According to , contractual requirements for the hardness of posttreated DSWs for Ashkelon, Palmachim, and Hadera plants were the following: >60, 75-100, and 80-120 mg L -1 (as CaСO3), respectively . In 2008, the Ashkelon water's actual hardness was determined to range from 90 to 110 mg L -1 . Our median values of water hardness for the samples from Ashkelon, Palmachim, and Hadera plants were 72.9, 72.3, and 84.2 mg L -1 , respectively, which agree with the specifications.