Researchers at Purdue University have...
on Private Wells Throughout the U.S. Place Homeowners at a Higher Risk
Would you be surprised if your customers had arsenic levels over 50 parts per billion (ppb) or five times the new maximum contaminant level (MCL)? How about 100 ppb? Or even 200 ppb! Some groundwater wells in the United States have reported values well over 300 ppb with a high arsenic level of 2,000 ppb reported in a few cases. In Maine, of 46 sites that reported arsenic levels over 10 ppb, 14 (30 percent) had levels above 100 ppb. The results from New Hampshire were not much different. Of the 29 sites reporting data, 11 (37 percent) had levels above 100 ppb. These levels of arsenic are alarmingly high, and many of these homeowners were unaware that arsenic was present in their wells and only became aware because they were either selling or buying a home.
The EPA has been the driving force behind reducing the acceptable arsenic levels in drinking water from 50 ppb down to 10 ppb on public water systems (PWS). The new standard goes into effect in January 2006. A tremendous amount of effort has gone into education, training and awareness to communities affected by this change, but private well owners are largely on their own to gather information since they are not regulated in the same manner. The map above highlights the arsenic levels around the United States reported by the EPA in 2002 based on samples taken from public water systems.1 A closer look reveals that arsenic levels from public water systems are not nearly as high as reported by some private well owners. Of the more than 1,300 PWS identified by the EPA in its 25-state analysis with arsenic levels above 10 ppb, approximately 62 PWS (5 percent) have arsenic levels above 50 ppb and of that only 12 PWS were above 100 ppb (less than 1 percent).1 By comparison, focusing just on New Hampshire, approximately 150 wells that service PWS have arsenic levels greater than 10 ppb and 10 percent above 50 ppb.2 Seventy-three percent of private wells in New Hampshire that require arsenic removal systems exceed 50 ppb of arsenic! The results by the number of public vs. private wells by arsenic level are summarized in Figures 1 and 2.
According to Bernie Lucey, from the New Hampshire Department of Environmental Services, “In New Hampshire, approximately 15 percent of PWS wells have arsenic levels above 10 ppb. However, it is not atypical to see arsenic levels on private wells higher than on PWS, but it is surprising that we do not see some PWS with levels as high as reported on private wells. In one particular area in New Hampshire, arsenic levels on a residential well recorded close to 2,000 ppb with neighboring houses seeing levels between 600 and 900 ppb. Generally, high arsenic levels such as these seem to be very isolated.”
It is common to see some variation in arsenic levels even within short distances and/or at different well depths. For instance, in Ohio, it is thought that a pre-Ice Age riverbed now holds the remains of glacial deposits that contribute to arsenic levels ranging up to 500 ppb in some private wells, but neighboring homes may have arsenic levels less than 100 ppb.3 Data from United States Geological Survey (USGS) in Southwestern Ohio shows that in a sampling of PWS wells, 55 ppb was the highest level of arsenic found.4 Mary Ann Thomas of the USGS indicated that in Ohio, arsenic is sorbed onto iron oxide but it is deeply buried in a reducing environment, and the lack of oxygen causes the arsenic to be desorbed into the aquifer. This is quite different from what has been reported in Wisconsin and Illinois where the presence of oxygen in the aquifer causes the arsenic to leach out of the bedrock.4
David Braley from Maine’s Bureau of Health concurs that arsenic levels on private wells are known to be higher in Maine and it is not understood why that is the case; however, he points out to homeowners, “don’t be too concerned with the source but instead solve the problem and eliminate the health risk by removing the arsenic.”
The health effects of arsenic are widely reported. According to a 1999 study by the National Academy of Sciences, arsenic in drinking water causes bladder, lung and skin cancer and may cause kidney and liver cancer. The study also found that arsenic harms the central and peripheral nervous systems, as well as heart and blood vessels, and causes serious skin problems. It also may cause birth defects and reproductive problems.5 Table 1 shows the cancer risk factors of exposure to arsenic according to the National Academy of Sciences.
It should be pointed out the EPA typically sets risk factors on a one in 10,000 risk. At arsenic levels of 300 ppb, the risk factor would be 1 in 17—drastically higher than the normal risk factor.
Because of this concern and elevated risk, various state and county health departments around the United States are starting to get proactive on raising the awareness of arsenic in private wells. New Jersey, for instance, has enacted a law in many counties within the state where arsenic is present that requires property owners have their wells tested for arsenic before any real estate transaction. Oakland County, Mich., has adopted a similar position. New Jersey has adopted a more stringent MCL of 5 ppb of arsenic. California is currently reevaluating the MCL and may become the second state to lower the MCL below the 10 ppb level.
According to a study conducted by the USGS in New England, “Elevated arsenic concentrations in private wells were much more prevalent than in public wells, in some cases by two to four times” says Joseph D. Ayotte, chief investigator for the study and a hydrologist with the USGS unit in Pembroke, N.H. “This may have important implications for the general public because more than 20 percent of the region’s population uses private wells for their water supply—much higher in some areas.”6
Arsenic generally occurs naturally in most water sources and is odorless, colorless and tasteless. To a lesser extent, some man-made sources of arsenic can occur from wood treatment, pesticide, pharmaceutical and miscellaneous industrial facilities. Many different types of food are additional sources of arsenic.
So, what are private well owners to do? The emergence of companies offering arsenic removal technologies has grown substantially over the last few years. Homeowners, well drillers, water dealers, etc., are faced with several treatment options to consider, resulting in a great deal of confusion. Many treatment options are ineffective or require pretreatment steps in order to perform acceptably. The following are several of the technologies well known to water professionals but ineffective at removing arsenic.
Table 2 (see page 12) lists some of the residential technologies known to remove arsenic.7 Several adsorptive media have been developed over the last few years and their capacities to remove arsenic can differ greatly. Regardless of the technology approach, many questions need to be asked and answered before a supplier can comfortably respond back to a homeowner if the technology is suitable. One technology that has quickly earned a proven record of accomplishment amongst water dealers has been granular ferric oxide (GFO). GFO, also known as Bayoxide E-33 (or sometimes AD33) is an NSF 61 listed media, which has successfully removed arsenic on many of the reported sites referenced in this article, including many of the sites listed above 100 ppb.
Companies involved with well drilling, have noticed the increase in arsenic awareness from its customers and real estate transactions. According to Gerard McKeown, director of sales for Amtrol Inc., “Our core customer base, the well drillers, have been reluctant to engage their customers in providing a solution because of the lack of proven technologies, but as technologies have performed reliably and provide a cost-effective approach, we are now able to assist our clients and keep real estate transactions moving forward.”
Many homeowners when deciding between a whole-house treatment system or a point-of-use product have been choosing the whole-house option. The primary reason is the cost of a GFO system is roughly the cost of buying one bottled water a day and all the water in the home is treated.10 Many homeowners want to feel more secure when showering, bathing or brushing teeth and consider a whole-house treatment system a better option for removing arsenic in their homes. Very few studies exist on the health effects of arsenic via skin adsorption and states have a differing opinion on what level is safe. Many experts believe the problem may not be a cause for any alarm but there is not a sufficient amount of data to draw any conclusions.
Another strong benefit of this technology has been the ability to remove both arsenic III as well as arsenic V. Arsenic III is more carcinogenic than arsenic V and many technologies require oxidizing the arsenic III to arsenic V by a separate treatment step. This reason along with its simplicity and high adsorptive capacity to remove arsenic as well as the fact that it does not require regeneration and thus can be disposed as a non-hazardous material are the reasons why New Jersey considers it the Preferred Treatment Choice for removing arsenic. The New Jersey health department has further stated that when considering POU or whole-house, they prefer homeowners carefully consider a whole-house system.8
Private well owners in known arsenic areas should be encouraged to have their wells tested on an annual basis. Using inexpensive simple test kits as a screening mechanism to determine if arsenic is present is one option, but certified water testing labs are the best choice for accurate results. Since most labs are not capable of speciating between the different forms of arsenic (As III or As V), make sure to choose a suitable technology that can remove both forms of arsenic.
One of the biggest challenges for solution providers is that homeowners believe they do not have harmful levels of arsenic in their water. According to Steve Spayd, project manager for Arsenic Well Treatment Research at New Jersey Department of Environmental Protection, “During the first six months of the New Jersey private well testing program, 1,928 wells have been tested and 72 (3.7 percent) had arsenic levels above 10 ppb. In other words, 72 families have benefited by knowing that their wells have unsafe arsenic levels.”9 Arsenic levels can vary quite widely even over short periods within a year. In addition, many sites indicate an increase in arsenic levels over time, which some individuals attribute to a lowering of the water table enabling arsenic to leach from the bedrock. Spayd further points out that “well depths can be a reason why varying arsenic levels can be seen. Homeowners on private wells who live on the same street are likely to have well depth differences which can result in noticeable differences in arsenic levels.”
Table 3 highlights data compiled from homeowners seeking some form of treatment in several states that show the number of samples reported and the maximum arsenic level identified. It is quite possible the data does not follow a normal bell shape curve primarily because people with high arsenic levels are more motivated to seek treatment.
It is foreseeable that other states could adopt a similar policy to that of New Jersey and require testing wells for arsenic prior to a real estate transaction. Furthermore, local authorities should make more effort to increase arsenic awareness to existing homeowners
who live in areas known to be high in arsenic. However, even when very high levels of arsenic are found, using a GFO system provides a homeowner with a proven cost-effective treatment to remove arsenic.
For a complete list of references, go to our website: www.wqpmag.com.