Dealkalization, sulfate, nitrate, selenium, arsenic, and uranium can all be removed by anion exchange. These substances are all present as anions. The most common process is to use salt (NaCl) regenerated strongly basic anion exchange resins operating in the chloride cycle. The design of the equipment is essentially the same for any of these substances. Only the throughput capacities and the resin volumes are different because of the differences in relative affinities and concentrations. Those substances with high affinities can continue to load to higher concentrations on the resins by displacing others previously exchanged but with lower relative affinities.

The gel-type strongly basic resins whose functional groups are based on either trimethylamine (these are called type I) or dimethylethanolamine (these are called type II), have the approximately same order of affinities for the common ions found in potable water except for the hydroxide ion, which is not a factor here, and perchlorate. When operated in the salt cycle, the regeneration efficiency is about the same for both types.

The general order of affinities for both types of strongly basic resins for the common ions found in water at less than 500 ppm total dissolved electrolytes is

Ion exchangers using strong base resins that are regenerated with NaCl are commonly referred to as anion softeners because of the similarity of the equipment to the traditional cation-based water softeners. When the pH of the resin is at or above 7, anion resins tend to give off fishy odors.