Water Contaminants — Simplified

Contaminated water can often look, smell and taste fine, so it is important to have your drinking water tested to identify and address potential health risks or aesthetic issues.

And then what? What does the analysis mean to you — about your family’s health, or your home’s infrastructure?

We have been constantly reviewing federal, state and local regulations, medical research and water industry guidelines to simplify “all you need to know” about common water quality contaminants for your easy access.

Each section below covers the health effects, regulatory limits, common sources, and prevention or treatment considerations for many commonly found drinking water contaminants.

Health Effects

Acute exposure to arsenic can cause nausea, vomiting, neurological effects, cardiovascular effects and decreased production of red and white blood cells, which may result in fatigue. Chronic exposure to arsenic can cause changes in skin coloration and thickening, as well as an increased risk of skin, bladder and lung cancer. Chronic exposure to arsenic in drinking water – even below regulatory limits – has also been associated with deficits in children’s cognitive and motor functions.

Regulatory Limit – Health-Related

The US EPA Maximum Contaminant Level (MCL) to prevent health problems from arsenic is 0.010 mg/L. EPA’s MCL Goal for arsenic in drinking water is zero/0 mg/L. New Hampshire DES has lowered its MCL for arsenic to 0.005 mg/L, effective July 2021. When the arsenic level is between 50%-100% of the MCL, we recommend conducting quarterly water quality sampling until the result is consistently below the drinking water limit (in accordance with MassDEP requirements for public water supplies).

Common Sources

Arsenic occurs naturally in soil and bedrock; however, contamination can also be caused by pesticides used on apple orchards, as well as wood preservatives.

Taste & Odor

Arsenic has no smell, taste or color when dissolved in water, even in high concentrations, so only laboratory analysis can detect its presence and concentration.

Prevention/Treatment Considerations

Treatment options for removing arsenic from drinking water include reverse osmosis (RO) with pre-oxidation, distillation and specialty media such as iron-enhanced ion exchange resins.

There are two variations of arsenic in water: Arsenic III (or 3+) and Arsenic V (5+). The numbers III and V describe the valence of the arsenic in the molecule when the arsenic compound is dissolved in water. Arsenic V (5+) is generally easier to remove from water than Arsenic III (3+).

Total Coliform and E. coli Bacteria
Health Effects

Coliform bacteria themselves are unlikely to cause illness; however, their presence in drinking water indicates that disease-causing organisms (pathogens) could be in the water system.

E. coli bacteria are a pathogenic strain of bacteria that can cause illness with symptoms including severe stomach cramps, diarrhea and vomiting.

Regulatory Limit – Health-Related

The US EPA Maximum Contaminant Level (MCL) for both Total Coliform and E. coli bacteria is 0 or Absent.

Common Sources

Total coliform bacteria do not occur naturally in groundwater, but are common in the environment (soil or vegetation).

E. coli bacteria do not occur naturally in groundwater, and are most commonly found in the intestines of animals and humans. Their presence in water is a strong indication of recent sewage or animal waste contamination.

The presence of Total Coliform and/or E. coli indicates there is a potential pathway or breach that allows contaminated water to enter the well water system (e.g., unsealed/unsanitary well cap, cracked well casing, standing water near well head, shallow well).

Taste & Odor

In water, bacteria alone have no smell, taste or color, so only laboratory analysis can detect its presence.

Prevention/Treatment Considerations

A first line of defense against bacterial contamination is shock disinfection. If bacterial contamination persists, continuous disinfection, such as UV disinfection, should be considered.

Health Effects

Chronic (long-term) inhalation exposure of humans to chlordane can permanent alterations of nervous system function, including problems with memory, learning, thinking, sleeping, personality changes, depression, numbness in the extremities, headache, and sensory and perceptual changes. It has been suggested that chronic exposure can cause blood disorders, but these disorders were not shown to have an increased incidence in heavily exposed groups of workers. Besides blood disorders, jaundice has been reported in persons living in homes treated with chlordane for termite control, but liver-function tests were normal in workers who manufactured chlordane. Chronic exposures may be more serious for children because of their potential longer latency period.

Regulatory Limit – Health-Related

The US EPA Maximum Contaminant Level for chlordane is 2.0 µg/L.

Common Sources

Chlordane is a pesticide/chemical compound that was commonly used for termite-treatment of approximately 30 million homes until it was banned in 1988. The pesticide was applied underground around the foundation of homes, and may be found in the air in these homes for many years after treatment. The most common exposure to chlordane is through ingesting chlordane-contaminated foods; however, exposure is also possible from digging in contaminated soil. According to the Centers for Disease Control and Prevention (CDC), chlordane is rarely detected in drinking water.

Taste & Odor

Chlordane has little to no smell and its appearance can range from colorless to amber. Only laboratory analysis can detect its presence and concentration.

Prevention/Treatment Considerations

Chlordane can be removed from water using granular activated carbon filtration.

System Effects

Over time, chlorides’ high corrosivity can damage plumbing, appliances, and water heaters. Although chlorides are harmless at low levels, well water high in sodium chloride can damage plants if used for gardening or irrigation.

Regulatory Limit – Aesthetic

The US EPA Secondary Maximum Contaminant Level (non-enforceable guideline) for chloride is 250 mg/L.

Common Sources

Chlorides typically enter surface and groundwater from both natural and anthropogenic sources, such as run-off containing road salts, discharge from water softeners, the use of inorganic fertilizers, landfill leachates, septic tank effluents, and seawater intrusion in coastal areas.

Nuisance: Taste & Odor

Chloride concentrations in excess of 250 mg/L can give rise to detectable taste in water.

Prevention/Treatment Considerations

Chlorides can be easily removed from water with reverse osmosis (RO) or distillation.

Chlorine and Total Trihalomethanes (TTHM)
Health Effects

Chlorine in drinking water has been linked to increased risk of bladder, rectal and breast cancer. Chronic exposure to chlorination byproducts, total trihalomethanes (TTHM), of which chloroform is one, can result in adverse effects on the central nervous system, liver, kidneys and heart, as well as increased risk of cancer; studies have shown that pregnant women exposed to TTHMs from chlorinated tap water face a higher risk of miscarriage and birth defects in their newborns.

An important pathway for exposure to chlorine from water is by inhaling chlorine vapors created during showering/bathing, food preparation and other running-water activities. Inhaled chlorine can cause respiratory irritation.

Regulatory Limit – Health-Related

The US EPA Maximum Residual Disinfection Level (MRDL) for chlorine is 4.0 mg/L. The US EPA Maximum Contaminant Level (MCL) for the sum total of TTHM is 80 ug/L.

Common Sources

Chlorine is commonly used as a disinfectant in drinking water supplies. TTHMs are disinfection by-products created when chlorine reacts with naturally-occurring organic and inorganic matter in the water; the four regulated TTHMs are chloroform, bromoform, bromodichloromethane and dibromochloromethane.

Prevention/Treatment Considerations

Chlorine and TTHMs can be removed from drinking water by granular activated carbon or reverse osmosis filtration. (Note that a simple Brita filter is not effective in removing TTHMs.)

Health Effects

Chronic exposure to chloroform is associated with effects on the liver, kidney, and central nervous system depression.

Regulatory Guidelines – Health-Related

The US EPA regulates chloroform as one of a group of disinfection byproducts called Total Trihalomethanes (TTHM). The Maximum Contaminant Level for the sum of the concentrations of the TTHMs is 0.08 mg/L (80 ug/L). The EPA Maximum Contaminant Level Goal and MassDEP ORS Guideline for chloroform in non-chlorinated water supplies is 0.070 mg/L (70 ug/L).

The California Office of Environmental Health Hazard Assessment’s proposed public Health Goal for chloroform is 0.4 µg/L.

Common Sources

Most commonly, chloroform is produced as a by-product of well/water system disinfection when chlorine reacts with naturally-occurring organic and inorganic matter in the water. Chloroform may also be found in the environment (water and soil) as a result of industrial activity, such as from chemical companies, paper mills, waste water from sewage treatment plants, or from leakage from chlorinated pools or septic systems.

Taste & Odor

Chloroform is colorless and has a pleasant, non-irritating odor with a slightly sweet taste.

Prevention/Treatment Considerations

Chloroform, as with other TTHM, can be removed from drinking water using activated carbon filters (faucet-mount or plumbed in; pitcher and dispenser filters are not effective for TTHM removal) or reverse osmosis.

Aesthetic Effects

Color by itself is a strictly aesthetic concern.

Regulatory Limit – Health-Related

The US EPA Secondary Maximum Contaminant Level (non-enforceable guideline) for color is 15 C.U.

Common Sources

Color may be indicative of dissolved organic material, inadequate treatment, and the potential for the production of excess amounts of disinfectant by-products. Inorganic contaminants such as metals (e.g., iron) are also common sources of color.

Prevention/Treatment Considerations

Treatment of color depends on the source of the color; if the color is from iron, manganese or copper, treatment methods designed for those contaminants should be used. Otherwise, color can usually be removed from drinking water by granulated activated carbon (GAC) filters.

Health Effects

While a small amount of copper is essential for good health, short-term exposure to high levels of copper — especially among young children — can cause vomiting, diarrhea and stomach cramps. Long-term exposure to copper can cause anemia as well as liver and kidney damage.

Regulatory Limits – Health And Aesthetic-Related

The US EPA Maximum Contaminant Level Goal (MCLG) and Action Level to prevent health problems from copper is 1.3 mg/L. When copper levels exceed the Action Level, one or more of the following actions should be taken: (1) treatment of the source, (2) corrosion control, (3) replacement of service lines, and/or (4) public education. The US EPA has also established an aesthetic, non-enforceable Secondary Maximum Contaminant Level (SMCL) of 1.0 mg/L related to taste and staining.

Common Sources

Corrosion of pipes, faucets and other plumbing fixtures due to low pH water is the most common source of copper contamination in American homes (90% of which utilize copper pipes). Running your water for a minute before drinking or cooking can reduce copper buildup at the tap.

Nuisance: Taste & Staining

Above 1 mg/L, copper can cause a distasteful metallic flavor in your water and leave a blue-green staining on fixtures.

Prevention/Treatment Considerations

Always use cold water for drinking and cooking. Run the water for 1 minute before drinking or cooking to reduce copper buildup at the tap. Ensure source water is treated to a pH greater than 6.5. Point-of-use treatment options for removing copper include reverse osmosis (RO), ultra-filtration, distillation or ion exchange.

Health Effects

High levels of fluoride in drinking water can cause bone disease and dental fluorosis.

Regulatory Limit – Health-Related

The US EPA Maximum Contaminant Level (MCL) to prevent health problems from fluoride is 4.0 mg/L. The US EPA Secondary Maximum Contaminant Level (non-enforceable guideline) to prevent dental fluorosis is 2.0 mg/L.

Common Sources

Fluoride in drinking water is commonly eroded from natural deposits; used as a fertilizer, used in aluminum industries and also commonly added to public drinking water as an additive to protect teeth.

Prevention/Treatment Considerations

Point-of-use treatment options for removing fluoride include reverse osmosis (RO) and distillation.

Gross Alpha Radiation
Health Effects

Chronic exposure to high levels of Radium 224 and 228 has been associated with an increased risk of bone cancers; exposure to Radium 226, with bone cancers and cancers of the head sinuses. Long-term exposure to uranium increases the risk of kidney damage. While Gross Alpha Radiation cannot pass through the skin, once ingested, radioactive particles ionize nearby atoms in the body, damaging chromosomes or other cell parts and can lead to the death or unnatural reproduction (cancer) of the cell.

Regulatory Limit – Health-Related

For both public and private water supplies (private wells), the Maximum Contaminant Level (MCL) is 15 pCi/L. Because there is no safe level of radiation exposure, the Maximum Contaminant Level Goal (MCLG) for Gross Alpha Radiation has been set at 0 pCi/L.

  • If the Gross Alpha level exceeds 15 pCi/L, treatment is strongly advised; in addition, the water supply must be sampled quarterly, until four consecutive samples show Gross Alpha levels below the MCL.
  • However, if Gross Alpha levels are between 5 pCi/L and 15 pCi/L, further testing is recommended to measure/quantify Radium 226 and Radium 228 levels in the water.
  • If combined Radium levels exceed 5 pCi/L, treatment is recommended.
Common Sources

Gross Alpha, the combined alpha particle radioactivity from Radium and Uranium, are naturally occurring radioactive substances commonly found in Massachusetts geological formations and are transmitted to groundwater as groundwater passes through and breaks down the bedrock.

Treatment Considerations

Reverse osmosis and distillation have been proven effective in removing gross alpha radiation from drinking water.

Infrastructure/System Effects

While hard water does not generally pose a health hazard, hard water can be a nuisance and lead to costly repairs to water-using appliances and plumbing. For example, the scale deposited by hard water can:

  • clog pipes and reduce water flow
  • decrease the efficiency of toilet flushing unit by 70% and water taps by 40%
  • coat and spot the insides of tea/coffee pots
  • clog and shorten the life of water heaters
  • increase utility bills, due to accumulated scale in the water heater (Scale is a poor conductor of heat, increasing the energy needed to heat water.)

Additionally, hard water requires more soap and synthetic detergents for laundry and washing, makes it more difficult to rinse soap from skin, and may leave hair rougher and harder to untangle.

Hard water is not a health hazard. In fact, hard drinking water generally thought to contribute a small amount toward total calcium and magnesium human dietary needs.

Regulatory Limit

There is no regulatory limit for hardness.

Degrees Of Hardness
Degree of Hardnessmg/L (or ppm)Grains per Gallon (gpg)
Slightly Hard17.1 – 601.0 – 3.5
Moderately Hard60 – 1203.5 – 7.0
Hard120 – 1807.0 – 10.5
Very Hard>180>10.5
Common Sources

Hard water is caused by water dissolving naturally-occurring geologic calcium and magnesium and carrying them into the groundwater supply.

Prevention/Treatment Considerations

An ion exchange water softener can treat hard water by exchanging the scale-producing calcium and magnesium with sodium or potassium from added salts. Additionally, conventional water softeners can be effective for removing iron and small amounts of manganese.

Health Effects

Iron in well water does not usually pose health risks, however, iron may present some concern if certain bacteria have entered a well, since some pathogenic organisms require iron to grow and the presence of iron particles makes elimination of the bacteria more difficult; conversely, elimination of bacterial iron film is also more difficult.

Regulatory Limit – Aesthetic

The US EPA Secondary Maximum Contaminant Level (non-enforceable guideline) for iron is 0.3 mg/L.

Common Sources

Iron comes from natural sources like bedrock and soil and from rusting pipes and water fixtures.

Nuisance: Taste, Staining & Buildup

Water with less than 1 mg/L of iron can cause staining on plumbing fixtures (e.g., sinks, tubs, toilet bowls) and laundry, clog wells, pumps and water-using appliances (such as dishwashers). At moderate concentrations iron will give water an unpleasant metallic taste.

The presence of iron in well water can also result in iron bacteria. These non-pathogenic bacteria feed on iron in water and form red-brown slime in toilet tanks, can clog water systems and often cause sulfur odors.

Prevention/Treatment Considerations

Treatment options for removing iron from well water include water softening, oxidation filtration and point-of-use reverse osmosis. Removal of colloidal iron, which is comprised of very small particles, is more complicated, requiring flocculation or ultrafiltration.

Iron bacteria can be controlled with disinfection/shock chlorination; however, it is almost impossible to kill all the iron bacteria in the water system. They may eventually grow back, requiring repeated treatment. If bacteria re-growth is rapid, installation of a continuous disinfection system would be recommended.

Health Effects

Lead accumulates in the body and has multiple toxic effects on the brain, liver, kidney and bones. Children are especially vulnerable to lead poisoning, in particular, which damages the brain and nervous system, leading to behavior and learning problems, lower IQ and hyperactivity, slowed growth, hearing problems and anemia. Adults exposed to lead can suffer from cardiovascular effects, decreased kidney function and reproductive problems.

Regulatory Limit – Health Related

The US EPA Maximum Contaminant Level (MCL) for lead in drinking water is 0.015 mg/L; however, no amount of lead is considered safe. EPA’s MCL Goal for lead in drinking water is zero/0 mg/L.

Common Sources

Lead is a heavy metal that most often enters your water by corrosion of aging pipes, household plumbing systems, from the erosion of natural deposits nearby and by industrial activity waste streams. Changes in water chemistry (pH) can have a substantial impact on the release of lead into your water.

Taste & Odor

Lead has no smell, taste or color when dissolved in water, even in high concentrations, so only laboratory analysis can detect its presence and concentration.

Prevention/Treatment Considerations

First, try to identify and remove the lead source (well, pump, lead pipes, lead solder used to join copper pipes, brass in faucets, coolers and valves). If not possible or cost-effective to remove the source, ensure water pH is maintained between 6.5 and 8.5 to avoid causing corrosion and drawing lead from plumbing components. Avoid cooking or drinking hot tap water, and flush the system by running the water for 1-2 minutes before using it.

Treatment options for removing lead from well water include reverse osmosis, distillation and carbon filters specially designed for lead removal. Typically, these methods are used to treat water at only one faucet.

Health Effects

While small amounts of manganese are necessary for health, exposure to high levels of manganese has been associated with toxicity to the nervous system, producing a syndrome that resembles Parkinson’s Disease. Young children appear to absorb more manganese than older age groups but excrete less; a growing number of studies report associations between manganese exposure and hyperactivity, lower IQ scores, and memory and attention problems in children.

Regulatory Limit
  • Aesthetics-Related: The US EPA Secondary Maximum Contaminant Level (non-enforceable guideline) for manganese in drinking water is 05 mg/L.
  • Health Related: US EPA set a Lifetime Health Advisory at 3 mg/L, an Acute 10-Day Health Advisory at 1 mg/L, and an Acute 10-Day Health Advisory at 0.3 mg/L for infants younger than 6 months; these are also non-enforceable guidelines.
Common Sources

Manganese is a naturally occurring mineral found in food, water and soil. Manganese is also an additive in unleaded gasoline, pigment, plumbing materials, battery cells, matches, fireworks, and fertilizer. It acts as a reagent in organic chemistry and as an oxidizing agent.

Nuisance: Taste, Odor And Staining

Water with manganese above 0.05 mg/L may have a metallic taste and brownish-red color. High levels of manganese can stain fixtures and clothing.

Prevention/Treatment Considerations

Treatment options for removing manganese from well water include water softening, oxidation filtration and point-of-use reverse osmosis.

Health Effects

The EPA nitrate limit of 10 mg/L was established in 1962 to prevent acute cases of “blue baby syndrome” (methemoglobinemia) in which ingestion of nitrate compromises the ability of an infant’s blood to carry oxygen. Pregnant women, people with reduced stomach acidity, and people with certain blood disorders may also be susceptible to nitrate-induced methemoglobinemia.

More recent studies. such as by the National Cancer Institute, consistently find that ingestion of nitrate from drinking water, especially in the range of 5 to 10 mg/L, increases the risk of colon, kidney ovarian and bladder cancers. These risks are higher for people with low vitamin C intake, high consumption of red meat, and for smokers. Additionally, women consuming nitrate-contaminated water face a greater risk of thyroid cancer.

Regulatory Limit – Health Related

The US EPA Maximum Contaminant Level (MCL) for nitrate in drinking water is 10 mg/L. When nitrate levels are between 50%-100% of the MCL, we recommend conducting quarterly water quality sampling until the result is consistently below the drinking water limit (in accordance with MassDEP requirements for public water supplies).

Common Sources

Nitrate can occur naturally in surface and groundwater at a level that does not generally cause health problems. However, high levels of nitrate in well water often result from improper well construction or damage, well location, septic system leakage, sewage, overuse of chemical fertilizers, or improper disposal of human and animal waste.

Taste & Odor

You cannot see, taste or smell nitrate in your drinking water.

Treatment Considerations

Nitrate can be removed from drinking water by three methods: distillation, reverse osmosis, and ion exchange. Note that carbon adsorption filters, mechanical filters of various types, and standard water softeners do not remove nitrate-nitrogen.

Aesthetic/System Effects

While odor is most often a nuisance, odor can be a first indication of water quality problems, particularly bacterial contamination. The most common odors in well water are sulfurous (hydrogen sulfide/rotten eggs) or earthy/musty; odors can also be salty or metallic, or like chemicals. One common source of odor is hydrogen sulfide dissolved in water, which can corrode plumbing metals, such as iron, steel, copper, and brass and exposed metal parts in washing machines and other water-using appliances. The corrosion of iron and steel from hydrogen sulfide forms ferrous sulfide or “black water” which can darken silverware and discolor copper and brass utensils. Hydrogen sulfide can also interfere with the effectiveness of water softeners and filter systems.

Regulatory Limit – Health-Related

The US EPA Secondary Maximum Contaminant Level (non-enforceable guideline) for odor is 3 T.O.N.

Common Sources

Sources of odor include: high mineral content (iron, manganese, copper) in the water which feeds iron or sulfur bacteria and creates hydrogen sulfide (H2S); bacteria or algae in sink drains, plumbing or the hot water tank; or chemical contamination.

Prevention/Treatment Considerations

If the suspected odor source is bacterial contamination, disinfection/chlorination of the well and water system is advised. Other options include aeration and activated carbon filtration.

Per- and Polyfluoroalkyl Substances (PFAS)
Health Effects

PFAS exposure has been linked to low birthweight infants, intellectual developmental delay, increased cancer risk, immune system and thyroid hormone disruption, increased cholesterol levels, and kidney and liver disease.

Regulatory Limit – Health-Related

While no Federal regulatory limits for PFAS in drinking water have been set, EPA has set an Advisory Limit of 70 ppt (0.07 ug/L) – this is for the sum of the concentrations of five PFAS chemicals found in the water. Other states have adopted different recommendations:

  • MassDEP Office of Research and Standards Guideline – 20 ppt (sum of PFOS, PFOA, PFNA, PFHxS, PFHpA and PFDA)
  • Vermont Advisory Levels – 20 ppt (sum of PFOA, PFOS, PFNA, pFHxS and PFHpA)
  • NH DES Maximum Contaminant Levels – 12 ppt PFOA, 15 ppt PFOS, 11 ppt PFNA, 18 ppt PFHxS (these levels are currently under an injunction and not enforceable as of December 31, 2019)
  • California Notification Level – 6.5 ppt PFOS and 5.1 ppt PFOA
  • New Jersey
    • Maximum Contaminant Levels – 13 ppt PFNA, 14 ppt PFOA, 13 ppt PFOS
    • Interim Groundwater Quality Standards – 10 ppt PFOA, 10 ppt PFOS

The Agency for Toxic Substances and Disease Registry (ATSDR) has set Minimal Risk Levels – an estimate of the amount of chemical a person can eat, drink or breathe each day without a detectable risk to health – for selected PFAS analytes:

  • PFOA: 78 ppt (adult) and 21 ppt (child)
  • PFOS: 52 ppt (adult) and 14 ppt (child)
  • PFHxS: 517 ppt (adult) and 140 ppt (child)
  • PFNA: 78 ppt (adult) and 21 ppt (child)

The Environmental Working Group (EWG), in its own set of drinking water standards based solely on protecting health, has proposed a standard of 1.0 ppt for each of the following PFAS analytes: PFBS, PFHpA, PFHxS, PFNA, PFOS and PFOA.

Common Sources

Exposure through drinking water has become an increasing concern because PFAS do not break down easily in the environment and can accumulate in groundwater. Such contamination is typically localized and associated with a specific facility, for example a military installation or airfield which used the chemicals for firefighting. PFAS may also be present in the environment due uncontrolled local waste dumping (e.g., food wrappers, disposed carpet), or localized used of aqueous fire-fighting foam (AFFF) on vehicle accidents on highways or roads.

Perfluoro-octanoic acid (PFOA) and Perfluoro-octane-sulfonic acid (PFOS) (the most widely used PFAS), have been used extensively in common household products such as nonstick pans, food packaging (pizza boxes, microwave popcorn bags, etc.), clothing and upholstery protectors (GoreTex, Scotchgard, etc.), and some cosmetics.

Prevention/Treatment Considerations

Granular activated carbon (GAC) and high-pressure membranes (reverse osmosis/RO) have been shown to be effective at removing PFAS from drinking water.

Infrastructure/System Effects

Water with low pH (below 6.5, acidic) can corrode (wear away) household plumbing, including water treatment systems, pipes, faucets, and the pressure tank, and leach metals such as copper, lead, cadmium, and zinc from the well pump and plumbing system; long-term exposure to corrosive water will noticeably shorten the life of water treatment systems and household plumbing and appliances. Additionally, if these leached metals are present in drinking water in amounts higher than levels set by the U.S.EPA, they can lead to health problems and unnecessary costly repairs.

Water with high pH (above 8.5, alkaline) can cause aesthetic problems, such as an alkali taste (like baking soda) to the water that makes coffee taste bitter; scale build-up in plumbing; and lowered efficiency of electric water heaters. Additionally, an overall excess of alkalinity in the body may cause gastrointestinal issues (lowers natural stomach acidity) and skin irritations.

Regulatory Limit – Health-Related

The US EPA Secondary Maximum Contaminant Level (non-enforceable guideline) for pH is 6.5 – 8.5 S.U.

Common Sources

Common causes for acidic water are acid rainfall due to atmospheric carbon dioxide and other airborne pollutants, natural geological composition, agricultural or industrial runoff and decomposition of plant materials.

Prevention/Treatment Considerations

pH can be adjusted using an acid neutralizing filter or chemical feed pump system.

Health Effects

In health people with normal kidney function, high dietary potassium intakes do not pose a health risk. However, increased exposure to potassium could result in significant health effects in people with kidney disease or other conditions, such as heart disease, coronary artery disease, hypertension, diabetes, and adrenal insufficiency, as well as those taking medications that interfere with the normal handling of potassium in the body. in people with impaired urinary potassium excretion due to chronic kidney disease or the use of certain medications, consumption of high potassium can cause fatigue, nausea, muscle pain/cramps, trouble breathing, unusual heartbeat and chest pains, and, ultimately, heart attack.

Health-Related Guideline

There is no regulatory limit for potassium in drinking water. However, for high-risk individuals, potassium intake is typically limited to about 2,000 mg/day.

Common Sources

Potassium occurs naturally in the environment, but not found in drinking water at levels that could be a concern to health individuals. Water softeners using potassium chloride salts (often used as a substitute for sodium chloride salts, for sodium-sensitive households) can significantly increase exposure to potassium at levels dangerous to at-risk individuals. For example, water softened using potassium salts can contribute between 150 and 400 mg/L potassium; for an individual consuming 2 liters of water/day, that could amount to 300-800 mg of potassium per day.

Prevention/Treatment Considerations

Potassium may be removed from water using reverse osmosis (RO). Alternatively, it may be possible to have a proportion of the intake water bypass the softener and dedicated for drinking/cooking.

Radon in Water
Health Effects

Long-term exposure to radon is known primarily to increase the risk of lung cancer from breathing radon in air (95% of radon exposure is from indoor air); there is also an extremely small risk of stomach cancer from consuming water containing radon (1% of radon exposure is from water).

Regulatory Limit – Health-Related

The MassDEP Action Limit for radon in water is 10,000 pCi/L. When radon-in-water concentrations exceed this level, indoor air should be tested.

When the radon-in-water level is between 50%-100% of the Action Limit, we recommend conducting quarterly water quality monitoring (retesting) until the result is consistently below the Action Limit (in accordance with MassDEP requirements for public water supplies).

Common Sources

Radon is a naturally-occurring radioactive gas that is formed from the breakdown of uranium in the ground and can dissolve and accumulate in groundwater. As radon is released from water though running water activities – such as running tap water, bathing/showering, and cleaning – it can raise the radon level of the air within a living space.

Prevention/Treatment Considerations

Note that the first line of action when radon-in-water levels exceed the Action Level is to measure radon-in-air levels in the basement (to quantify the amount of airborne radon entering the home as soil-gas) and a living area. This will help determine whether the waterborne radon is a significant source of radon to overall exposure.

However, if water is determined to be a significant source of radon, the most effective treatment you can apply is to remove radon from the water where it enters the home. This is called point-of-entry treatment. There are two types of point- of-entry devices that remove radon from water:

  • Aeration devices (which bubble air through the water and carry radon gas out of the system through a vent/exhaust fan).
  • Granular activated carbon (GAC) filters (radon attaches to the carbon and leaves the water free of radon). GAC filters tend to cost less than aeration devices, however, radioactivity collects on the filter, which may cause a handling hazard and require special disposal methods for the filter.

The best way to evaluate overall radon exposure – from water and air – is to conduct a long-term radon-in-air test in the basement and in a living area. Note that the EPA Action Level for radon in air is 4 pCi/L.

New Hampshire DES has issued a public health advisory for private wells specifying that when radon in water is below 4,000 pCi/L, radon in water and air should be retested every three to five years. For radon concentrations between 2,000 and 10,000 pCi/L, if air concentrations exceed 4 pCi/L, treatment of water may be advisable. For radon concentrations greater than 10,000 pCi/L, treatment of water is recommended in conjunction with mitigation of indoor air radon.

Health Effects

Sediment does not, in itself, pose health risks, rather, sediment particles can be convenient vehicles to carry pollutants and pathogens into your water supply. Potential health contaminants include microbes such as bacteria, virus, and protozoa; from pollutants such as fertilizers and pesticides; and from dissolved metals like mercury, lead, and arsenic.

Infrastructure Impact

Sediment in well water can cause wear to plumbing, pumps, and water appliances or even create clogs throughout the water system to reduce the flow of water.


There is no enforceable guideline for sediment in drinking water.

Common Sources

Sediment can enter the water supply from a number of sources:

  • Older wells, or wells drilled in loose bedrock, may experience sediment piling up at the bottom of a well, which might then be pumped into the plumbing system.
  • Damaged or degraded well components, including casing, screens, and seals can create pathways that allow sediments to enter the well.
  • Dissolved minerals, like calcium or magnesium (hardness), iron or manganese can precipitate out and develop into a white scale build-up or orange/brown staining on your fixtures or appliances.
  • Organic matter, including iron and sulfur bacteria, can build up on well components and fixtures.

Sediments may appear in well water as color or cloudiness which may or may not settle on the bottom of containers (suspended and/or dissolved solids).

Prevention/Treatment Considerations

Sediment can be removed using simple cartridge sediment filters. Other options for persistent sediment problems include spin-down filter strainers, backwashing media filters or ultra-filtration (UF) membrane systems.

Health Effects

Sodium in drinking water does not normally present health risks, as about 99% of the daily salt intake is from food and only about one percent from water. However, sodium at levels greater than 20 mg/L in well water may pose a health risk to individuals with hypertension, heart or liver disease or are otherwise on a sodium-restricted diet.

Regulatory Guidelines – Health-Related
  • US EPA and MassDEP have established a 20 mg/L advisory level for individuals with heart issues or hypertension on a very low sodium diet (500 mg/day). Many local Boards of Health require notification and/or a record in the deed to the property if measured baseline sodium levels exceed 20 mg/L.
  • A US EPA Drinking Water Advisory recommends that sodium concentrations in drinking water not exceed 30 and 60 mg/L a threshold for taste-sensitive segments of the population.
  • New Hampshire DES has adopted a secondary, taste-related standard for sodium of 250 mg/L.
Common Sources

While sodium can occur naturally in the environment, sodium levels may be increased by road salt application and storage, fertilizers, industrial wastes, sewage and saltwater intrusion along coastal areas. Water softening treatment systems using sodium chloride salts can also significantly increase the sodium levels in the drinking water.

Taste & Odor

Concentrations of sodium greater than 200 mg/L can make drinking water taste salty, and at concentrations of 30-60 mg/L for taste-sensitive individuals.

Prevention/Treatment Considerations

If increased sodium levels are a result of water softening, substituting sodium-based salts with potassium-based salts should reduce the sodium concentration in the drinking water. Point-of-use reverse osmosis is also effective for reducing sodium.

NH DES New Hampshire has adopted 250 mg/L chloride and 250 mg/L sodium as state secondary standards.

Health and System Effects

High levels of sulfate (above 250 ppm) may have a laxative effect and cause dehydration, especially in infants. Sulfate minerals can cause scale buildup in water pipes, similar to other minerals. Sulfur-oxidizing bacteria produce effects similar to those of iron bacteria: they produce a dark slime that can clog plumbing and/or stain clothing.

Regulatory Guidelines – Health-Related

The US EPA Secondary Maximum Contaminant Level (non-enforceable guideline) for sulfate is 250 mg/L (based on a taste threshold). EPA has also established a health-based advisory value of 500 mg/L, a level at which adverse health effects could be experienced.

Common Sources

Sulfate most often enters drinking water when it comes in contact with underground rock formations and waste streams from nearby industrial activity.

Taste & Odor

High sulfates can produce a bitter or astringent taste and have a laxative effect.

Prevention/Treatment Considerations

Three types of treatment systems will remove sulfate from drinking water: reverse osmosis, distillation, or ion exchange. Water softeners, carbon filters, and sediment filters do not remove sulfate.

Total Dissolved Solids (TDS)
System Effects

Elevated TDS can result in incrustations, films, or precipitates on fixtures (e.g., scale formation or water spots on dishes); corrosion of fixtures, and reduced efficiency of hot water heaters, water filters and other equipment.

Regulatory Guidelines – Health-Related

The US EPA Secondary Maximum Contaminant Level (non-enforceable guideline) for Total Dissolved Solids is 500 mg/L. When TDS levels exceed 1,000 mg/L, water is generally considered unfit for human consumption.

Common Sources

Natural sources of TDS in drinking water include mineral springs, carbonate deposits, salt deposits, and sea water intrusion. Other sources can include industrial waste and sewage, urban run-off, fertilizers and pesticides used on lawns and farms, salts used for road de-icing, anti-skid materials, and more.

TDS is primarily comprised of mineral salts, some of which pose a variety of health hazards; the most problematic are nitrates, sodium, sulfates, barium, cadmium, copper and fluoride. A high level of TDS is an indicator of potential concerns, and warrants further investigation. Most often high levels of TDS are caused by the presence of potassium, chlorides and sodium. While these ions have little or no short-term effects, toxic ions (lead, arsenic, cadmium, nitrate and others) may also be dissolved in the water.

Taste & Odor

High TDS results in undesirable taste (e.g., bitter, salty or metallic taste).

Prevention/Treatment Considerations

Reverse osmosis and distillation are effective options for reducing high TDS.

Health Effects

Health effects from turbid water depends upon the type of material in the water that is causing the turbidity. Higher turbidity levels are often associated with disease-causing microorganisms such as viruses, parasites and some bacteria. These organisms can cause symptoms such as nausea, cramps, diarrhea, and headaches

Regulatory Guidelines – Health-Related

The US EPA Maximum Contaminant Level for water delivery systems using conventional filtration is 1.0 NTU; at no time can turbidity go above 5.0 NTU.

Common Sources

Turbidity is a measure of water clarity; turbid water can look cloudy or opaque and can also affect the color of the water.

Material that causes well water to become turbid includes: clay; silt; finely dissolved organic and inorganic material; microorganisms such as bacteria and viruses.

Turbid water can be caused by: treatment system residue (e.g., “dirty” salt in softener); leaky or malfunctioning septic or sewer system, soil erosion, algae or weeds, high iron concentrations which can give water a rust-red coloration, air bubbles or particles from a water treatment system.


Turbid water may appear cloudy or opaque.

Prevention/Treatment Considerations

Treatment of turbid water depends upon the type of contaminant causing the turbidity. Treatment options to remove turbidity include: chlorination (if determined to be caused by microorganisms), microfiltration, ozone treatment, distillation, aeration and Reverse Osmosis.

Health Effects

Uranium exposure can have toxic effects on human kidneys leading to kidney inflammation and changes in urine composition. Uranium can decay into other radioactive substances, such as radium, which can cause cancer with extensive exposures over a long enough period of time.

Regulatory Limit – Health-Related

The US EPA Maximum Contaminant Level (MCL) for uranium in drinking water is 30 µg/L (0.030 mg/L). When the uranium level is between 50%-100% of the MCL, we recommend conducting quarterly water quality monitoring (retesting) until the result is consistently below the MCL (in accordance with MassDEP requirements for public water supplies).

Common Sources

Uranium is a common, naturally-occurring radioactive substance. Uranium enters water by leaching from soil and rocks,

Prevention/Treatment Considerations

Uranium can be effectively removed from groundwater using strong base anion exchange and reverse osmosis.

Total Trihalomethanes (TTHM)
Health Effects

Chronic exposure to Total Trihalomethanes (TTHM) – bromodichloromethane, bromoform, chloroform and dibromochloromethane — is associated with effects on the heart, liver, kidney, and central nervous system damage, including increased risk of bladder and colorectal cancers. Pregnant women appear to be at the greatest risk, as some studies have linked THMs to reproductive problems, including miscarriage.

Regulatory Guidelines – Health-Related

The EPA Maximum Contaminant Level for the sum of the concentrations of the four TTHMs is 0.08 mg/L (80 ug/L). The Maximum Contaminant Level Goals (MCLG) for bromodichloromethane and bromoform have been set at zero/0 ug/L.

Common Sources

Total trihalomethanes are produced as a by-product of well/water system disinfection when chlorination products react with naturally-occurring organic and inorganic matter in the water. While drinking water containing THMs is an important exposure pathway, there is significant evidence that showering/bathing and other water uses, such as dishwashing and laundry, also pose exposure risks through inhalation.

Taste & Odor

Chloroform and bromoform are colorless and are reported to have a pleasant, non-irritating odor with a slightly sweet taste. Taste and odor information related to other trihalomethanes is unavailable.

Prevention/Treatment Considerations

TTHM can be removed from drinking water using activated carbon filters (faucet-mount or plumbed in; pitcher and dispenser filters are not effective for TTHM removal) or reverse osmosis.

2,4-Dichlorophenoxyacetic acid (2,4-D, Herbicide)
Health Effects

Based on studies performed in animals at high doses, 2,4-D can cause changes in the kidneys over months to years. Shorter-term studies showed thyroid, adrenal gland, and decreased body weight effects in developing animals at high doses. Other research has correlated 2,4-D exposure with cancer, endocrine disruption, reproductive effects, and neurotoxicity.

Regulatory Limits

The Maximum Contaminant Level Goals for 2,4-D and 2,4,5-TP in drinking water are 70 µg/L and 50 µg/L, respectively; no limit has been established for 2,4,5-T.

Common Sources

2,4-D (2,4-Dichlorophenoxyacetic acid), 2,4,5-TP (2,4,5-Trichlorophenoxypropionic acid) and 2,4,5-T (2,4,5-Trichlorophenoxyacetic acid) are part of the family of phenoxy herbicides, which are used for selective broad-leaf weed control in agricultural, lawn care and aquatic applications.

Treatment Considerations

Many pesticides (herbicides and insecticides) can be removed from drinking water by reverse osmosis or granulated activated carbon (GAC) filters.

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