A reagent reservoir is a laboratory container used to hold and dispense liquid reagents. It is commonly made of plastic and has a large, flat surface area and a volume ranging from several milliliters to liters. The reservoirs typically have a lid that can be opened for refilling or to add reagents, and a spout for dispensing the reagents into other containers.

They are used in various types of experiments and procedures, including cell culture, assays, and liquid handling, where a large volume of a specific reagent is needed. The flat surface area of the reagent reservoir allows for multiple wells to be filled at once, making it a convenient and efficient tool in the laboratory.