Chlorine Pollutants High in DC Tap Water

Tests Find Hazardous Chlorination Byproducts

Thursday, July 19, 2007

Chlorine Pollutants High in DC Tap Water

Tests Find Hazardous Chlorination Byproducts

In spite of the best efforts of the Washington Aqueduct to provide quality drinking water to the District of Columbia, tap water tests from May, 2007 revealed toxic by-products of the chemicals used to purify Potomac River water, at levels above annual federal health limits. These results illustrate the tremendous difficulties that water utilities face when trying to provide tap water that is free of potentially deadly bacteria and pathogens, yet not contaminated with toxic by-products of the chemicals used to kill these same microbes. This problem is particularly acute when utilities draw water from poorly protected water sources like the Potomac River. As recently reported in the Washington Post, the Potomac may not even be suitable for swimming; turning this water into safe drinking water is a serious public health challenge.

Based on these test results the Environmental Working Group (EWG) is recommending carbon filtration for all 1.1 million consumers of tap water from the Washington Aqueduct in Washington DC and northern Virginia. Carbon filtration of tap water will dramatically lower levels of toxic disinfection byproducts; it is also 10 to 20 times less expensive than bottled water, and does not produce the waste and pollution associated with the packaging and transport of bottled water.

Filtering water at home is cheaper than buying bottled water

Source: EPA. 2004. Estimated Per Capita Water Ingestion and Body Weight in the United States–An Update. October, 2004. EPA-822-R-00-001
American Water Works Association. 2007. Questions and answers about your water. http://www.drinktap.org

 

EWG collected tap water samples in May, 2007, from 18 locations across Washington D.C., including the U.S. Capitol, EPA headquarters, parks, schools, and residences of pregnant women and other groups susceptible to health harms from exposures to disinfection byproducts. We commissioned tests from an accredited lab for two classes of disinfection byproducts — trihalomethanes, or THMs, and haloacetic acids, or HAAs. The laboratory analyses found:

 

  • More than 40 percent of the tap water samples contained chemical byproducts of water treatment above annual federal health limits. The group of contaminants known as haloacetic acids (HAAs) were found at their highest levels since 2001, the last year before the Washington Aqueduct modified its treatment techniques in an attempt to reduce levels of trihalomethanes, related byproducts of tap water chlorination.

  • HAAs were highest at the Martin Luther King Jr. Memorial Library, an elementary school in the district's Northwest quadrant, and the home of a woman who was 9 months pregnant.

  • Almost 90 percent of the samples had THMs at levels associated in epidemiological studies with low birth weight and serious birth defects in infants. TTHM levels were highest at the National Mall, the same elementary school, and the home of a 2-year-old infant.

Benefits of water disinfection come at a price. Chlorination of tap water is one of the greatest public health improvements of the last 100 years, vastly reducing deaths from water-borne diseases. But chlorination produces disinfection byproducts (DBPs) like THMs and HAAs that are themselves potentially harmful.

Because of the recognized health risks of the byproducts, in particular THMs, many utilities, including the Washington Aqueduct, have switched from treatment using so-called free chlorine to compounds called chloramines, which tend to produce lower levels of the handful of disinfection byproducts for which EPA has set legal limits, including THMs and HAAs. But because chloramines are not as effective at disinfection as free chlorine, the Aqueduct, like other utilities that use chloramine, periodically switches back to chlorine. This so-called "chlorine burn" removes sludge and sediment from the pipes, but also temporarily raises the level of disinfection byproducts. This year the utility's chlorine burn was conducted between April 7 and May 7.

While chloramines appear to help lower THM levels, they also produce an entirely different set of byproducts, including the HAAs and other byproducts, for which we have less information about long-term human health effects. A recent EPA study found that water treated with chloramines had the highest levels of iodacetic acid, a byproduct that in animal studies has been found toxic to cells and DNA. In general, however, the long term public health consequences of exposure to chloramines and chloramine byproducts is poorly understood.

What is known about HAAs, however, raises concerns. EPA classifies HAAs as possible human carcinogens, and peer-reviewed studies have identified adverse reproductive and developmental effects, and the ability to damage DNA. The state of Oregon has warned that long term exposure to HAAs at levels equal to those found in DC tap water could cause injury to the brain, nervous system, the eyes, and the reproductive system.

Disinfection byproducts are a bigger problem than these tests show. EPA scientists have identified a total of 600 disinfection byproducts in tap water but EPA has set legal limits in tap water for only 11. And these legal limits, such as those for HAAs and THMs, are established as a balance between health, treatment cost and feasibility.

This is a critical point for most consumers: The legal limit, or MCL, is not intended to be a true safe exposure level. For almost all contaminants in tap water, including those identified in this analysis, the MCL allows far more contamination than the truly safe level, or what EPA refers to as the public health goal.

In 1999, EPA strengthened the legal limit for THMs in tap water and set a first-time standard for HAAs due to these chemicals' potential links to cancer, birth defects, and other adverse health outcomes. To comply with these tighter standards, DC Water and Sewer Authority began using chloramine as a disinfectant because of its known capacity to lower levels of the regulated byproducts. This switch, which the utilities' water quality test reports show did indeed lower THM and HAA levels, also spurred some significant negative consequences: it likely created a complex, new suite of disinfection byproducts that are neither defined nor studied; and it contributed to elevated lead levels in tap water across the District, a problem that prompted additional manipulations in water chemistry by the utility that are still under study.

Protecting tap water at the source. If the Potomac River were less polluted as it flowed into the utility's intake pipe, less chlorine and chloramines would be needed, and levels of disinfection byproducts would be lower as a result. But government policies, in general, do little to advance this goal. Instead, taxpayers pour billions of dollars into federal programs like farm subsidy payments that actually exacerbate pollution problems, and then pile on additional billions for water treatment facilities that try to clean it up. Very little is spent on more effective and efficient measures to protect rivers and streams from pollution in the first place.

Agriculture is the top source of pollution in the Potomac River watershed, but efforts to control agricultural pollution remain largely unfunded. From 1999 through 2005, taxpayers spent five times more money subsidizing farmers in the Potomac River basin as they did on programs to control agricultural pollution - $287 million on subsidies compared to $57 million on conservation and pollution control. Many farmers received no money at all. In an era of tight federal budgets, political pressure to fully fund farmer subsidies almost always trumps whatever concerns might exist about controlling agricultural pollution. In 2004 and 2005, 4,155 farmers in the Potomac watershed were denied funding for conservation and water quality projects due to lack of available funds.

Recommendations. The findings presented here make a strong case for keeping sources of tap water clean before they require expensive and potentially harmful treatment with chlorine or chloramines. But until such measures are in place and contaminant levels are dramatically reduced from current levels, EWG recommends that anyone drinking DC tap water use some form of carbon filtration designed to reduce levels of THM and HAAs. In addition:

  • Farm polices must be reformed to fully fund programs specifically designed to keep agricultural pollutants of all kinds – manure, fertilizer, pesticides and soil – out of tap water supplies.
  • Safety standards for chlorination and chloramine byproducts must be reevaluated in light of research indicating that current regulations are not stringent enough.

  • Greater efforts are put in place to educate the public about the health risks of chlorine and chloramine byproducts and to warn all Aqueduct water consumers of the annual chlorine burn.

 

Pollution + Disinfectants = Problems

There is no question that the wide scale use of chemical disinfectants in public drinking water supplies has been one of the greatest public health advances in the twentieth century. Over time, however, we have become overly reliant on chemical treament of tap water as we have simultaneously failed to protect and clean up the sources of this water. This has placed water purveyors like the Washington Aqueduct in an intractable bind where the process of purification of polluted source water exposes consumers to unnecessarily high and potentially unsafe levels of toxic chemicals formed during the treatment process.

Chlorine is very effective at killing and inactivating disease-causing microganisms in tap water. The problem is that if the water also contains "natural organic matter" the chlorine will react with the humic and fulvic acids that form as the organic matter breaks down. These reactions, in turn, produce numerous other chemical compounds that are collectively called disinfection byproducts (DBPs).

Although scientists have identified 600 different kinds of DBPs, the Environmental Protection Agency (EPA) currently only regulates just eleven (Richardson 1998, 1999a, 1999b, 2003). These regulated compounds include four trihalomethanes (chloroform, bromodichloromethane, bromoform, and dibromochloromethane), and five haloacetic acids (monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid), which together are linked to a variety of adverse health effects such as cancer (DeAngelo 1997; Villanueva 2007), birth defects (Klotz, 1999; Porter 2005), and an increased incidence of miscarriage (Waller 1998).

After the EPA tightened its health standards for the trihalomethanes (THMs) and implemented health standards for the haloacetic acids (HAAs) in 1999, several utilities decided to alter their disinfection practices by switching to a new disinfectant called chloramine, which is made from chlorine and ammonia gases. Washington Aqueduct, the utility responsible for the treatment of drinking water in the District of Columbia, and Arlington County and Falls Church in Northern Virginia, made the switch to chloramines in November of 2000 (EPA 2006).

There are several reasons why utilities find chloramines appealing: they are more stable than chlorine and reduce the peak levels of at least some toxic chlorination byproducts – particularly THMs. The EPA has reported, for example, that the Washington Aqueduct's switch to chloramines resulted in an estimated average reduction in monitored DBPs of 47% (EPA 2006).

But chloramines also have significant drawbacks. They are not only toxic to kidney dialysis patients, who cannot drink chloraminated water, they are also extremely toxic to fish, which die if chloraminated water is used in their tanks. And chloramines also produce a whole new complex of contaminants that are very poorly studied.

To make matters even more complicated, many utilities that use chloramines decide to temporarily switch back to free chlorine in order to "dislodge biofilms and sediment in water mains" (EPA 2007). Since spring 2002, the Washington Aqueduct has used this practice on a more or less annual basis, implementing a month-long "chlorine flush" of its system roughly every year. This means that customers of chloramines-using utilities often end up being exposed to multiple different sets of DBPs over time, at varying levels.

It is tempting to chalk up all of the problems with DBPs to an unwanted but unavoidable consequence of the organic matter naturally found in the rivers, lakes, and reservoirs. But the underlying sources of this "natural organic matter" are not actually natural at all. In much of the country, the bulk of organics in drinking water supplies stems from agriculture in the form of uncontrolled soil erosion, manure and fertilizer runoff, and from municipal sewage treatment plant discharges:

  • About one billion tons of topsoil erode from U.S. cropland each year (USDA 2001), much of it deposited in streams and rivers. Soil contains organics that combine with chlorine to form disinfection byproducts. Soil in combination with manure eroding from pasture and range lands contains even higher amounts of DBP-forming organics.

  • Studies released by the US Geological Survey (USGS) found that fertilizer used in agriculture accounted for 17% of total phosphorus that entered major river basins in the U.S. (CSP, 2007). Excess phosphorus causes uncontrolled algae blooms that create massive slugs of organic matter, which then combine with chlorine to form chlorination byproducts. Most phosphorus is absorbed to soil particles in the field and is carried to streams and rivers through soil erosion. USGS studies show that three-quarters of all streams and rivers in the U.S. are polluted with phosphorus at levels that can support uncontrolled algae growth (USGS 1999, Cooke 1989).

  • In urban areas, sewage treatment plants flush large quantities of organics and phosphate into rivers that serve as drinking water supplies. Some of these organics can combine with chlorine to form chlorination byproducts. The phosphate stimulates algae growth that ultimately leads to chlorination byproducts. In national water quality surveys, USGS finds the highest phosphate levels in the country in urban areas impacted by sewage discharges (USGS 1999).

For the Potomac River watershed, agriculture is the top pollution source. Efforts to control farm runoff of soil, fertilizer and manure, however, remain largely unfunded. From 1999 through 2005, taxpayers spent five times more money subsidizing farmers in the Potomac River basin as they did on programs to control agricultural pollution - $287 million on subsidies compared to $57 million on conservation. In an era of tight federal budgets, political pressure to fully fund farmer subsidies almost always trumps whatever concerns there might be about controlling agricultural pollution. As a result, 4,155 farmers in the Potomac watershed were denied funding for conservation programs in 2004 and 2005 due to lack of available funds.

This has real-world consequences for DC residents. If the Potomac River were less polluted as it flowed into the utility's intake pipe, disinfectant loads could be reduced, and levels of disinfection byproducts would be lower as a result.

 

Findings

On March 27, 2007, the Washington Aqueduct and Army Corps of Engineers issued a news release advising the public of its annual chlorine burn from April 7 to May 7. During the burn, the utility adds higher levels of chlorine to the system in an attempt to remove residual films and bacteria from the inside of its delivery pipes. The news release warned home users of kidney dialysis machines and owners of aquatic pets, but failed to advise all 1.1 million customers of the Washington Aqueduct about their potential exposure to increased levels of disinfection byproducts.

In light of this exposure and concern over the potential health effects, the Environmental Working Group decided to test water from the District of Columbia for disinfection byproducts (DBPs), in particular total trihalomethanes (THMs) and haloacetic acids (HAAs). Tap water samples were taken from 19 locations in the District from May 1 to May 4, 2007. These locations were distributed throughout three of the four quadrants in the district (NW, NE and SE) and all eight wards (see Table 1).

The sample water was collected from drinking water sources, such as kitchen taps or water fountains, whenever possible, and sent to the Environmental Engineering and Technology, Inc. laboratories to be analyzed for HAAs and THMs. Unfortunately, the vials containing the THM sample taken from one of the sites (the library) broke in transit to the lab, leaving 18 sites from which we were able to assess THM levels.

 

Table 1: Results of May 2007 D.C. Tap Water testing

 

 

Location Sampled Quadrant Description
of sample
TTHM/ppb HAA/
ppb
Chloroform/
ppb
Elementary School NW Kitchen Tap 61.2 83.3 52.5
Residence with
pregnant women #1
NW Bathroom Tap 45.5 49.4 37.5
Residence with
pregnant women #2
  Kitchen Tap 50.8 74.9 42.5
Residence with infant NW Kitchen Tap 62.2 67.7 52.6
Residence with
immunocompromised person #1
NW Kitchen Tap 51.9 57.7 43.7
Residence with
immunocompromised person #2
NW Kitchen Tap 41.5 41.3 34.4
Residence with elderly person NW Kitchen Tap 53.5 69.0 44.8
Residence with woman of
reproductive age #1
SE Kitchen Tap 53.5 55.2 45.2
Residence with woman of
reproductive age #2
NW Kitchen Tap 52.7 57.7 43.0
Office catering to
immunocompromised persons
NW Kitchen Tap 50.4 58.8 42.4
Anacostia Park SE Water Fountain 46.7 66.7 39.6
Fort Dupont Park SE Bathroom Tap 55.5 71.7 47.0
MLK Jr. Library NW Bathroom Tap --- 89.4 ---
The National Zoo NW Bathroom Tap 41.3 63.0 34.7
EPA Headquarters NW Bathroom Tap 38.4 37.2 27.9
Federal Courthouse NW Water Fountain 42.6 59.4 35.5
The Capitol NE Bathroom Tap 30.7 24.1 26.8
The National Mall NW Water Fountain 72.8 46.6 63.3
Union Station NE Bathroom Tap 58.2 57.3 49.3

 

 

Many samples exceeded legal limit for HAAs

Due to the higher than normal chlorine levels added to tap water during the chlorine burn, EWG expected our tests to reveal higher than average levels of chlorination byproducts, particularly THMs. What we found was while THM levels were not significantly increased, many samples contained very high levels of HAAs: HAA levels were their highest since the switch to chloramination in 2001, and 42% of the samples had HAA concentrations higher than the EPA’s legal annual limit for these compounds, known as the maximum contaminant level (MCL). More than two-thirds of the samples were within 95% of the annual MCL. The sample with the highest HAA concentration, the Martin Luther King Jr. Memorial Library, surpassed the annual MCL by almost 50%, rising to a concentration of almost 90ppb.

Notably, the HAA levels in seven locations (37% of our samples) were higher than any of the maximum detected HAA concentrations reported by the water utility in the past 6 years (2001-2006), including samples from two public parks (Fort Dupont Park and Anacostia Park), an elementary school and the residences of pregnant women and infants. This finding is interesting as it implies that HAA levels during the chlorine burn return to those found before Washington Aquaduct switched to chloramines.

Chart showing Washington DC haloacetic acid levels

 

 

Source: D.C. tap water samples collected by EWG from May 1 to May 4 2007. Samples analyzed by Environmental Engineering and Technology, Inc. laboratories in Newport News, VA.

Notes: 1. Allowable limit in tap water, the Maximum Contaminant Level (MCL), is set at a level higher than some suspected health risks because EPA sets drinking water standards under the Safe Drinking Water Act by balancing health concerns against treatment costs and feasibility. The MCL is based on the annual average concentration. The unit ppb is parts per billion of HAAs in water or micrograms (µg) per liter.

 

Chart showing haloacetic acid levels in 7 of 18 locations are higher than any of the maxium levels reported by the water utility in the past 6 years (2001-2006)

 

 

Source: HAA test results from D.C. Water and Sewer Authority(DCWASA) are the maximum reported detections from Washington Aqueduct's annual water quality reports for customers(www.dcwasa.com/waterquality/waterquality_reports.cfm). EWG's May 2007 test results from samples collected by EWG from May 1 to May 4 2007 and analized by Environmental Engineering and Technology, Inc. of Newport News, VA

 

HAAs have been classified by the EPA as possibly carcinogenic to humans because of evidence of carcinogenicity in animals. According to the EPA, long-term consumption of water that has HAA concentrations in excess of the agency’s safety standard is associated with an increased risk of cancer (EPA 2002). A technical bulletin released by the Oregon Department of Human Services (2004) also warned that long-term exposure to HAAs at or above the MCL might cause injury to the brain, nerves, liver, kidneys, eyes and reproductive systems.

 

While there have been few epidemiological studies on the potential health effects of HAAs, there is evidence suggesting that HAA exposure during the second and third trimesters of pregnancy may be linked to intrauterine growth retardation and low birth weight (Hinckley 2005; Porter 2005). Two HAAs, dichloroacetic acid and trichloroacetic acid, have been shown to cause severe skin and eye irritations in humans (NTP 2005).

Additional studies point to concerns with specific HAAs. Dibromoacetic acid has been shown to disturb the balance of the intestinal tract, whereby increasing the risk of opportunistic bacteria colonizing this tract and cause disease, especially in immunocompromised hosts (Rusin 1997). This particular HAA compound has also been shown to be toxic to the sperm of adult rats at concentrations as low as 10 parts per billion, and to cause a range of neurological effects ranging from awkward gait to tremors and immovable hind limbs at high doses. (Linder 1995).

 

 

THM levels often higher than what studies show are safe

Although the THM concentrations in the samples were all below the EPA’s MCL, 89% were above the level (40 parts per billion) that epidemiological studies have associated with adverse health effects in infants, ranging from low birth weight to neurological abnormalities. The locations with the highest THM concentrations were the National Mall, the home of a 2-year-old infant and the elementary school. The Capitol and the headquarters of the EPA had the lowest concentrations of both HAAs and THMs.

Epidemiological studies have found increased incidences of neural tube defects, small body length, and small head size in women drinking water containing only 40 ppb THMs (Kanitz 1996; Klotz 1999), and a recent study finds an increased risk of bladder cancer associated with exposures as low as 50 ppb (Villanueva 2007). Researchers have also found links to low birth weight and first trimester miscarriage in pregnant women drinking water with just 60 ppb and 75 ppb, respectively (Bove 2002). These levels are all below the EPA’s current MCL of 80 ppb, suggesting that the federal limit is not low enough to be health protective.

Chart showing health effects at various THM concentrations

 

Source: D.C. tap water samples collected by EWG from May 1 to May 4 2007. Samples analyzed by Environmental Engineering and Technology, Inc. laboratories in Newport News, VA. Potential health risks noted on graph are from peer-reviewed scientific literature, with full references listed in graph footnotes.

Notes: 1. Bove FJ, Fulcomer MC, Klotz JB, Esmart J, Dufficy EM, Savrin JE. 1995. Public drinking water contamination and birth outcomes. Am J Epidemiol 141: 850-62.
2. Waller K, Swan SH, DeLorenze G, Hopkins B. 1998. Trihalomethanes in drinking water and spontaneous abortion. Epidemiology 9: 134-40.
3. Gallagher MD, Nuckols JR, Stallones L, Savitz DA. 1998. Exposure to trihalomethanes and adverse pregnancy outcomes. Epidemiology 9: 484-489.
4. Klotz JB, Pyrch LA. 1999 Neural tube defects and drinking water disinfection by-products. Epidemiology 10: 383-90.
5. Kanitz S, Franco Y, Patrone V, Caltabellotta M, Raffo E, Riggi C, et al. 1996. Association between drinking water disinfection and somatic parameters at birth. Environmental health perspectives 104: 516-20.
6. Villanueva C, Cantor K, Grimalt J, Malats N, Silverman D, Tardon A, et al. 2007. Bladder cancer and exposure to water disinfection by-products through ingestion, bathing, showering, and swimming in pools. American journal of epidemiology 165(2): 148-56.

 

In addition, while its findings remain controversial, one 1996 study found a relationship between women exposed to just 10 ppb of one particular THM (chloroform) and an increased risk of intrauterine growth retardation and babies born small for their gestational age (Reif 1996). This finding is notable because all of the samples in our study had chloroform levels exceeding this value, by as much as six times in some cases.

Other epidemiological studies have found that levels of THMs between 80 and 100 ppb and above are associated with increased incidences of neural tube, central nervous system, and major cardiac birth defects (Bove 1995; Klotz 1999), providing more evidence that the EPA’s MCL may only be marginally health protective. Researchers have also found associations with oral cleft defects (Bove 1995) and stillbirth (Dodds 1999) in women who were exposed to more than 100 ppb of THMs during pregnancy. And animal studies have found that at high doses individual THMs can cause decreased body weight, decreased heart, livers and kidney weights, and renal tube degeneration, among other effects (NTP 2007).

 

 

Unanswered Questions

This study highlights many of the unanswered questions surrounding tap water disinfection in the DC area. Ultimately, the most important questions involve the decision to alter disinfection practices at the Washington Aqueduct, switching from chlorine to chloramines. This is of primary importance due to the exposure of 1.1 million people to a number of compounds that have not been fully assessed for long-term health effects in humans. In a recent nationwide DBP study conducted by the EPA (2002) it was reported that chloraminated drinking water had the highest levels of iodinated DBPs and studies have found that iodoacetic acid, one of these iodinated DBPs, is a potent toxin to cells and cellular DNA in mammalian cells (Plewa 2004). Although switching to chloramination achieved the desired effect of reducing THM levels, the decision may have inadvertently exposed the population to additional unregulated byproducts that are more harmful in the long run.

The second issue that needs to be addressed is the necessity of the annual “chlorine burn” and the potential health effects of this continual cycling of disinfectants and the resulting mix of disinfection byproducts to which people are exposed. Since chlorination of tap water is known to produce DBPs associated with adverse health effects, the fact that this annual procedure has to be performed poses questions about the efficacy of chloramines for water disinfection and, more importantly, raises concerns about whether enough amount of research was conducted before this decision was imposed upon the public.

Third, evidence presented in several studies strongly suggests that the current EPA MCLs are not adequate to protect public health. These studies show occurrences of adverse health effects below the MCLs, especially in the case of THMs, where reproductive and developmental effects have been observed as a result of exposures as low as 40 ppb. The EPA must, therefore, revise their standards, using data based on current studies, so that their "safe dose" is in fact safe for all populations.

Finally, since the formation of DBPs result from a reaction between chlorine, whether from chlorination or chloramination, and organic matter in surface waters, cleaner source water is the critical step to reliably reduce these byproducts while at the same time guaranteeing water as free of pathogens as possible. By failing to clean up source water, the Congress, EPA, and polluters are leaving Americans with no choice but to consume high levels of DBPs.

For the majority of the water systems with elevated DBP levels, cleaner source water will require aggressive action to reduce agricultural pollution, runoff from suburban sprawl and upstream sewage discharges. The public and policy makers have been led to believe that they must accept either water polluted with pathogens or water contaminated with high levels of chlorination and chloramination byproducts. This is simply not true. Tap water in DC and, in fact, the entire United States, can meet pathogen standards and be low in DBPs as well.

 

Recommendations

Recommendations for consumers:

In 2006, researchers from Universite Laval in Quebec, Canada found that the use of activated-carbon filters is one of the most effective ways for households to reduce THM and HAA concentrations in drinking water (Lévesque, 2006). The study found this method to be more effective than the other methods commonly used to improve the taste, smell and appearance of drinking water - i.e., storing water in the refrigerator for 48 hours prior to consumption and boiling water before storage - and have the added benefit of reducing lead levels which is a particular concern for DC residents.

Carbon filtration systems come in various different forms, including pitchers, faucet-mounted attachments, as well as larger systems that are installed on or under counter tops. Prices vary and may be deceiving since different systems require filter replacement at different frequencies. EWG research shows that pitcher and faucet-mounted systems are typically the most economical, with yearly costs typically in the range of about $100. Counter-top and under-counter systems tend to be more expensive at the outset, though the yearly maintenance costs are often not that much higher than the pitcher and faucet-mounted systems. The prices for all of these systems pale in comparison to the amount that a family of four would spend if they were purchasing bottled water, which EWG estimates to range between $950 and $1,800 per year.

Before purchasing, it is important to do your research, for not water filters using activated carbon remove DBPs. Click here to see a list of some filters that reduce the levels of at least some DBPs. EWG also recommends that consumers examine a recent Consumer Reports study that actually tested more than a dozen of common carbon filters for their ability to remove the THM chloroform. CR found that while many scored “very good” or “excellent,” a number of others scored “fair” or “poor” (Consumer Reports 2007). Click here to find CR’s study. Whatever system you end up purchasing, remember to change the filter according to the manufacturer's guidelines, or it will become clogged and cease to function effectively.

Numerous studies have shown that showering and bathing are important routes of exposure for THMs and certain other DBPs, and may actually contribute more to total exposure than drinking water (OEHHA 2004, Xu and Weisel 2003, Weisel and Laskin ND). One study, for example, found the highest chloroform exposure values among adults taking a 30-minute bath daily (Krishnan 2003). For this reason, consumers should consider purchasing a whole-house filtration system if they want to protect themselves from DBP-related health effects to the fullest extent possible. Consumers should be aware, however, that many whole-house filtration systems don’t actually remove DBPs, and those that do typically cost several hundred dollars to install with yearly maintenance costs that can also run into the hundreds of dollars. This option may also not be worthwhile for those who are more concerned with HAAs than other DBPs, since preliminary research has suggested that showering and bathing are not actually important exposure routes for these compounds (Weisel and Laskin ND).

  • Use a carbon filter to reduce DBPs in your home’s drinking water
  • Consider purchasing a whole-house filtration system to further reduce DBP exposure

Policy recommendations:

Agriculture is the top source of pollution in the Potomac River watershed, but efforts to control agricultural pollution remain largely unfunded. From 1999 through 2005, taxpayers spent five times more money subsidizing farmers in the Potomac River basin as they did on programs to control agricultural pollution - $287 million on subsidies compared to $57 million on conservation and pollution control. In an era of tight federal budgets, political pressure to fully fund farmer subsidies almost always trumps whatever concerns might exist about controlling agricultural pollution. As a result, 4,155 farmers in the Potomac watershed were denied funding for conservation programs in 2004 and 2005 due to lack of available funds.

EWG’s findings argue strongly for keeping sources of tap water clean before they require expensive and potentially harmful treatment with chlorine or chloramines. But until such measures are in place and contaminant levels are dramatically reduced from current levels, EWG recommends that anyone drinking DC tap water use some form of carbon filtration designed to reduce levels of THM and HAAs.

In addition, we recommend that:

  • Farm polices must be reformed to fully fund programs specifically designed to keep agricultural pollutants of all kinds – manure, fertilizer, pesticides and soil – out of tap water supplies.

  • Safety standards for chlorination and chloramine byproducts must be reevaluated in light of research indicating that current regulations are not stringent enough.

  • Greater efforts are put in place to educate the public about the health risks of chlorine and chloramine byproducts and to warn all Aqueduct water consumers of the annual chlorine burn.

 

References: 

Bove FJ, Fulcomer MC, Klotz JB, Esmart J, Dufficy EM, Savrin JE. 1995. Public drinking water contamination and birth outcomes. American journal of epidemiology 141(9): 850-62.

Bove F, Shim Y, Zeitz P. 2002. Drinking water contaminants and adverse pregnancy outcomes: a review. Environmental health perspectives 110 Suppl 1: 61-74.

Consumer-Reports. 2007. Water filters: Simple, effective ooptions. Available: http://www.consumerreports.org [accessed 2007].

Cooke G, Carlson R. 1989. Reservoir Management for Water Quality and THM Precursor Control: AWWA Research Foundation and American Water Works Association.

CSP. 2007. Conservation Security Program (CSP) Program Assessment: A report from the Soil and Water Conservation Society and Environmental Defense: Conservation Security Program.

DeAngelo AB, Daniel FB, Most BM, Olson GR. 1997. Failure of monochloroacetic acid and trichloroacetic acid administered in the drinking water to produce liver cancer in male F344/N rats. Journal of toxicology and environmental health 52(5): 425-45.

Dodds L, King W, Woolcott C, Pole J. 1999. Trihalomethanes in public water supplies and adverse birth outcomes. Epidemiology 10: 233-37.

EPA. 2002. Microbial Health Effects Tables: Potential Adverse Health Effects from high/long-term exposure to hazardous chemicals in drinking water.

EPA. 2002. The Occurrence of Disinfection By-Products (DBPs) of Health Concern in Drinking Water: Results of a Nationwide DBP Occurrence Study.

EPA. 2006. Lead in DC Drinking Water: Changes in Lead Levels during Annual Switch to Free Chlorine.

EPA. 2006. National Primary Drinking Water Regulations: Stage 2 Disinfectants and Disinfection Byproducts Rule; Final Rule. (Agency EP, ed): Government Printing Office, 107.

EPA. 2007. Lead in Drinking Water: Corrosion Control.

Hinckley AF, Bachand AM, Reif JS. 2005. Late pregnancy exposures to disinfection by-products and growth-related birth outcomes. Environmental health perspectives 113(12): 1808-13.

Kanitz S, Franco Y, Patrone V, Caltabellotta M, Raffo E, Riggi C, et al. 1996. Association between drinking water disinfection and somatic parameters at birth. Environmental health perspectives 104: 516-20.

Klotz JB, Pyrch LA. 1999. Neural tube defects and drinking water disinfection by-products. Epidemiology 10(4): 383-90.

Krishnan K. 2003. Evaluation of the relative importance of dermal and inhalation routes for developing drinking water guidelines for trihalomethanes. 602-4500059013: Health Canada.

Levesque S, Rodriguez MJ, J S, C B, F P. 2006. Effects of indoor drinking water handling on trihalomethanes and haloacetic acids. Water research 40(15): 2921-30.

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