Drinking Water Taste and Odor Active
“Nuisance” Constituents in Drinking Water
Does your drinking water taste, smell, or look unpleasant?
Some water is just unpleasant to drink—it’s cloudy, or it smells or tastes bad. Some drinking water discolors teeth or skin, stains laundry or plumbing fixtures, or corrodes or clogs pipes. These effects are caused when some naturally occurring constituents occur at concentrations high enough to be a nuisance, and are particularly common where groundwater is used as a drinking water supply.
Health concerns are not the only criteria that we use to judge our drinking water. In fact, often the most noticeable qualities that determine whether water is acceptable to consumers are unpleasant taste or odor, staining, poor reaction with soap, or mineral buildup in pipes and plumbing. These problems result from elevated concentrations of "nuisance" constituents.
Most nuisance constituents occur naturally. These constituents are more likely to occur at nuisance concentrations in groundwater than surface water, because they result from the reaction of groundwater with aquifer rocks and sediments as the water moves underground. Dissolved iron in groundwater can stain laundry, sinks, bathtubs, and toilets a brownish red, and can degrade plumbing and heating systems. Iron also gives drinking water an unpleasant taste, making it undrinkable for many well owners. Manganese often co-occurs with iron and causes many of the same problems. Hard water—defined by high concentrations of calcium and magnesium—causes water pipes and fixtures to become coated with scale, limits the ability of soaps and detergents to form suds, and can cause premature failure of plumbing and heating fixtures. pH outside of acceptable ranges can give water a metallic taste and can cause corrosion of pipes. A high dissolved solids concentration—a measure of all dissolved substances in water, also referred to as salinity—makes water taste disagreeably salty. Find a table that lists nuisance constituents and their noticeable effects at high concentrations here.
EPA Guidelines for Nuisance Constituents
The EPA recommends limits, called Secondary Maximum Contaminant Levels (SMCLs), for nuisance constituents in public water supplies. The SMCLs are non-health-based, non-enforceable guidelines for concentrations of 15 constituents in drinking water. These guidelines are designed to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color, and odor. These contaminants are not considered to present a risk to human health at the SMCL.
Because they can be smelled, tasted, or seen, nuisance constituents may be more likely to be noticed by consumers than contaminants that actually are a health risk. However, some constituents that have an SMCL also have a higher human-health benchmark. Manganese is one example—the black staining caused by manganese might be just a nuisance or might signal a concentration high enough to be a health risk. In other situations, the presence of nuisance constituents can signal geochemical conditions that promote high concentrations of other, more harmful contaminants. For example, high concentrations of dissolved solids are considered a nuisance because they cause water to taste salty, but high dissolved solids is not in itself a health concern. However, high dissolved solids can be an indication that there are elevated concentrations of arsenic, uranium, or other trace elements in the groundwater as well. The occurrence of nuisance constituents in drinking water therefore can indicate that testing for a broader range of constituents could be warranted to assess possible risks and to determine options for reducing those risks.
Nuisance Constituents in Groundwater Used for Drinking
Because the constituents considered to be a nuisance at high levels occur naturally in groundwater, it can be very common for drinking water from wells to have nuisance constituents. In a recent survey of 11 Principal Aquifers that supply most of the groundwater used in the U.S., groundwater contained at least one constituent at a concentration above its SMCL in 15 to 65 percent of the area studied in each aquifer. And in a survey from 1991 to 2010 of wells across the U.S. that tap the parts of aquifers used for drinking, at least one nuisance constituent exceeded its SMCL in more than half of the wells sampled. Nuisance constituents were particularly prevalent in the Glacial aquifer system (northern U.S.) and the Cambrian Ordovician aquifer system (north-central U.S.), where groundwater in more than 60 percent of each study area contained at least one nuisance constituent above its SMCL.
Many of the geochemical processes that affect groundwater quality occur over a long period of time as the groundwater slowly moves through the aquifer. The older the groundwater, the longer the water has been in contact with aquifer materials, and the greater the degree to which geochemical processes can change the pH, dissolved oxygen content, and concentration of dissolved solids, thereby increasing the potential for elevated concentrations of some nuisance constituents.
Even if an aquifer provides a plentiful supply of potable groundwater, nuisance constituents can prevent many consumers from using it for drinking. Some consumers choose to buy bottled water rather than drink tap water, at a cost of hundreds of dollars each year. Water-treatment systems can remove nuisance constituents from groundwater but can be costly to install and maintain.
Follow the links below to learn more about topics related to taste and odor of drinking water.
Groundwater Quality—Current Conditions and Changes Through Time
Access datasets associated with constituents causing taste and odor issues in drinking water.
Follow the links below to access publications that discuss nuisance contaminants that affect taste and odor in drinking water and related topics.
Large decadal-scale changes in uranium and bicarbonate in groundwater of the irrigated western U.S
Potential corrosivity of untreated groundwater in the United States
Predicting arsenic in drinking water wells of the Central Valley, California
Groundwater quality in the Southeastern Coastal Plain aquifer system, southeastern United States
Groundwater quality in the Northern Atlantic Coastal Plain aquifer system, eastern United States
Groundwater quality in the Basin and Range Basin-Fill Aquifers, southwestern United States
Groundwater quality in the Valley and Ridge and Piedmont and Blue Ridge carbonate-rock aquifers, eastern United States
Groundwater quality in the Coastal Lowlands aquifer system, south-central United States
The quality of our Nation's waters: water quality in the Mississippi embayment-Texas coastal uplands aquifer system and Mississippi River Valley alluvial aquifer, south-central United States, 1994-2008
The quality of our Nation's waters: Water quality in principal aquifers of the United States, 1991-2010
The quality of our Nation's waters: water quality in the glacial aquifer system, northern United States, 1993-2009
The quality of our Nation's waters: water quality in the Northern Atlantic Coastal Plain surficial aquifer system, Delaware, Maryland, New Jersey, New York, North Carolina, and Virginia, 1988-2009
The quality of our nation's waters: water quality in the Principal Aquifers of the Piedmont, Blue Ridge, and Valley and Ridge regions, eastern United States, 1993-2009
Access datasets associated with constituents causing taste and odor issues in drinking water.
- Overview
Some water is just unpleasant to drink—it’s cloudy, or it smells or tastes bad. Some drinking water discolors teeth or skin, stains laundry or plumbing fixtures, or corrodes or clogs pipes. These effects are caused when some naturally occurring constituents occur at concentrations high enough to be a nuisance, and are particularly common where groundwater is used as a drinking water supply.
Health concerns are not the only criteria that we use to judge our drinking water. In fact, often the most noticeable qualities that determine whether water is acceptable to consumers are unpleasant taste or odor, staining, poor reaction with soap, or mineral buildup in pipes and plumbing. These problems result from elevated concentrations of "nuisance" constituents.
Most nuisance constituents occur naturally. These constituents are more likely to occur at nuisance concentrations in groundwater than surface water, because they result from the reaction of groundwater with aquifer rocks and sediments as the water moves underground. Dissolved iron in groundwater can stain laundry, sinks, bathtubs, and toilets a brownish red, and can degrade plumbing and heating systems. Iron also gives drinking water an unpleasant taste, making it undrinkable for many well owners. Manganese often co-occurs with iron and causes many of the same problems. Hard water—defined by high concentrations of calcium and magnesium—causes water pipes and fixtures to become coated with scale, limits the ability of soaps and detergents to form suds, and can cause premature failure of plumbing and heating fixtures. pH outside of acceptable ranges can give water a metallic taste and can cause corrosion of pipes. A high dissolved solids concentration—a measure of all dissolved substances in water, also referred to as salinity—makes water taste disagreeably salty. Find a table that lists nuisance constituents and their noticeable effects at high concentrations here.
EPA Guidelines for Nuisance Constituents
The EPA recommends limits, called Secondary Maximum Contaminant Levels (SMCLs), for nuisance constituents in public water supplies. The SMCLs are non-health-based, non-enforceable guidelines for concentrations of 15 constituents in drinking water. These guidelines are designed to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color, and odor. These contaminants are not considered to present a risk to human health at the SMCL.Because they can be smelled, tasted, or seen, nuisance constituents may be more likely to be noticed by consumers than contaminants that actually are a health risk. However, some constituents that have an SMCL also have a higher human-health benchmark. Manganese is one example—the black staining caused by manganese might be just a nuisance or might signal a concentration high enough to be a health risk. In other situations, the presence of nuisance constituents can signal geochemical conditions that promote high concentrations of other, more harmful contaminants. For example, high concentrations of dissolved solids are considered a nuisance because they cause water to taste salty, but high dissolved solids is not in itself a health concern. However, high dissolved solids can be an indication that there are elevated concentrations of arsenic, uranium, or other trace elements in the groundwater as well. The occurrence of nuisance constituents in drinking water therefore can indicate that testing for a broader range of constituents could be warranted to assess possible risks and to determine options for reducing those risks.
Nuisance Constituents in Groundwater Used for Drinking
Because the constituents considered to be a nuisance at high levels occur naturally in groundwater, it can be very common for drinking water from wells to have nuisance constituents. In a recent survey of 11 Principal Aquifers that supply most of the groundwater used in the U.S., groundwater contained at least one constituent at a concentration above its SMCL in 15 to 65 percent of the area studied in each aquifer. And in a survey from 1991 to 2010 of wells across the U.S. that tap the parts of aquifers used for drinking, at least one nuisance constituent exceeded its SMCL in more than half of the wells sampled. Nuisance constituents were particularly prevalent in the Glacial aquifer system (northern U.S.) and the Cambrian Ordovician aquifer system (north-central U.S.), where groundwater in more than 60 percent of each study area contained at least one nuisance constituent above its SMCL.Many of the geochemical processes that affect groundwater quality occur over a long period of time as the groundwater slowly moves through the aquifer. The older the groundwater, the longer the water has been in contact with aquifer materials, and the greater the degree to which geochemical processes can change the pH, dissolved oxygen content, and concentration of dissolved solids, thereby increasing the potential for elevated concentrations of some nuisance constituents.
Even if an aquifer provides a plentiful supply of potable groundwater, nuisance constituents can prevent many consumers from using it for drinking. Some consumers choose to buy bottled water rather than drink tap water, at a cost of hundreds of dollars each year. Water-treatment systems can remove nuisance constituents from groundwater but can be costly to install and maintain.
- Science
Follow the links below to learn more about topics related to taste and odor of drinking water.
Groundwater Quality—Current Conditions and Changes Through Time
Is groundwater the source of your drinking water? The USGS is assessing the quality of groundwater used for public supply using newly collected data along with existing water-quality data. Learn more about this invisible, vital resource so many of us depend on. - Data
Access datasets associated with constituents causing taste and odor issues in drinking water.
- Publications
Follow the links below to access publications that discuss nuisance contaminants that affect taste and odor in drinking water and related topics.
Large decadal-scale changes in uranium and bicarbonate in groundwater of the irrigated western U.S
Samples collected about one decade apart from 1105 wells from across the U.S. were compiled to assess whether uranium concentrations in the arid climate are linked to changing bicarbonate concentrations in the irrigated western U.S. Uranium concentrations in groundwater were high in the arid climate in the western U.S, where uranium sources are abundant. Sixty-four wells (6%) were above the U.S. EAuthorsKaren R. Burow, Kenneth Belitz, Neil M. Dubrovsky, Bryant C. JurgensFilter Total Items: 29Potential corrosivity of untreated groundwater in the United States
Corrosive groundwater, if untreated, can dissolve lead and other metals from pipes and other components in water distribution systems. Two indicators of potential corrosivity—the Langelier Saturation Index (LSI) and the Potential to Promote Galvanic Corrosion (PPGC)—were used to identify which areas in the United States might be more susceptible to elevated concentrations of metals in household drAuthorsKenneth Belitz, Bryant C. Jurgens, Tyler D. JohnsonPredicting arsenic in drinking water wells of the Central Valley, California
Probabilities of arsenic in groundwater at depths used for domestic and public supply in the Central Valley of California are predicted using weak-learner ensemble models (boosted regression trees, BRT) and more traditional linear models (logistic regression, LR). Both methods captured major processes that affect arsenic concentrations, such as the chemical evolution of groundwater, redox differenAuthorsJoseph D. Ayotte, Bernard T. Nolan, JoAnn M. GronbergGroundwater quality in the Southeastern Coastal Plain aquifer system, southeastern United States
Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Southeastern Coastal Plain aquifer system constitutes one of the important areas being evaluated. One or more inorganAuthorsJeannie Barlow, Bruce D. Lindsey, Kenneth BelitzGroundwater quality in the Northern Atlantic Coastal Plain aquifer system, eastern United States
Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Northern Atlantic Coastal Plain aquifer system constitutes one of the important areas being evaluated. One or more inAuthorsBruce D. Lindsey, Kenneth BelitzGroundwater quality in the Basin and Range Basin-Fill Aquifers, southwestern United States
Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Basin and Range basin-fill aquifers constitute one of the important areas being evaluated. One or more inorganic consAuthorsMaryLynn Musgrove, Kenneth BelitzGroundwater quality in the Valley and Ridge and Piedmont and Blue Ridge carbonate-rock aquifers, eastern United States
Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Valley and Ridge and Piedmont and Blue Ridge carbonate-rock aquifers constitute two of the important areas being evalAuthorsBruce D. Lindsey, Kenneth BelitzGroundwater quality in the Coastal Lowlands aquifer system, south-central United States
Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Coastal Lowlands aquifer system constitutes one of the important areas being evaluated. One or more inorganic constitAuthorsJeannie R.B. Barlow, Kenneth BelitzThe quality of our Nation's waters: water quality in the Mississippi embayment-Texas coastal uplands aquifer system and Mississippi River Valley alluvial aquifer, south-central United States, 1994-2008
About 8 million people rely on groundwater from the Mississippi embayment—Texas coastal uplands aquifer system for drinking water. The Mississippi River Valley alluvial aquifer also provides drinking water for domestic use in rural areas but is of primary importance to the region as a source of water for irrigation. Irrigation withdrawals from this aquifer are among the largest in the Nation and pAuthorsJames A. Kingsbury, Jeannie R. B. Barlow, Brian G. Katz, Heather L. Welch, Roland W. Tollett, Lynne S. FahlquistThe quality of our Nation's waters: Water quality in principal aquifers of the United States, 1991-2010
About 130 million people in the United States rely on groundwater for drinking water, and the need for high-quality drinking-water supplies becomes more urgent as our population grows. Although groundwater is a safe, reliable source of drinking water for millions of people nationwide, high concentrations of some chemical constituents can pose potential human-health concerns. Some of these contaminAuthorsLeslie A. DeSimone, Peter B. McMahon, Michael R. RosenThe quality of our Nation's waters: water quality in the glacial aquifer system, northern United States, 1993-2009
The glacial aquifer system underlies much of the northern United States. About one-sixth (41 million people) of the United States population relies on the glacial aquifer system for drinking water. The primary importance of the glacial aquifer system is as a source of water for public supply to the population centers in the region, but the aquifer system also provides drinking water for domestic uAuthorsKelly L. Warner, Joseph D. AyotteThe quality of our Nation's waters: water quality in the Northern Atlantic Coastal Plain surficial aquifer system, Delaware, Maryland, New Jersey, New York, North Carolina, and Virginia, 1988-2009
The surficial aquifer system of the Northern Atlantic Coastal Plain is made up of unconfined aquifers that underlie most of the area. This aquifer system is a critical renewable source of drinking water and is the source of most flow to streams and of recharge to underlying confined aquifers. Millions of people rely on the surficial aquifer system for public and domestic water supply, in particulaAuthorsJudith M. Denver, Scott W. Ator, Jeffrey M. Fischer, Douglas C. Harned, Christopher Schubert, Zoltan SzaboThe quality of our nation's waters: water quality in the Principal Aquifers of the Piedmont, Blue Ridge, and Valley and Ridge regions, eastern United States, 1993-2009
The aquifers of the Piedmont, Blue Ridge, and Valley and Ridge regions underlie an area with a population of more than 40 million people in 10 states. The suburban and rural population is large, growing rapidly, and increasingly dependent on groundwater as a source of supply, with more than 550 million gallons per day withdrawn from domestic wells for household use. Water from some of these aquifeAuthorsBruce D. Lindsey, Tammy M. Zimmerman, Melinda J. Chapman, Charles A. Cravotta, Zoltan Szabo - Web Tools
Access datasets associated with constituents causing taste and odor issues in drinking water.