What can I do?

 

The USEPA and Ohio Department of Health suggest that owners of private wells with elevated arsenic use an alternate source of water for drinking and cooking, or install a water treatment system that reduces arsenic concentrations.

Water treatment for arsenic in private wells

Treating water for arsenic is not simple. Common household water-treatment methods, such as water softeners, activated carbon filters, and sediment filters are not effective for removing arsenic from water. Arsenic cannot be removed from water by boiling.

In Ohio, groundwater with elevated arsenic is relatively difficult to treat because it contains a large portion of As(3) more

There are two forms (or “species”) of arsenic—As(3) and As(5).

  • As(3) is also referred to as As(III), trivalent arsenic, or arsenite.
  • As(5) is also referred to as As(V), pentavalent arsenic, or arsenate.

These two species have different characteristics; As(5) has a negative charge, whereas As(3) has no charge. Because As(3) is uncharged, it is more difficult to remove from water than As(5). Some water treatment methods only remove As(5). Other methods can remove both types of arsenic, but are less effective at removing As(3).

In Ohio, As(3) is the predominant species in groundwater with elevated arsenic.

Arsenic species in samples of Ohio groundwater

Methods for removing arsenic from water include adsorptive media, reverse osmosis, distillation, and anion exchange. These methods can be used in 2 different types of systems:

  • Point-of-use (POU) systems treat water from a single tap. They are often installed in the kitchen, and treat only the water used for drinking and cooking—usually a few gallons per day.
  • Point-of-entry (POE) systems treat all of the water that enters a home—usually 250 or more gallons per day.

Methods for removing arsenic from water include adsorptive media, reverse osmosis, distillation, and anion exchange.

Six treatment options are discussed, with a focus on reducing concentrations of As(3).

Pretreatment

The effectiveness of most treatment methods depends on the chemistry of the water being treated. Groundwater chemistry varies across the U.S., and therefore, the effectiveness of arsenic treatment methods can also vary. For Ohio groundwater, pretreatment is usually recommended to increase the efficiency and lower operating costs of most arsenic treatment systems.

  • One form of pretreatment converts As(3) to As(5). more

    There are two forms (or “species”) of arsenic—As(3) and As(5).

    • As(3) is also referred to as As(III), trivalent arsenic, or arsenite.
    • As(5) is also referred to as As(V), pentavalent arsenic, or arsenate.

    These two species have different characteristics; As(5) has a negative charge, whereas As(3) has no charge. Because As(3) is uncharged, it is more difficult to remove from water than As(5). Some water treatment methods only remove As(5). Other methods can remove both types of arsenic, but are less effective at removing As(3).

    As(3) is the predominant species in groundwater with elevated arsenic.

    Arsenic species in samples of Ohio groundwater

  • Another form of pretreatment removes iron, which can “foul” or clog up arsenic treatment systems.more

    In Ohio, elevated concentrations of arsenic and iron occur together. Water softeners can remove iron from water, but not arsenic. This is because dissolved iron has a positive charge, whereas dissolved arsenic has a negative or neutral charge (depending on the “species” of arsenic present).

Comparison of pretreatment options

Installation guidelines

Installation of a whole-house (POE) system is considered to be alteration of a private well, so it is necessary to obtain a permit from the local health department. Point-of-use systems do not require a permit, but installation should follow local plumbing codes. Recommendations and requirements from the Ohio Department of Health are summarized here:

Installation guidelines from the Ohio Department of Health