How does arsenic get into my drinking

water?

Arsenic occurs naturally in the environment and as

a by-product of some agricultural and industrial

activities. It can enter drinking water through the

ground or as runoff into surface water sources.

How is arsenic in drinking water

regulated?

In 1974, Congress passed the Safe Drinking Water

Act. This law directs EPA to issue non-enforceable

health goals and enforceable drinking water

regulations for contaminants that may cause health

problems. The goals, which reflect the level at

which no adverse health effects are expected, are

called maximum contaminant level goals (MCLGs).

The MCLG for arsenic is 0 parts per billion (ppb).

The enforceable standard for arsenic is a maximum

contaminant level (MCL). MCLs are set as close to

the health goals as possible, considering cost,

benefits, and the ability of public water systems to

detect and remove contaminants using suitable

treatment technologies.

Arsenic is a toxic chemical element

that is unevenly distributed in the

Earth’s crust in soil, rocks, and

minerals.

What is arsenic?

What is EPA’s standard for arsenic in drinking water?

To protect consumers served by public water systems from the health risks of long-term (chronic)

arsenic exposure, EPA recently lowered the arsenic MCL from 50 ppb to 10 ppb.

JUST THE FACTS FOR CONSUMERS

Why should I be concerned about

arsenic in my drinking water?

Although short-term exposures to high doses (about

a thousand times higher than the drinking water

standard) cause adverse effects in people, such

exposures do not occur from public water supplies

in the U.S. that comply with the arsenic MCL.

Some people who drink water containing arsenic in

excess of EPA’s standard over many years could

experience skin damage or problems with their

circulatory system, and may have an increased risk

of getting cancer. Health effects might include:

6 Thickening and discoloration of the skin, stomach

pain, nausea, vomiting, diarrhea, and liver effects;

6 Cardiovascular, pulmonary, immunological,

neurological (e.g., numbness and partial

paralysis), reproductive, and endocrine (e.g.,

diabetes) effects;

6 Cancer of the bladder, lungs, skin, kidney, nasal

passages, liver, and prostate.
What is a community water

system?

A community water system is a system that

serves 15 locations or 25 people year-round,

including most cities and towns, apartment

buildings, and mobile home parks with their

own water supplies.

What is a non-transient, noncommunity water system?

Non-transient, non-community water

systems serve at least 25 of the same

people more than six months of the year,

such as schools, churches, nursing homes,

and factories.

EPA 816-F-07-002

March 2007

Office of Ground Water & Drinking Water

www.epa.gov/safewater

What types of public water

systems must comply with the

standard?

The 10 ppb arsenic standard applies to all

community water systems. The standard

also applies to non-transient, noncommunity water systems.

How will I know if there is

arsenic in my drinking water?

Every year, your community water system

sends you a consumer confidence report

(sometimes called a water quality report),

listing any levels of arsenic detected. EPA

also requires all community and nontransient, non-community water systems to

give you public notice when their water

supply violates the arsenic standard. You will

be given information about what is being

done to correct the situation.

Should I have my water tested for arsenic?

If your water comes from a municipal or privately-owned water company

that has more than 15 service connections or serves 25 people more

than 6 months of a year, they are already testing for arsenic in your water.

If you have your own household water supply, you are responsible for

maintaining and testing it. Contact your local health department to find

out whether arsenic is a contaminant of concern in your area. Your state’s

drinking water agency can give you names of laboratories that are certified

to test drinking water.

NSF International (www.nsf.org/certified/DWTU), the Water Quality

Association (www.wqa.org), and the Underwriters Laboratories, Inc.

(www.ul.com/water) web sites list certified home treatment units.

How much is 10 ppb?

10 parts per billion (ppb) of

arsenic in water means that

there are 10 molecules of

arsenic for every

999,999,990 molecules of

water. That is roughly

equivalent to a few drops

of ink in an Olympic-sized

swimming pool.

FOR MORE INFORMATION Arsenic in drinking water

http://www.epa.gov/safewater/arsenic

Arsenic health effects

http://www.atsdr.cdc.gov/toxprofiles/phs2.html

Your private well

http://www.epa.gov/safewater/privatewells

Safe Drinking Water Hotline

1-800-426-4791

JUST THE FACTS FOR CONSUMERS