Clean hold time (CHT)

The maximum time cleaned, and where relevant sterilized, equipment may be stored before use while it is still considered clean. Beyond that time microorganisms may grow or the equipment may be recontaminated, so it must be cleaned again before use. The limit is established during cleaning validation together with the storage conditions, such as drained, dried or closed. Japanese cleaning SOPs and validation reports usually state it next to the dirty hold time.