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.  

Is the Water Well Safe? Is the Water Well Good?

When I alerted all of the homeowners of my little neighborhood of the Prince William County Virginia Cooperative Extension (VCE) Office drinking water clinic for testing well water next week, one of my neighbors told me “I don’t have to test my water until I sell the house.” I was absolutely silenced by that comment. How do you respond to that?  In fact my neighbor does not ever have to test her water in Virginia. It is only that many mortgage companies require a basic test of water potability to close a mortgage. This most basic test of potability consists of a bacterial test and is written into most purchase contracts. My neighbor has lived in their house for 8 years with no intention of moving, so in essence she told me that she does not intend to ever test her drinking water. Because she does not “have to,” my neighbor has no intention of monitoring the most basic health risk- contaminated water. In fact a malfunctioning well (either due to contamination or component failure) can be expensive to repair or replace, but the harm from contamination is only likely to impact your family’s health and Virginia lets you do as you want. As long as the well continues to pump water you can ignore it.

The most basic water test usually performed at purchase or commissioning of a well is for total coliform bacteria. Total coliform bacteria is always present in manure and sewage, but is also present in soil and vegetation and surface water and while it may indicate that the well has been impacted by a nearby septic system or manure composting, it can also mean that surface water is getting into the well either directly through a failing casing or grouting or improper construction or well cap or by other means (karst terrain). In a world not subject to chemical contamination of the aquifer (from pesticides, herbicides, solvents and fuels present in stormwater runoff) or high natural concentrations of arsenic or metals, a coliform bacteria test is a fairly decent test to determine potential outside impact to a well and sound construction. Well water that test positive for coliform is often tested for E. coli (Escherichia coli) or fecal coliform types of coliform bacteria. E. coli or fecal coliform bacteria are present only in the digestive systems of humans and animals and a positive test result indicates contamination by animal manure or sewage. If a well tests positive for E. coli or fecal coliform the water is unsafe to drink (it is “poopie” water). Such wastes may include one or more of a variety of potentially pathogenic microorganisms such as Salmonella, Shigella, enteric viruses, Giardia or Cryptosporidium that may be present in human or animal manure and can cause severe illness. People have died from drinking water contaminated with cryptosporidium.

In Virginia and most other states, regulations for private well construction and testing apply only to newly constructed wells. In addition to various construction requirements (which include setback distance requirements from certain potential pollution sources such as septic tanks and leach fields), newly-constructed wells must be tested for the presence or absence of coliform bacteria. Although some municipalities and counties in other states have private well testing programs, only New Jersey has a statewide private well testing program which requires regular testing of private well water and treatment of the water if any of the standards are exceeded. Everywhere else in the country you are on your own to ensure that you are drinking safe and clean water.

The issue of whether water is safe to drink is separate from whether the water is free of unpleasant contaminants like iron, manganese, chloride, and low levels of sulfur or if the well can deliver adequate amounts of water.  Groundwater can change over time, become contaminated or dry up from inadequate recharge or overuse and wells do not last forever.  There are three aspects to a private well- the well and well system, the water quality and the water quantity. Failure of any of these can impact your life and the value of your home. The well is essentially a hole in the ground. Shallow wells (those less than 50 foot deep) are generally dug or bored into the ground and have larger diameters (2-4 foot). Shallow wells are more prone to contamination and drought and bored wells have the shortest life. Deeper wells are called drilled wells because they are drilled into the ground to depths from 50-450 feet or more and because of the need for drilling rigs cost much more to build. The diameter of a drilled well is 6-8 inches.

Generally, drilled wells provide a safer source of drinking water, and are less often impacted by drought. In igneous and metamorphic rock systems like the Piedmont of Virginia, the fractures and fault lines formed in the rocks store and transmit groundwater. The size and number of water bearing fractures varies and there is a wide variation in well yields from under 1 gallon per minute to over 50 gallons a minute depending on location and specific site geology. Fractures can become fouled with mineral deposits or iron bacteria or simply go dry over time. The specific geology and water quality will determine the life span of a well. Aquifers can go dry unexpectedly, but all wells will fail over time. The lifespan of a drilled well is assumed to be 20-50 years, but varies tremendously based on site specific conditions. I personally know of a drilled well that lasted almost 65 years before the well stopped producing water, but if you are buying a home with a well over 20 years old you will need to budget for drilling a new well. Make sure that is considered in the price you pay and that the property has another location to drill a well.  

The well system consists of the well, the well casing, the inlet for water, and the pumping system. The casing is the structure around the well hole to prevent its collapsing. It could be a steel or plastic casing or an open hole in the bedrock. In this part of Virginia, the Piedmont, the top of the well is lined with steel for 50 feet and then the well is open in the bedrock allowing the water to flow into the well. The well casing will rust over time. The well casing should be 1-2 feet above the land surface to make sure that during storms and flooding that nothing washes down the well. There should be no holes or cracks in the visible portion of the casing and the well cap should be tightly bolted closed.

The pumping system includes the pump, piping and electrical connections to pump water from the well into the house and a pressure tank to maintain constant water pressure in the house. Shallow wells usually use centrifugal pumps and are often located in a pump house or the basement. Drilled wells have submersible pumps. The pump and pumping systems are the most likely components to fail in a well. The average life of a submersible pump is variously reported as 12-15 years, but many pumps fail in the first few years. The essential components of a modern drilled well system are: a submersible pump, a check valve (and additional valve every 100 feet), a pitless adaptor, a well cap, electrical wiring including a control box, pressure switch, and interior water delivery system. There are additional fittings and cut-off switches for system protection, but the above are the basics and each and every component must work properly for your well to function properly.

In addition, in order for a well to keep supplying water to your home the components within the basement must all continue to work. These components provide constant water pressure at the fixtures in the house and the electrical switch that turns on the pump. The pump moves water to the basement water pressure tank, inside the tank is an air bladder that becomes compressed as water is pumped into the tank. The pressure in the tank moves the water through the house pipes so that the pump does not have to run every time you open a faucet. Bladders and electrical switches will fail over time and valves and switches and impellers on the pump can break, foul or find any number of ways to fail. You have to assume that pump systems that are older than 12 years are on borrowed time. It does not mean that a pump system cannot last 25 years or more, but I would not bet on it. Also, if your pump fails consider replacing other components of the system at the same time.

If buying a home with a well you need to consider the construction, condition, age and location of the well in addition to water quality and quantity. Make sure that the well is uphill (up gradient) and at least 50 feet (preferably 100 feet) from potential pollution sources like septic tanks, septic drain fields, stormwater drainage ditches and sources of contaminated runoff. Clay loams or silty clay soils filter pollutants and protect an aquifer. If there is not a lot of top soil and overburden or the soils are sandy, make sure that the well is deep and test the well for chemical contaminants before purchase. A shallow water table and fractured bedrock may provide larger quantities of water, but the shallow fractured rock systems are easily contaminated.

When testing your water you need to consider nearby likely sources of contamination and test for those contaminants, but the contaminants that occur in nature and from human and animal waste that can impact health need to be tested for:  E. coli or fecal coliform and total coliform, nitrate, sodium, sulphate, lead, floride and copper. In addition, water taste and aesthetics are impacted by hardness (calcium carbonate), chloride, iron, manganese and pH and you should test your water for these before you buy a home or purchase a treatment system. 

Treating Bacterial Contamination in Your Well

If bacteria are found in your water (after verification testing and chlorine shocking) the water can be disinfected. The oldest form of disinfection is chlorination. This method of water purification has been in use for about a hundred years. However, if your water supply becomes contaminated, elimination of the source of contamination is the most permanent solution. Continuous chlorination to kill disease-causing (fecal) bacteria in a contaminated water source should be a temporary measure used only until you can develop a new, sanitary water supply. If fecal bacteria have contaminated a water supply there may also be an associated increase in nitrogen which can be a significant health threat to infants. Let’s be honest here, the most likely source of fecal bacteria is a nearby septic system now focus on the source of fecal contamination and think of the yuck factor. If disease-causing bacteria enter your water supply on a continuous basis, you must eliminate the source or construct a new water supply.

Chlorination is widely used because it readily controls bacteria which may enter your well during construction, repair, flooding or as a result of improper construction. Chlorination can be appropriately used to control nuisance organisms such as iron, slime and sulfate-reducing bacteria. Iron bacteria feed on the iron in the water. They may appear as a slimy, dark-red mass in the toilet tank but microscopic examination is needed to confirm their presence. Iron bacteria colonies may break loose from the inside of pipes and flow through faucets to cause stains in laundry, plumbing fixtures, etc. Though thorough shock chlorination of the well and water system may destroy all iron bacteria colonies within the house; iron bacteria that has penetrated the water-bearing formation will be difficult to eliminate and will likely re-infest the system. In this situation you will need to repeat chlorination treatment periodically or install a continuous disinfection system.

Other nuisance organisms that chlorination can eliminate include sulfate-reducing bacteria which produce a rotten-egg odor. Nuisance bacteria do not cause disease. Proper chlorination will kill these bacteria. Finally, large amounts of iron can be removed from water by adding chlorine to oxidize the clear soluble iron into the filterable reddish insoluble form. Chlorine helps remove manganese and hydrogen sulfide in the same way. In these instances a chlorination system would be installed with a filtration system, the chlorinator first. Chlorination does have drawbacks; it will not remove nitrates from water despite the implied or direct claims of some water treatment firms. Adding chlorine may prevent nitrates from being reduced to the toxic nitrite form; however, nitrates are not removed from water by chlorination.

Chlorine in water is not poisonous to humans or animals. However, if the concentration is great enough the water will have an unpleasant taste and or smell. Some people object to the smell and/or taste of extremely small concentrations of chlorine. In those cases an activated carbon or charcoal filter may be used to remove the chlorine from the drinking water. Chlorination can also produce disinfection by products which are carcinogenic. Trihalomethanes (THMs) are organic chemicals that may form when chlorine is used to treat water supplies that contain humic compounds which are associated with decomposition of organic materials such as leaves, grass, wood or animal wastes. Lifetime consumption of water supplies with THMs at a level greater than 0.10 milligrams per liter is considered by the Environmental Protection Agency to be a potential cause of cancer. THMs can be removed from drinking water through use of an activated carbon filter.

Other methods of disinfecting water include boiling, distilling, treating with ultraviolet light and treating with ozone. Treatment with ultraviolet light and ozonation are replacing chlorination in may water treatment plants and is becoming more popular for home use. Water must be filtered before treatment with UV light. So, unlike chlorination systems, the filtration system is installed ahead of the UV treatment system. The typical single home UV system is a complete unit that includes a filtration cartridges and can be purchased as a whole house unit or an under the sink kitchen installation. UV, like distillation, disinfects water without adding chemicals. It does not create new chemical complexes, nor does it change the taste or odor of the water, and does not remove any beneficial minerals in the water. Ultraviolet devices are most effective when the water has already been partially treated, many units use filtration-sometimes both sediment and a carbon filter to clean the water prior to passing it through the UV light, which results in both disinfected and cleaner tasting water.

Drinking Water Problems with Your Private Well Part 1

First of all let me say that according to the US EPA actual events of groundwater contamination have historically been rare and typically do not occur at levels likely to pose health concerns. This fact is the basis of the EPA and state health departments’ absolute acceptance of private and unmonitored use of groundwater for drinking water purposes for a significant portion of the United States. In Virginia 34% of the population is estimated to obtain their drinking water from private groundwater wells. However, as development in our modern society increases, there are a growing number of activities that can contaminate our drinking water and increased density brings more opportunities to impact groundwater. As an environmental engineer I tended to see a lot of contaminated sites, so I tend to focus on threats to the groundwater and worry about my groundwater quality more than most.

The most common sources of pollution to groundwater supplies come from two categories; naturally occurring ones and those cause by human activities. Naturally occurring contamination are those that are produced from the underlying soil and rock geology and wildlife. Microorganisms in the soil and from wildlife can travel into groundwater supplies through cracks, fissures, other pathways of opportunity or even through sedimentary and basaltic rocks that are highly fractured and overlain by a thin cover of overburden. Nitrates and nitrites from the nitrogen compounds in the soil can also enter the groundwater. From the underlying rocks radionuclides and heavy metals can enter the groundwater. There are areas with natural occurring arsenic, cadmium, chromium, lead, selenium and fluoride.

Human activities can also introduce contaminants into the groundwater. Bacteria and nitrates can be caused by human and animal waste. In our own neighborhoods septic systems, horses, backyard poultry can cause these problems. On a regional level small lots and dense population of septic systems or large animal or fertilized farm operations can cause problems. Heavy local use of pesticides for ornamental gardens (those small suburban lots again), heavy metals from mining operations, industrial products from manufacturing and industrial operations, leaks from underground storage tanks, solvents from automotive and airplane maintenance or dry cleaning operations. Landfills and household waste can introduce solvents, motor oil, and paint, paint thinner, water treatment chemicals and others.

It is cost prohibitive to test for every potential contaminant. To know what type of contaminants might be impacting your well a simple rule of thumb is to look out from your property. What you can see is likely to be the source of human contaminants to your drinking water well. Though some will see large farming operations, factories, military and industrial operations, gas stations, mining operations, most private well owners will see neighbors. Your and your neighbors septic systems, a few horses or dogs, maybe backyard poultry, lawns that have been fertilized (or over fertilized) and houses that may have been sprayed for termites.

You can not taste bacterial contamination from human and animal waste and you can not taste nitrate nitrite contamination. You can even grow accustomed to low levels of bacterial contamination, so that it is only house guests who develop intestinal disorders. Since bacterial contamination cannot be detected by taste, smell, or sight, all drinking water wells should be tested at least annually for Coliform bacteria and E Coli. Due to the extra cost (under $20) most health departments only recommend total coliform testing. Total coliform counts give a general indication of the sanitary condition of a water supply. Total coliform includes bacteria that are found in the soil, in water that has been influenced by surface water, and in human or animal waste. Fecal coliform is the group of the total coliform that is considered to be present specifically in the gut and feces of warm-blooded animals. E. coli is considered to be the species of coliform bacteria that is the best indicator of fecal pollution and the possible presence of pathogens.

Most state’s well construction code requires all new, repaired, or reconditioned wells to be disinfected with chlorine to kill bacteria that may have been introduced during construction. Testing is required initially to demonstrate that the water is free of Coliform bacteria before the well is put into service. Bacteria can be introduced into a new well during construction and can remain if the water system is not thoroughly disinfected and flushed. Well construction defects such as insufficient well casing depth, improper sealing of the space between the well casing and the borehole, corroded or cracked well casings, and poor well seals or caps can allow sewage, surface water, or insects to carry coliform bacteria into the well. Unplugged abandoned wells can also carry coliform bacteria into deeper aquifers. In an existing well system that formerly was bacteria free look for defects. All wells should be Coliform free when initially put into service. However, be aware that and unscrupulous well driller (or home seller) could test immediately after shocking the system with chlorine and in that way obtain a bacterial free sample of a well.

If the bacterial contamination is only Coliform bacteria and not E. coli, be sure to inspect the well for defects, check the grouting, casing, and clean the water delivery system and filter of slime and flush the system fully. Then retest. If the system passes let a few weeks go by and retest again. If repairing and cleaning the system does not solve the problem then one of the long-term solutions will have to be implemented. This includes continuous disinfection and replacing the well. Be aware that whole house filters, water softening systems for hard water do not remove bacteria or nitrate/nitrite from water. A reverse osmosis system can remove nitrate/nitrite from water.

If you do have a bacterial problem, fix it. There are four types of water treatment that can be easily and inexpensively used to remove bacteria. They are chlorination, ozonation, ultraviolet light, and heat. Chlorination is the most commonly used means of disinfection in private water systems. High chlorine concentrations can have objectionable tastes and odors, and even low chlorine concentrations react with some organic compounds to produce strong, unpleasant tastes and odors. To eliminate the excessive amounts of chlorine, the water is then dechlorinated. Activated carbon filters are the most common devices used to dechlorinate water, remove objectionable chlorine tastes, and reduce corrosion of plumbing systems. In addition to removing taste and odor problems, granular activated carbon absorption is a good method to remove other impurities including some pesticide residues, and radon. Boiling water will kill bacteria, but be aware if bacterial contamination is being caused by leaking septic or animal waste, you might also have a nitrate/nitrite problem (which can be lethal to infants) and boiling water concentrates the nitrate/nitrite. Also chlorine and UV light water treatment systems do not remove nitrate/nitrite.

Excessive levels of these nitrogen compounds in drinking water have caused serious illness and sometimes death in infants less than six months of age. This condition results when nitrate is converted to nitrite in the infant’s body. Nitrite then interferes with the oxygen carrying capacity of the blood. Symptoms include shortness of breath and blueness of the skin (methemoglobinemia). This is an acute disease in which symptoms can develop rapidly in infants from very minor exposure. So, if you well water contains bacteria, before you decide on a treatment option, test for nitrate/nitrite. If there is excessive nitrogen compounds it is important that you install a reverse osmosis system on the drinking water tap used to mix baby formula or make up bottles (and make coffee and food preparation for that matter). Under counter reverse osmosis systems generate 3-5 gallons of waste water for each gallon of treated water depending on the system.

Sometimes the installation of a new well may produce water with less nitrate and nitrite and bacteria, but is best to determine the source of contamination before a new well is installed. The new well would need to draw water from a different geologic horizon in order for it to have a reasonable chance of avoiding or lowering the contamination. To help determine whether a new well could produce better quality water the sampling of similar wells in the immediate neighborhood could assist in measuring the extent of the contamination present.