This Pentek 153070 #20 Big Blue housing sump fits caps for Pentek #20 Big Blue filter housings with any inlet and outlet size, and same size housing caps made by several other manufacturers. It is made of reinforced polypropylene for strength and resistance to chemicals. This sump meets National Sanitation Foundation/American National Standards Institute (NSF/ANSI) standard 42 for quality assurance, and is for use with Pentek #20 Big Blue housings, which are used in various applications, including residential drinking water filtration, food service, and humidifying systems, among others. Water filters remove undesirable particles, chemicals, and microorganisms from water by means of a semi permeable barrier, adsorption, or biological processes. For most residential, commercial, and industrial applications, water filters are manufactured in the form of replaceable cartridges that fit inside permanent housings. Filtration systems typically consist of a series of 2 or more types of filters, each designed to remove different contaminants. The performance of filters is measured by the minimum particle size that is blocked, the percentage of particles or microorganisms that are removed, the downstream concentration of unwanted chemicals, the maximum flow rate, and the amount of water that can be filtered before the filter must be replaced.