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[[Image:UV lamps.jpg|thumb|right|300px|In Bhupalpur, India, Ashok Gadgil's ultraviolet-light water purification system treats water from a public well. Photo: [http://web.mit.edu/invent/www/ima/gadgil_bio.html Ashok Gadgil.]]]

Two alternative configurations or physical systems are used for UV disinfection of small or household water supplies, submerged lamps or lamps in air and mounted above a thin layer of the water to be irradiated. In the units with submerged lamps, the lamps are covered with a protective, UV-penetrable as protection from the electrical hazards associated with water. Water can be treated on a batch basis by placing the lamp in a container of water for several minutes or longer, or on a flow-through basis in a housing or channel, with the water flowing parallel or perpendicular to the lamp(s).