The most common types of domestic water water purification systems consist of:
- Filtration Systems: A water filter is a device which removes impurities from water by means of a physical barrier, chemical, and/or biological process. Basic filters usually are porous beds of insoluble material. Other examples include cast forms, plates of sheet material, synthetic membranes, finely perforated plastic or specially sized beds of inert particles. Suspended silt, clay, colloids, and some microorganisms are removed by the filtration process. The ability of a filter to efficiently screen out particles depends on the size of the filter area, the quality of the water to be filtered, the required flow rate of the water, the design capacity of the filter, and its porosity. Filters are generally used for particles less than 0.0029 inches (0.07 millimeters) in diameter.
- Reverse Osmosis: Reverse osmosis uses man-induced pressure to force water through an extremely fine filtration membrane, removing up to 98% of dissolved ions. Reverse osmosis has become one of the most cost-efficient technologies to deionize water, and is capable of removing very small particulates down to 0.0001 micron in size, including most organic carbon or TOC (Total Oxidizable Carbon).
- Water Softeners: As groundwater dissolves limestone over time, calcium and bicarbonate ions are released into water. The measurement of the amount of limestone dissolved in water is termed “hardness." Conventional water softening uses a synthetic polymeric (plastic) material in the form of very small beads called an ion exchange resin to remove hardness from water.
- Distillation Systems: Distillation is a process in which impure water is boiled and the steam is collected and condensed in a separate container, leaving many of the solid contaminants behind.
- Disinfection: Disinfection is a physical or chemical process in which pathogenic microorganisms are deactivated or killed. Examples of chemical disinfectants are chlorine, chlorine dioxide, and ozone. Examples of physical disinfectants include ultraviolet light, electronic radiation, and heat.