Wallace & Tiernan Company was founded in 1911 by Charles F. Wallace and Martin F. Tiernan in New York City, New York. Its industry was chlorine feeder equipment and its headquarters were in New York City, New York (1911-1921) and Belleville, New Jersey (1921-1996).
Operations were moved to Vineland, New Jersey afterwards. In 1969 the firm merged with the Pennsylvania Salt Manufacturing Company, forming the Pennwalt Corporation with Wallace & Tiernan operating as a division. In 1989 the division was spun off and was purchased by North West Water plc (later renamed United Utilities) in 1991. The equipment manufacturing operations of United Utilities were acquired by the US Filter Corporation in 1997. US Filter was acquired by the Siemens Corporation in 2004, its name later changed to Evoqua Water Technologies.
- Wallace & Tiernan Canada, Ltd. (est. 1920) (Toronto, Ontario)
- Wallace & Tiernan Ltd. of London (est. 1926)
- Wallace & Tiernan Pty., Ltd. (est. 1954) (Sydney, Australia)
- Chlorine Control Apparatus