The US has set steep import duties on Chinese chemicals used in sanitizing water after finding the products were being sold too cheaply.

In a preliminary decision, the Department of Commerce set anti-dumping duties of 210.52% on Chinese imports of calcium hypochlorite, used in chlorinating and sanitizing water.

Companies expected to be hit by the duties include China Petrochemical International, a subsidiary of Sinopec, Tianjin Jinbin International Trade and Wuhan Rui Sunny Chemical Co.

The complaint was brought by Arch Chemicals, a subsidiary of Swiss chemical producer Lonza. In 2013, imports of calcium hypochlorite from China to the US were valued at around $8.1 million.

The decision is subject to final rulings from the commerce department, due by Nov. 28, 2014 and the US International Trade Commission, due by Jan. 12, 2015.