To prevent bacteria from growing in the activated carbon, the filter contains silver. According to the drinking water standards of some regions, such as Taiwan, and the Code of Federal Regulations (CFR) in the USA, the limit for silver in drinking water is 0.05 mg/L and 0.1 mg/L respectively. During filtration the filter releases a very small amount of silver, less than 0.05 mg/L, which is harmless to the human body.