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Q: Freshwater that contains Arsenic ( Answered,   1 Comment )
Subject: Freshwater that contains Arsenic
Category: Science > Earth Sciences
Asked by: djo-ga
List Price: $10.00
Posted: 07 Jun 2005 08:14 PDT
Expires: 07 Jul 2005 08:14 PDT
Question ID: 530359
What is the percentage of freshwater in the United States that contains Arsenic?

Request for Question Clarification by pafalafa-ga on 07 Jun 2005 12:59 PDT

One answer to your question is: "All of it"!

Arsenic is a naturally occurring substance, and all water sources can
reasonably be expected to have some arsenic in them, even though the
amounts may be immeasurably small -- parts per trillion or parts per

If you let us know a bit more about your interest in this question,
perhaps we can narrow down the information for an answer.  For
instance, as the comment (below) notes, there's a big difference
between the presence of arsenic, and the presence in amounts that
violate prevailing standards and might be considered dangerous.

Are you asking about the number of water systems that exceed arsenic standards?

Let us know.


Clarification of Question by djo-ga on 07 Jun 2005 14:26 PDT
Our company has a break through product that eliminates Arsenic at the
consumer level. We know that Arsenic is present in municipal drinking
water above safe levels and we are attempting to find out to what
extent Arsenic is posioning Americans.
Subject: Re: Freshwater that contains Arsenic
Answered By: pafalafa-ga on 07 Jun 2005 20:07 PDT

Thanks for adding the clarification to your question.

EPA recently (in 2001) lowered the drinking water standard for arsenic
from 50 parts per bilion to 10 parts per billion, and the new standard
is gradually going into effect.  EPA estimates that drinking water
supplies for 13 million Americans will be improved by the new standard
-- that is, 13 million Americans have been drinking water that
contains arsenic in excess of the new standard of 10 ppbs.

In particular, there are about 3,000 community water systems serving
11 million people that have levels above 10 ppbs, and another group of
about 1,100 water systems serving 2 million people that also have to
come into compliance.

NOTE that since the rule was promulgated in 2001, some -- or even many
-- of these water systems may have already come into compliance with
the new limits.

A fact sheet on the EPA rule can be found here:
Fact Sheet: Drinking Water Standard for Arsenic 
January 2001

and the most relevant excerpts are these:

--The Environmental Protection Agency (EPA) is finalizing a regulation
to reduce the public health risks from arsenic in drinking water. The
Agency is revising the current drinking water standard for arsenic
from 50 parts per billion (ppb) to 10 ppb. This revision will provide
additional protection for 13 million Americans against cancer and
other health problems, including cardiovascular disease and diabetes,
as well as neurological effects.

--Studies have linked long-term exposure to arsenic in drinking water
to cancer of the bladder, lungs, skin, kidney, nasal passages, liver,
and prostate. Non-cancer effects of ingesting arsenic include
cardiovascular, pulmonary, immunological, neurological, and endocrine
(e.g., diabetes) effects.

--EPA is setting the new arsenic standard for drinking water at 10 ppb
to protect consumers against the effects of long-term, chronic
exposure to arsenic in drinking water. EPA is using its discretionary
authority under the 1996 Amendments to the Safe Drinking Water Act to
set the standard at a level that "maximizes health risk reduction
benefits at a cost that is justified by the benefits."

--The new standard will apply to all 54,000 community water systems. A
community water system is a system that serves 15 locations or 25
residents year-round, including most cities and towns, apartments, and
mobile home parks with their own water supplies. EPA estimates that
roughly five percent, or 3,000, of community water systems, serving 11
million people, will have to take corrective action to lower the
current levels of arsenic in their drinking water.

--The new standard will also apply to 20,000 water systems that serve
at least 25 of the same people more than six months of the year, such
as schools, churches, nursing homes, and factories. EPA estimates that
five percent, or 1,100, of these water systems, serving approximately
2 million people, will need to take measures to meet the new arsenic
standard. Of all of the affected systems, 97 percent are small systems
that serve fewer than 10,000 people each.

--Arsenic occurs naturally in rocks and soil, water, air, and plants
and animals. It can be further released into the environment through
natural activities such as volcanic action, erosion of rocks, and
forest fires, or through human actions. Approximately 90 percent of
industrial arsenic in the U.S. is currently used as a wood
preservative, but arsenic is also used in paints, dyes, metals, drugs,
soaps, and semi-conductors. Agricultural applications, mining, and
smelting also contribute to arsenic releases in the environment.

--Higher levels of arsenic tend to be found more in ground water
sources than in surface water sources (i.e., lakes and rivers) of
drinking water. Compared to the rest of the United States, western
states have more systems with arsenic levels greater than 10 ppb.
Parts of the Midwest and New England have some systems whose current
arsenic levels are greater than 10 ppb, but more systems with arsenic
levels that range from 2-10 ppb. While many systems may not have
detected arsenic in their drinking water above 10 ppb, there may be
geographic "hot spots" with systems that may have higher levels of
arsenic than the predicted occurrence for that area.

I trust this information fully answers your question.  

However, please don't rate this answer until you have everything you
need.  If you would like any additional information, just post a
Request for Clarification to let me know how I can assist you further,
and I'm at your service.

All the best,


search strategy -- searched the EPA drinking water site for [ arsenic ]
Subject: Re: Freshwater that contains Arsenic
From: lauridsd-ga on 07 Jun 2005 12:43 PDT
Searching for "arsenic in groundwater", I found the following link:

Your question is a bit difficult to answer based on the fact that it
is probably necessary to include some other criteria.  For example,
the following question is a bit more specific and is more likely to be

"Of all of the groundwater samples tested across the country, what
percentage,  contain measureable concentrations of arsenic?"

According to the USGS, as of a November 2001 citation
(, the answer
to that question is 25%.

Remember, that statistics can be deceiving, however, and that many
more questions may need to be asked to get at the heart of the matter.
 While 25% of the 31,350 samples seems like quite a few (and perhaps
it is,) that statistic alone does not accurately convey the relative
danger or safety of the water in any given area.  Other probing
questions may need to be asked.  For example:

How much arsenic in water is considered dangerous?  (The US EPA and
the WOrld Health Organization say that 10ug/L (micrograms per liter)
is the maximum. )

How many of those 31,350 samples were at or above the 10ug/L limit?

Where were samples containing the highest concentrations of arsenic
collected? (See the map for that answer)

Where does the arsenic present in a given sample actually come from?

How was the data for this map collected?

Et cetera, et cetera, et cetera...

Hope this helps,


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