This law required addition of 83 contaminants by 1989, and required adding 25 contaminants to the list every 3 years thereafter. Examples of new standards from this law include various VOCs in water, and inorganics such as aluminum, nickel, and beryllium. The 1996 SDWA amendments canceled the schedule of 25 new standards every three years, and in its place set up a mechanism to set standards based on the occurrence and assessed risks of contaminants. 1 GPG is equal to 17.1 PPM of water hardness as defined by Standard Methods. If the hardness is over 3 GPG, softening can usually save enough to pay for the cost and maintenance of a water softener.
Water softeners can also remove copper, iron, and other minerals.
De-ionization is a more extensive form of water softening that removes anions as well as cations. ClO 2 must be generated on site no reliable test for the residual 3. If necessary, soda ash can be added to raise the pH. More typically, the pH naturally rises from the use of hypochlorites.