EcoWater Spokane

Spokane's Ecological choice for fresh water

Arsenic in Well Water

What is arsenic?

Having arsenic in well water is common in private wells. Arsenic occurs naturally in rocks and soils in many parts of the county. Arsenic is used for a variety of purposes within industry and agriculture. It is also a byproduct of copper smelting, mining, and coal burning. Arsenic can combine with other elements to make chemicals used to preserve wood and to kill insects on cotton and other agricultural crops.

Where and how does arsenic get into drinking water?

Arsenic can enter the water supply from natural deposits in the earth or from industrial and agricultural pollution. Some industries in the United States release thousands of pounds of arsenic into the environment every year. Once released, arsenic remains in the environment for a long time. Arsenic enters the ground water when water percolates downward from the surface and contacts dissolved minerals containing arsenic. It is widely believed that naturally occurring arsenic dissolves out of certain rock formations when ground water levels drop significantly.

Arsenic is removed from the air by rain, snow, and gradual settling. Once on the ground or in surface water, arsenic can slowly enter ground water. High arsenic levels in private wells may come from certain arsenic containing fertilizers used in the past or industrial waste. It may also indicate improper well construction or overuse of chemical fertilizers or herbicides in the past.

Although arsenic is historically known as a notorious as a poison, in trace amounts it has been linked to cancer. On January 22, 2001 US EPA lowered the maximum contaminant level of arsenic in drinking water from 50 ppb to 10 ppb. Public water systems must comply with the new 10 ppb drinking water standard for arsenic by January 23, 2006.

How can I find out whether there is arsenic in my drinking water?

If you suspect a problem and your drinking water comes from a private well, EcoWater Spokane will test your well water for you free of charge.

How do I remove arsenic from my drinking water?

Heating or boiling your water will not remove arsenic. Because some of the water evaporates during the boiling process, the arsenic concentrations can actually increase slightly as the water is boiled. Additionally, chlorine (bleach) disinfection will not remove arsenic.

You may wish to consider water treatment methods such as reverse osmosis, ultra-filtration, distillation, or ion exchange. Typically these methods are used to treat water at only one faucet.

Contact EcoWater Spokane to find out which treatment options are available for your specific water treatment needs. Remember to have your well water tested regularly (hyperlink to water test opt-in), at least once a year, to make sure the problem is controlled.

Maximum Contaminant Level: 0.01mg/L (10ppb), Health Hazard

Recommended Treatment System:

  • Option 1 – Whole Home (POE) EcoWater ETF 2100-AS Series Filter
  • Option 2 – Reverse Osmosis (POU) requires pretreatment w/chemical feed of oxidizer