27. I heard that pH can be a problem. Do you ever need to adjust the pH for the arsenic treatment system to work well?

  • It is much harder for arsenic treatment systems to remove arsenic when the pH of the water is greater than 8.5, and at high pH the life of the arsenic treatment media is greatly reduced.
  • In New Jersey wells with arsenic and a pH greater than 8.5, a pH adjustment tank should be included in their system.  This can be accomplished by installing an anion exchange system before the arsenic tanks. The anion exchange system will reduce the pH about one point. The anion exchange system may also remove some arsenic which will also help increase the life expectancy of the arsenic treatment media, but as we note in FAQ 16 we strongly recommend against relying on an anion exchange system to remove arsenic.
  • Well water with arsenic and pH greater than 9.5 is a more difficult situation that will require the attention and recommendation of your water treatment professional.  Injection of ascorbic acid into the water before it goes into the arsenic tanks is one example of an approach for dealing with very high pH water.