the bottle in the refrigerator. This brewing method allows for a smooth and rich flavor without bitterness. The filter keeps the tea leaves inside, ensuring a clear infusion. The Hario Mizudashi is made of high-quality glass with stainless steel and plastic elements. It is manufactured in Japan to the highest quality standards. Another advantage of the bottle is its ease of cleaning – it is dishwasher safe.