Arsenic Rule Could Cost Utilities Billions

The Environmental Protection Agency is seeking comment on a proposed arsenic rule that could cost water utilities $1.4 billion a year in operation expenses and $14 billion in capital costs, according water industry groups.

The proposed rule, published in June, calls for a standard of 5 parts per billion (ppb) for arsenic in drinking water. However, EPA is seeking comment on 3, 10 and 20 ppb as well. The American Water Works Association (AWWA) and other industry groups have encouraged EPA to set the new standard at no less than 10 ppb. At least one environmental group has called for the lower 3 ppb standard, however.

The current arsenic standard of 50 ppb in drinking water was set by EPA in 1975, based on a Public Health Service standard originally set in 1942. In March 1999, the National Academy of Sciences (NAS) completed a review of updated scientific data on arsenic and recommended that EPA lower the standard as soon as possible. Although the NAS did not recommend a specific numeric level, its recommendation formed the basis for EPA's proposal.

All 54,000 U.S. community water systems, serving 254 million people, would be subject to the new standard. However, EPA estimated that 6,600 utilities, which represent about 12 percent of all water suppliers in the nation and serve some 22 million people, would have to take corrective action. The vast majority of those systems serve 10,000 homes or fewer.

In general, drinking water supplies are contaminated by arsenic through natural processes such as erosion of rocks and minerals. Arsenic also can contaminate drinking water when used for industrial purposes. Arsenic is found at higher levels in ground water sources. Water systems in western states and parts of the Midwest and New England that depend on ground water will be most affected by the new rule.

According to the U.S. Geological Survey, 1 percent of water utilities have arsenic levels above the existing federal standard of 50 parts per billion (ppb), 8 percent exceed 10 ppb and 14 percent exceed 5 ppb.

For those systems that need to take corrective action, EPA estimates annual household costs to average $28 for Americans served by large systems and $85 for those served by systems serving fewer than 10,000 people. Over 98 percent of the cost to water systems comes from adding treatment equipment, chemicals, and oversight of the new treatment.

In its review of the current arsenic standard, the National Research Council recommended that additional research on the health effects of arsenic at low levels be done prior to a new standard being established. Although that research is not yet complete, the NRC's comments make it clear that the costs incurred by lowering the arsenic standard below 10 ppb must be closely evaluated in relation to the possible health benefits before the standard is implemented.

Some members of the NRC panel expressed concern that reducing the federal standard below 10 ppb would be unsupportable.

The costs of dropping the standard below 10 ppb are exorbitant. According to a recent American Water Works Association Research Foundation study, a 10 ppb standard would cost drinking water suppliers $600 million a year with capital costs of $5 billion. At 5 ppb, the standard would cost $1.4 billion a year with a capital cost of $14 billion, and a standard of 3 ppb would cost $2.8 billion a year with a capital cost of $28 billion.

The EPA estimates the 5 ppb rule would cost only about $374 million a year.

The agency's economic studies conducted over the past few years found that the standard of 10 parts per billion would cost half as much as its proposal, and that the standard of 3 parts per billion would cost twice as much as its proposal.

For each notch that the regulatory vise is tightened, there would be a corresponding reduction in cancers, the agency's scientists found. But the improvements would be relatively slight. And because most of the cancers at each level of control would be curable, the agency deemed that the health gains were worth only so much money spent cleaning up water supplies.

Large water systems would probably treat their water with relatively efficient technologies like filtering and adding lime. But systems that serve fewer than 10,000 people would probably choose less efficient methods, and the costs of treatment per household would probably be higher there. Large systems would be given three years to comply, and small systems five years.

"The subject of arsenic has been debated at the EPA for the better part of a decade or more," said Charles J. Fox, the agency's assistant administrator for water programs. "We think this (5 ppb proposal) is affordable, and it is important for public health protection. But some communities will see increases in drinking water rates to pay for this additional health protection."

The burden would fall most heavily in the Southwest, where many communities have tap water with high levels of arsenic. For example, the Albuquerque water system, which serves more than 400,000 people, has an arsenic level of 14 parts per billion, and the Norman, Okla., water system, which serves 80,000 people, has arsenic levels at about 36 parts per billion, according to federal data complied by the Natural Resources Defense Council.

In some communities, people may face a risk as high as 1 in 100 of developing cancer from contaminated water, according to a study published last year by the National Research Council. Erik Olson, a senior lawyer for the council, warned that the EPA proposal would still allow a cancer risk in the range of 1 in 10,000, a claim that the agency confirmed.

"Although it (the proposed rule) is a very significant step forward," Olson said, "it would still provide a higher cancer risk than any other EPA rule for tap water. I think that is a pretty serious precedent for the agency to be undertaking."

His environmental advocacy group has urged the agency to adopt a standard of 3 parts per billion, the strictest standard that is considered feasible with existing technology.

The AWWA has called for a standard of 10 parts per billion -- twice what the EPA is proposing and equal to the recommendation of the World Health Organization, according to Doug Marsano, an association spokesman. That standard would bring reductions in the vast majority of cities where arsenic is a problem, he said.

Long term exposure to low concentrations of arsenic in drinking water can lead to skin, bladder, lung, and prostate cancer. Non-cancer effects of ingesting arsenic at low levels include cardiovascular disease, diabetes, and anemia, as well as reproductive and developmental, immunological, and neurological effects. Short-term exposure to high doses of arsenic can cause other adverse health effects, but such exposures do not occur from U.S. public water supplies at the current standard of 50 ppb.

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 used as a wood preservative, but arsenic is also used in paints, dyes, metals, drugs, soaps, and semi-conductors. Burning fossil fuels, paper production, cement manufacturing, and mining can also release arsenic into the environment.

While many systems may not have detected arsenic in their drinking water above 5 ppb, there may be "hot spots" with systems higher than the predicted occurrence for an area. More water systems in western states that depend on underground sources of drinking water have naturally-occurring levels of arsenic at levels greater than 10 ppb than in other parts of the U.S. Parts of the Midwest and New England have some systems whose current arsenic levels range from 2-10 ppb.

More Information

The proposed arsenic rule is open for comment through the end of August. For general information on arsenic in drinking water, contact the Safe Drinking Water Hotline, at (800) 426-4791, or visit the EPA Safewater website at http://www.epa.gov/safewater or the arsenic website at http://www.epa.gov/safewater/arsenic.html.

EPA Details Arsenic Removal Technologies

A number of treatment technologies are available on the market to remove arsenic from drinking water. Most of them are effective only when treating arsenate, or As(V), which is most common in surface waters. Arsenite, or As(III) commonly is found in groundwater and is more difficult to treat. Fortunately, it can be oxidized to As(V) with oxidants such as chlorine, ferric chloride, and potassium permanganate.

In the early 1990s EPA supported pilot-scale studies examining technologies to remove arsenic from drinking water down to 1µ/L, or 1 ppb. The following is a summary of the technologies. In all cases, references to arsenic removal refers to arsenate:

Coagulation/Filtration (C/F), is an effective treatment process for removal of arsenic according to laboratory and pilot-plant tests. The type of coagulant and dosage used affects the efficiency of the process. Within either high or low pH ranges, the efficiency of C/F is reduced significantly. In testing, ferric sulfate out-performed alum and other coagulants. Disposal of the arsenic-contaminated coagulation sludge may be a concern especially if nearby landfills are unwilling to accept such a sludge.
Lime Softening (LS) operated within the optimum pH range of greater than 10.5 is likely to provide a high percentage of As removal for influent concentrations of 50 µ/L (50 ppb). However, it may be difficult to reduce consistently to 1 µ/L by LS alone. Systems using LS may require secondary treatment to meet that goal.
Activated Alumina (AA) is effective in treating water with high total dissolved solids (TDS). However, selenium, fluoride, chloride, and sulfate, if present at high levels, may compete for adsorption sites. AA is highly selective towards As(V); and this strong attraction results in regeneration problems, possibly resulting in 5 to 10 percent loss of adsorptive capacity for each run. Application of point-of-use treatment devices would need to consider regeneration and replacement.
Ion Exchange (IE) can effectively remove arsenic. However, sulfate, TDS, selenium, fluoride, and nitrate compete with arsenic and can affect run length. Passage through a series of columns could improve removal and decrease regeneration frequency. Suspended solids and precipitated iron can cause clogging of the IE bed. Systems containing high levels of these constituents may require pretreatment.
Reverse Osmosis (RO) provides removal efficiencies of greater than 95 percent when operating pressure is at ideal psi. However, water rejection may be an issue. If RO is used by small systems in the western U.S., 60 percent water recovery could lead to an increased need for raw water. Discharge of reject water or brine may also be a concern. Where scarcity is an issue, water recovery will need to be optimized, which could lead to increased costs for arsenic removal.
Electrodialysis Reversal (EDR) is expected to achieve removal efficiencies of 80 percent. One study demonstrated arsenic removal to 3 µ/L from an influent concentration of 21 µ/L.
Nanofiltration (NF) was capable of arsenic removals of over 90 percent. The recoveries ranged between 15 to 20 percent. A recent study showed that the removal efficiency dropped significantly during pilot-scale tests where the process was operated at more realistic recoveries. If nanofiltration is used by small systems in the western U. S., water recovery will likely need to be optimized due to the scarcity of water resources. The increased water recovery can lead to increased costs for arsenic removal.

Ion Exchange with Brine Recycle. Research recently completed by the University of Houston (Clifford) at McFarland, CA, and Albuquerque, NM, has shown that ion exchange treatment can reduce arsenic (V) levels to below 2 µ/L even with sulfate levels as high as 200 mg/L. Sulfate does impact run length, however; the higher the sulfate concentration, the shorter the run length to arsenic breakthrough. The research also showed the brine regeneration solution could be reused as many as 20 times with no impact on arsenic removal provided that some salt was added to the solution to provide adequate chloride levels for regeneration. Brine recycle reduces the amount of waste for disposal and the cost of operation.
Iron (Addition) Coagulation with Direct Filtration. The University of Houston (Clifford) recently completed pilot studies at Albuquerque, NM, on iron addition (coagulation) followed by direct filtration (microfiltration system) resulting in arsenic being consistently removed to below 2 µ/L. Critical operating parameters are iron dose, mixing energy, detention time, and pH.
Conventional Iron/Manganese (Fe/Mn) Removal Processes. Iron coagulation/filtration and iron addition with direct filtration methods are effective for arsenic removal. Source waters containing naturally occurring iron and/or manganese and arsenic can be treated for arsenic removal by using conventional Fe/Mn removal processes. These processes can significantly reduce the arsenic by removing the iron and manganese from the source water based upon the same mechanisms that occur with the iron addition methods. The addition of iron may be required if the concentration of naturally occurring iron/manganese is not sufficient to achieved the required arsenic removal level.