A disk filter is a type of water filter

Filter (water)

A water filter removes impurities from water by means of a fine physical barrier, a chemical process or a biological process. Filters cleanse water to various extents for irrigation, drinking water, aquariums, and swimming pools.-Methods of filtration:...

 used primarily in irrigation, similar to a screen filter

Screen filter

A screen filter is a type of filter using a rigid or flexible screen to separate sand and other fine particles out of water for irrigation or industrial applications...

, except that the filter cartridge is made of a number of disks stacked on top of each other like a pile of poker

Poker

Poker is a family of card games that share betting rules and usually hand rankings. Poker games differ in how the cards are dealt, how hands may be formed, whether the high or low hand wins the pot in a showdown , limits on bet sizes, and how many rounds of betting are allowed.In most modern poker...

 chips. The water

Water

Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

passes through the small grooves in between and the impurities are trapped behind. Some types of disk filters can be backflushed in such a way that the disks are able to separate and spin during the cleaning cycle.