VOS a.s. Písek, whose full name is Vodohospodářské strojírny a slévárny, was a manufacturer of machinery and castings for water management technology.

The roots of the factory can be traced to the foundry industry that developed in Písek in the late 19th century. In 1912, a factory called Rourovna began operating at the site, and in 1934 production was expanded to include machinery. The factory was nationalized in 1945, and as part of the reorganization of the industry, a factory called Vodohospodářské strojírny n.p. Písek was established in 1978.

In 1992, VOS a.s. Písek was established and operated under the name Vodohospodářské strojírny a slévárny a.s. Production ceased in 2008, and the company is now mainly engaged in managing and leasing the former factory premises.