Highly sulfated high basicity polyaluminum chlorosulfate compositions that can be made by mixing dry aluminum hydroxychloride with a solution of aluminum sulfate or by diluting a dry mixture of aluminum hydroxychloride and aluminum sulfate with water. The present invention is directed to polyaluminum chlorosulfates (PACSs) that are high in basicity and that have a high percentage by weight of sulfate. The invention includes methods of using the PACS formed by these procedures in the treatment of water as well as packages containing dry aluminum hydroxychloride and aluminum sulfate as either separate components or as a mixture.
