Washing soda (sodium carbonate) is used for dishwashing, and may be used in areas with hard water. It was used for dishwashing before detergents were invented in Germany during World War I. Liquid detergent used for dishwashing was first manufactured in the middle of the 20th century. Dishwashing detergent producers started production in the United States in the 1930–1940s. Teepol, the first such in Europe, commenced production in 1942.