Arsenic in Drinking Water

Arsenic in Drinking Water

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	Arsenic has recently become more of a concern in drinking water. Typically, arsenic would affect private water sources (private wells) more than public water systems. It doesn’t take much arsenic to contaminate a water supply
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Does your drinking water come from a private well? If so, how long has it been since the water was tested? Furthermore, did the last test include a test for arsenic? You should have quick, certain answers for all of these questions. As a homeowner with a private well, you have the responsibility of being sure the water is safe. You should have the water tested annually. If you are in an area where there is new construction going on, more frequent tests are recommended.

Arsenic has recently become more of a concern in drinking water. Typically, arsenic would affect private water sources (private wells) more than public water systems. It doesn’t take much arsenic to contaminate a water supply.

For public water systems, the Environmental Protection Agency (EPA) has established a maximum contaminant level (MCL) of 0.05 mg/L (milligrams per liter) for arsenic. In the future, the EPA is expected to lower the MCL for arsenic. In public water systems, these limits are closely monitored and maintained by the utility responsible for the system, usually the local water district. In private wells, however, there is no active monitoring or enforcement of these standards except when you, as the homeowner, initiate your own tests or when the property is sold. At the time of sale, many states require water tests.

Currently, some states, through their own environmental protection agencies or departments of health, have established lower levels (MCL) for arsenic, some as low as 0.01 mg/L.

In rural areas, some estimates indicate that the current EPA MCL (0.05 mg/L) is exceeded in about 10% of private wells. The lower level (0.01 mg/L) may be exceeded in 30% of private wells.

Thus, if you have a private well, you may have unsafe levels of arsenic. A simple test will put your mind at ease if the level is below the MCL. If it’s above it, you can do something about it. In either case, you will know what you are dealing with.

Arsenic gets into the water from soil and bedrock containing naturally occurring arsenic. There are also instances caused by human neglect regarding treatment of certain crops. Apple orchards, in the past, have used arsenic compounds for various types of disease and insect infestation control. These materials are now illegal. However, some of them may have built up sufficient accumulations in the soil to affect private wells.

The effect of arsenic in well water in cases that it exceeds the EPA’s MCL is an increased risk of cancer. This is the result of drinking the water, NOT of absorption through the skin. In other words, using the water for bathing is safe; drinking it is not.

For a private water system that has a high concentration of arsenic, a reverse osmosis system is the most common and cost-effective way of controlling it. Essentially, this system neutralizes the arsenic by forcing the contaminated water through a semipermeable membrane that captures the arsenic. This is an effective and relatively straightforward system.

Testing for arsenic should be done both before and after such equipment is put in place and should be done on a regular basis (at least annually) to confirm the equipment continues to operate properly.

For water testing, check the yellow pages in your area. Look under “Water”. Ideally, you should use an independent testing company. Then, after you have the results, you can talk to a company that handles water treatment equipment. If you use a company that sells and installs equipment to do the tests, you may compromise the objectivity of the results.

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