Where does the Lead in Wells Come From

In 2012, the Macon County Health Department in North Carolina discovered county-wide water lead contamination in private wells due, they reported, to corrosion of galvanized well components. In North Carolina current well construction code requires the installation of a tap on the well; thus, they were able to differentiate lead contamination originating from household plumbing and lead contamination originating from the well.

They found "first draw samples" collected at the wellhead between 2008 and 2012 documented that 55 of 398 (14%) of newly constructed wells exceeded the U.S. Environmental Protection Agency Lead and Copper Rule action level for lead of 15 μg/L. However, there is no safe level of lead exposure, as even low water lead levels-those less than 5 μg/L- can increase a child's blood lead level. In the Macon County Health Department samples they found water with lead concentrations as high as 191 μg/L.

North Carolina like most of the eastern seaboard states has areas at high risk for corrosive water. During periods of stagnation, in water that is corrosive (with a pH less than 6) a chemical redox reaction occurs that dissolves and leaches lead into the water. Lead present in well and plumbing components is leached into the water. This lead comes from brass fittings and galvanized pipe (which has a lead- zinc coating), and plumbing components produced before 2014 when "lead-free" fixtures could have up to 8% lead. In Virginia, the Blue Ridge, Piedmont and shallow wells in the Coastal Plain have a high risk for corrosive water and lead contamination in their water.

Civil and Environment Engineering Department at Virginia Tech and the Environmental Health Services Branch of the Macon County Public Health Department and lead by Kelsey J. Pieper PhD USDA-NIFA Postdoctoral Fellow at Virginia Tech investigated lead in well water concentrations at the homes of 15 private wells in Macon County found to have elevated levels of lead in their wellhead samples. There was another part of the research but we will not discuss that here.

 Low pH water can corrode metal plumbing fixtures causing lead and copper to leach into the water and causing pitting and leaks in the plumbing system. The presence of lead in pipes and fixtures becomes a bigger problem with water with a pH less than 6. In the past lead was used to solder copper pipes together before 1988 when the 1986 ban on lead in paint and solder went into effect. Also, until 2014 when the 2011 Reduction of Lead in Drinking Water Act went into effect, almost all drinking water fixtures were made from brass containing up to 8% lead, even if they carried a plated veneer of chrome, nickel or brushed aluminum and were sold as "lead free." So even home built with PVC piping in the 2000's may have some lead in most of the faucets.

The pattern of lead release and remediation for lead contamination originating from plumbing have been extensively studied. The goal for the Virginia Tech and the Macon County Public Health Department study was to identify patterns of lead leaching/ release within the well itself. Plumbing components used within a private well are not subject to the 1986 Lead Ban or the 2011 Reduction of Lead in Drinking water Act requirements. Galvanized iron is still commonly used for well casings and fittings and drop pipes in well deeper than 600 feet. Before 2014 Prime Western grade “lead free” galvanized steel zinc coating was required to contain between 0.5%-1.4% lead. After 2014, “lead free” galvanized steel have less than 0.25% lead in the surface coatings. Nonetheless, under corrosive conditions, any lead used in coatings can be easily released to the water and pumped to the household tap or accumulate in scale layers on the pipe surface or well bottom where scale can accumulate and be released or picked up and pumped with the water.

Water lead concentration patterns and sources of contamination within the wells differed among the 15 private wells as can be seen in the diagrams below which come from Environmental Science and Technology article cited below. The scientists found that elevated lead was associated with three sources of lead release: (1) dissolution of lead from well plumbing during periods of stagnation; (2) scouring of leaded scales and sediments along the well plumbing infrastructure during initial water use; and (3) mobilization of leaded scales during continued water use.

From Pieper et al.

As you can see, water lead levels measured during well testing show that in (A) nine wells had no water lead during continued water use however, (B) six wells showed sporadic spikes in particulate lead during continued water use. The detection limit of lead in the analysis was 1 μg/L. Lead contamination in a well can come from three potential sources; galvanized iron well casings, galvanized iron and brass well components, and leaded scales and sediment which have formed over time.

Corrosive water is the primary risk for lead in well water. However, over time water with a neutral pH could dissolve the coating on galvanized iron and in brass well components. The well completion reports do not document materials used for well components in Virginia or anywhere else to my knowledge. Once installed a well casing cannot be removed. It is possible to line the casing with a plastic pipe a technique used to seal a well where the grouting has failed. All the other components of the well can be replaced, though excavation would be required to replace the exterior portions of the pitless adaptor. However, scale that has accumulated on the bottom of the well might remain a source of lead if it is not mechanically removed. Further research needs to be done to further characterize the lead in well and effective remediation techniques.

To read the complete article:

Elevated Lead in Water of Private Wells Poses Health Risks: Case Study in Macon County, North Carolina

Kelsey J. Pieper, Victoria E. Nystrom, Jeffrey Parks, Kyle Jennings, Harold Faircloth, Jane B. Morgan, Jim Bruckner, and Marc A. Edwards Environmental Science & Technology 2018 52 (7), 4350-4357 DOI: 10.1021/acs.est.7b05812 

EPA Grants $1.9 Million to Virginia Tech

Yesterday, the U.S. Environmental Protection Agency (EPA) awarded $1,981,500 to Virginia Polytechnic Institute and State University (Virginia Tech) in Blacksburg, Va., to research lead in drinking water. Virginia Tech will use this funding to create a public assisted framework to detect and control lead in drinking water, working collaboratively with the public, encouraging citizen scientists to participate in the research.

Lead in drinking water is a national problem, and according to EPA Administrator Scott Pruitt it is one of the greatest environmental threats we face as a country, especially dangerous for our children. Flint Michigan was not an aberration nor was it the worst incidence of lead in drinking water supplies. Flint became famous for their lead problem because of a combination of determined residents, blatant misrepresentation by public officials, and the good luck of engaging Professor Marc Edwards of Virginia Tech. This allowed Flint to become the poster child for lead in drinking water that Washington DC failed to become ten years earlier. Last year in an examination of data, Reuters found 3,000 communities that had recently recorded lead levels at least double those in Flint during the peak of that city’s contamination crisis. Now, according to EPA Virginia Tech's research will move us one step closer to eradicating lead in drinking water.”

Lead does not exist in in most groundwater, rivers and lakes- the source water for most municipal and private water supplies. Instead, lead in drinking water is picked up from the pipes on its journey into a home. In older homes the water service lines delivering water from the water main in the street into each home were commonly made of lead. This practice began to fade by the 1950’s but was legal until 1988. Lead was also used to solder copper pipes together before 1988 (when the 1986 ban on lead in paint and solder went into effect). Also until very recently (2011 Reduction of Lead in Drinking Water Act) almost all drinking water fixtures were made from brass containing up to 8% lead, even if they carry a plated veneer of chrome, nickel or brushed aluminum and were sold as "lead-free." So even homes built with PVC piping in the 2000’s may have some lead in most of the faucets.

The nation’s water infrastructure the pipes, treatment plants and other critical components that deliver drinking water have grown old. In many of our cities water pipes installed when systems were built have only been replaced when they break. The building service lines that connect homes and businesses to the water mains are often the original lines. For decades instead of replacing lead pipes urban water companies have used chemicals to control lead and other chemicals from leaching into the water supply.

Many at the American Water Works Association and other scientists have questioned the wisdom of this strategy. Even when successful there is always some lead leaching into the drinking water. Many of us believe that there is no safe level of lead in drinking water. No amount of exposure to lead is safe. Our national goal is to eliminate exposure to lead especially for children, who are both more susceptible to lead poisoning and suffer more severe impacts. Even at very low levels once considered safe, lead can cause serious, irreversible damage to the developing brains and nervous systems of babies and young children.

According to Principal Investigator on the Project, Dr. Marc Edwards, “Our team will establish one of the largest citizen science engineering projects in U.S. history to help individuals and communities deal with our shared responsibility for controlling exposure to lead in drinking water through a combination of low-cost sampling, outreach, direct collaboration, and modeling,” Dr. Marc Edwards continued, “We will tap a growing ‘crowd’ of consumers who want to learn how to better protect themselves from lead, and in the process, also create new knowledge to protect others. Whether from wells or municipalities, we all consume water, and we can collectively work to reduce health risks.”

Interpreting Water Test Results

The Virginia Cooperative Extension (VCE) Offices in Virginia occasionally holds drinking water clinics for well, spring and cistern owners as part of the Virginia Household Water Quality Program. The VCE subsidizes the analysis cost for these clinics. Currently, samples are analyzed for: iron, manganese, nitrate, lead, arsenic, fluoride, sulfate, pH, total dissolved solids, hardness, sodium, copper, total coliform bacteria and E. Coli bacteria at a cost of $49 to the well owner. This is far from an exhaustive list of potential contaminants, but with one or two exceptions these are the most common contaminants that effect drinking water wells. These are mostly the naturally occurring contaminants and common sources of contamination: a poorly sealed well or a nearby leaking septic system, or indications of plumbing system corrosion.

There are other contaminants that can be found in ground water in certain regions that can cause illness when exposed to small amounts over long periods of time Uranium is an example. There are also nuisance contaminants for which there is not an approved EPA methodology, iron bacteria is an example. A through water analysis should be performed before any treatment is considered to make sure the selected treatment is necessary and appropriate. Wells should be tested annually for bacteria and every 1-3 years for other common contaminants especially if you install treatment systems. Groundwater is dynamic and can change over time, and it is important to make sure that any treatment is still appropriate and effective.  Water treatment systems are not an install and forget piece of equipment, they are more systems to maintain, adjust and control to keep the water within ideal parameters. Improperly treated water can be as problematic as not treating water.

 

In order to determine if treatment is necessary, water test results should be compared to a standard. The standard we use if the U.S.EPA Safe Drinking Water Act in the list to the left. There are primary and secondary drinking water standards. Primary standards are ones that can impact health and from the list above include: coliform bacteria, E. coli and fecal coliform bacteria, nitrate, lead, and arsenic. Groundwater can sometimes be contaminate from nearby or historic land use. Before a home is purchased a much more comprehensive water analysis should be performed to ensure that groundwater is not contaminated with hydrocarbons, solvents, fuels, heavy metals, pesticides.

Coliform bacteria are not a health threat itself, it is used to indicate other bacteria that may be present and identify that a well is not properly sealed from surface bacteria. The federal standard for coliform bacteria is zero, but the federal standard allows that up to 5% of samples can test positive for coliform during a month. New coliform standards are anticipated to be promulgated shortly. Fecal coliform and E. coli are bacteria whose presence indicates that the water is contaminated with human or animal wastes. Disease-causing microbes (pathogens) in these wastes can cause diarrhea, cramps, nausea, headaches, or other symptoms. These pathogens may pose a special health risk for infants, young children, and those with compromised immune systems. However, people can drink water contaminated with fecal bacteria and not notice. If your water is contaminated with coliform but not fecal coliform or E. coli, then you have a nuisance bacteria problem and the source may be infiltration from the surface from rain or snow melt. Typical causes are improperly sealed well cap, failed grouting or surface drainage to the well. Shock chlorinate the well, repack the soil around the well pipe to flow away from the well and replace the well cap. Then after the next big rainstorm retest the well for coliform. If it is still present then a long-term treatment should be implemented:  using UV light, ozonation, or chlorine for continuous disinfection.

If you have fecal coliform in the well or E. coli, your well is being impacted by human or animal waste. If there is not a nearby animal waste composting facility, then you are probably drinking water from a failed septic system- yours or your nearest neighbors. To solve this problem you need to either fix or replace the septic system that is causing the contamination or replace the well. The failing septic systems can often be identified by using tracer dyes.  While continuous disinfection will work to protect you from fecal bacteria and E. coli, be aware that if your well is being impacted by a septic system, then the well water might also have present traces of all the chemicals and substances that get poured down the drain. Long term treatment for disinfection, and micro-filtration should be implemented:  using UV light, ozonation, or chlorine for continuous disinfection, carbon filtration, and anything that is used for drinking should be further treated with a reverse osmosis systems or micro membrane system that work by using pressure to force water through a semi-permeable membrane. This is the type of system that is used to desalinate water. Large quantities of wastewater are produced by reverse osmosis systems and need to bypass the septic system or they will overwhelm that system creating more groundwater problems. Reverse osmosis systems produce water very slowly, a pressurized storage tank and special faucet needs to be installed so that water is available to meet the demand for drinking and cooking.

 Nitrate can contaminate well water from fertilizer use; leaking from septic tanks, sewage and erosion of natural deposits. The MCL for nitrate is 10 mg/L. Infants below the age of six months who drink water containing nitrate in excess of the MCL could become seriously ill from blue-baby syndrome and, if untreated, may die. Symptoms include shortness of breath and a blue ting to the skin common in blue-baby syndrome. The NO3 dissolves and moves easily through soil which varies seasonally and  over time as plants use up the nitrate over the summer. Testing in the spring will usually produce the highest levels. Nitrate may indicate contamination from septic tanks, but do not boil the water- boiling water reduces the water and actually INCREASES the concentration of nitrates. So if your water is being impacted by a septic system and you do not replace the well; distillation, reverse osmosis, or ion exchange is necessary to control the nitrate.

The EPA guidance for sulfate is 250 ppm for taste. Sulfates can clog plumbing and stain clothing and excessive levels can have a laxative effect. If you have hydrogen sulfate above 0.5 ppm you can probably smell the rotten egg smell in your water especially when the water is heated. Hydrogen sulfide naturally occurs in shale, sandstone, and near coal or oil fields. Sulfate and hydrogen sulfide are not regulated by the EPA for drinking water, they are a secondary contaminant and though extremely unpleasant, harmless to animals, but not to plumbing equipment. There is a related problem (for which there are limited methods of testing) of sulfur reducing bacteria. According to the EPA, sulfur-reducing bacteria and sulfur-oxidizing bacteria pose no known health risks. Sulfur-reducing bacteria live in oxygen-deficient environments such as deep wells, plumbing systems, water softeners, and water heaters. These bacteria usually flourish in hot water tanks and pipes. Sulfate reduction can occur over a wide range of pH, pressure, temperature, and salinity conditions and produce the rotten egg smell and the blackening of water and sediment by iron sulfide. Sulfate-reducing bacteria can cause the corrosion of iron in pipes and water systems.

The treatment method selected depends on many factors including the level of sulfate in the water, the amount of iron and manganese in the water, and if bacterial contamination also must be treated. High concentrations of dissolved hydrogen sulfide also can foul the resin bed of an ion exchange water softener. When a hydrogen sulfide odor occurs in treated water (softened or filtered) and no hydrogen sulfide is detected in the non-treated water, it usually indicates the presence of some form of sulfate-reducing bacteria in the system. Water softeners provide an environment for these bacteria to grow. “salt-loving” bacteria, that use sulfates as an energy source, may produce a black slime inside water softeners. If you have modest sulfate, but no rotten egg smell, installing a water softening system may create additional problems, especially if the system is not meticulously maintained. If you have a rotten egg smell associated with the hot water and elevated levels of sulfate on the cold water side, your hot water tank may be fouled with sulfur reducing bacteria, or the tank’s corrosion control rod may be causing the sulfur to react in the heated environment. 

Iron and manganese are naturally occurring elements commonly found in groundwater in this part of the country. At naturally occurring levels iron and manganese do not present a health hazard. However, their presence in well water can cause unpleasant taste, staining and accumulation of mineral solids that can clog water treatment equipment and plumbing.  The standard Secondary Maximum Contaminant Level (SMCL) for iron is 0.3 milligrams per liter (mg/L or ppm) and 0.05 mg/L for manganese. This level of iron and manganese are easily detected by taste, smell or appearance. In addition, some types of bacteria react with soluble forms of iron and manganese and form persistent bacterial contamination in a well, water system and any treatment systems. These organisms change the iron and manganese from a soluble form into a less soluble form, thus causing precipitation and accumulation of black or reddish brown gelatinous material (slime). Masses of mucous, iron, and/or manganese can clog plumbing and water treatment equipment. 

All systems of removing iron and manganese essentially involve oxidation of the soluble form or killing and removal of the iron bacteria.  When the total combined iron and manganese concentration is less than 15 mg/l, an oxidizing filter is the recommended solution. An oxidizing filter supplies oxygen to convert ferrous iron into a solid form which can be filtered out of the water. Higher concentrations of iron and manganese can be treated with an aeration and filtration system. This system is not effective on water with iron/ manganese bacteria, but is very effective on soluble iron and manganese. Chemical oxidation can be used to remove high levels of dissolved or oxidized iron and manganese as well as treat the presence of iron/manganese (or even sulfur) bacteria. The system consists of a small pump that puts an oxidizing agent into the water before the pressure tank. The water will need about 20 minutes for oxidation to take place so treating before a holding tank or pressure tank is a must. After the solid particles have formed the water is filtered. The best oxidizing agents are chlorine or hydrogen peroxide. If chlorine is used, an activated carbon filter is often used to finish the water and remove the chlorine taste. The holding tank or pressure tank will have to be cleaned regularly to remove any settled particles.

Fluoride occurs naturally in groundwater and in certain parts of Eastern Virginia there are very high naturally occurring levels. Fluoride is a primary water contaminant and the EPA MCL 4.0 mg/L and SMCL 2.0 mg/L. Fluoride is typically added in small quantities to public water supplies the optimum concentrations for public systems 0.8 - 1.2 mg/L. Excessive levels of fluoride can cause fluorosis or bone cancer over long term exposure. Treatment for excessive levels of fluoride in water is typically reverse osmosis which will remove all fluoride and minerals from water.

The pH of water is a measure of the acidity or alkalinity. The pH is a logarithmic scale from 0 – 14 with 1 being very acidic and 14 very alkaline. Drinking water should be between 6.5 and 7.5. For reference and to put this into perspective, coffee has a pH of around 5 and salt water has a pH of around 9. Corrosive water, sometimes also called aggressive water is typically water with a low pH. (Alkaline water can also be corrosive.) Low pH water can corrode metal plumbing fixtures causing lead and copper to leach into the water and causing pitting and leaks in the plumbing system. The presence of lead or copper in water is most commonly leaching from the plumbing system rather than the groundwater. Acidic water is easily treated using an acid neutralizing filter. Typically these neutralizing filters use a granular marble, calcium carbonate or lime. If the water is very acidic a mixing tank using soda ash, sodium carbonate or sodium hydroxide can be used. The acid neutralizing filters will increase the hardness of the water because of the addition of calcium carbonate. The sodium based systems will increase the salt content in the water.

Water that contains high levels of dissolved minerals is commonly referred to as hard. Groundwater very slowly wears away at the rocks and minerals picking up small amounts of calcium and magnesium ions. Water containing approximately 125 mg/L can begin to have a noticeable impact and is considered hard. Concentration above 180 mg/L are considered very hard. As the mineral level climbs, bath soap combines with the minerals and forms a pasty scum that accumulates on bathtubs and sinks. You either must use more soap and detergent in washing or use specially formulated hard water soap solutions. Hard water can be just a minor annoyance with spotting and the buildup of lime scale, but once water reaches the very hard level 180 mg/L or 10.5 grains per gallon, it can become problematic. Hard water spots appear on everything that is washed in and around the home from dishes and silverware to the floor tiles and cars. When heated calcium carbonate and magnesium carbonate are removed from the water and form a scale (lime scale) in cookware, hot water pipes, and water heaters.

Water softening systems are used to address the problem are basically an ion exchange system. The water softening system consists of a mineral tank and a brine tank. The water supply pipe is connected to the mineral tank so that water coming into the house must pass through the tank before it can be used. The mineral tank holds small beads of resin that have a negative electrical charge. The calcium and magnesium ions are positively charged and are attracted to the negatively charged beads. This attraction makes the minerals stick to the beads as the hard water passes through the mineral tank. Sodium is often used to charge the resin beads. As the water is softened, the sodium ions are replaced and small quantities of sodium are released into the softened water, thus the salty taste of softened water. When the water softening system is recharged the excess sodium solution carrying the calcium and magnesium is flushed to the septic system which may shorten the life of the drain field.

 At the present time the EPA guidance level for sodium in drinking water is 20 mg/L. This level was developed for those restricted to a total sodium intake of 500 mg/day and does not necessarily represent a necessary level for the rest of the population. Based on taste of the water levels of sodium should be below 30 to 60 mg/L based on individual taste. Water softening systems add sodium. Reverse osmosis systems and distillation systems remove sodium and are safe for household use, but addressing hard water by using vinegar to descale pots and dishwashers, regularly draining hot water heaters, and using detergents formulated for hard water might be a better solution for you.

Arsenic is not a common contaminant in groundwater that has not been impacted from surface runoff. Arsenic can be caused by erosion of natural deposits, but is more typically caused by runoff from orchards, runoff from glass & electronics production wastes, or leaching from coal ash disposal of or  agricultural chemical mixing areas.  The EPA standard for arsenic is 0.01 mg/L. Arsenic removal depends on the type of arsenic (there are two types) and the other contaminants present in water. Arsenic removal methods or systems include anion exchange, reverse osmosis, activated alumina, and other types of adsorptive media filters. Each method has its limitations, advantages and disadvantages and should be chosen based on additional analysis.