A Sand Filter is used to purify water. The Sand Filter consists of layers of sand arranged with coarseness of texture increasing downward that trap impurities in the water. The first documented use of a sand filter used for water purification dates to 1804 in Paisley, Scotland.
There are three main types of sand filters; rapid or gravity sand filters , upflow sand filters , and slow sand filters.
All three sand filter methods are used extensively in water purification throughout the world. The first two sand filter methods require the use of chemicals to work effectively while a slow sand filter can produce very high quality water free from pathogens, taste and odor without the need for chemicals.
A common consumer use of a sand filter can be found in many backyard swimming pools. The Sand filter is known to be the lowest maintenance of the three types of swimming pool filters. You may only need to open up the tank of a swimming pool sand filter every 6 years or so. On the other hand, DE pool filters require annual maintenance removing and cleaning the internal grid assembly, and cartridge pool filters don't backwash, you must remove the cartridge and clean the cartridge every so often, depending on the cartridge filter size. Sand filters are the easiest to operate and maintain.