Why test my drinking water?

What is it?

Coliforms are a group of common bacteria found in soil, water, and the gut and fecal waste of humans and other warm-blooded animals. It is common practice to report total coliform results as "presence" or "absence" rather than an exact concentration as their mere presence is enough to trigger further testing or corrective action. Presence of coliform bacteria is used as an indicator to identify when water is contaminated with human or animal waste. The presence of fecal coliforms indicates inadequate water treatment or a problem with the local water distribution system. While most coliform bacteria are harmless, some strains cause illness.

What is it?

Escherichia coli (E. coli) are the most common type of fecal coliform bacteria. E. coli in water is an indicator of human and animal waste contamination. It is common practice to report E. coli results as "presence" or "absence" rather than an exact concentration as their mere presence is enough to trigger corrective action. The presence of E. coli in tap water can indicate inadequate water treatment or a problem with the local water distribution system. Although most strains of E. coli are harmless, some may cause severe illness. If E. coli is detected in tap water, the water should not be used for drinking until properly disinfected.

What is it?

Arsenic is a naturally occurring element that has elemental, organic, and inorganic forms. The two forms of arsenic commonly found in drinking water that present a health risk are inorganic: arsenic III, or arsenite, and arsenic V, or arsenate. Inorganic forms of arsenic are considered highly toxic while most organic forms are considered to be essentially non-toxic. Certain organic arsenic compounds, including various methyl and phenyl derivatives, may pose a toxicity risk. Inorganic arsenic was previously used in the production of copper chromated arsenate, a wood preservative, while organic forms were primarily used as pesticides. Safer alternatives have now mostly replaced arsenic in these applications, but arsenic is persistent in the environment so past contamination sources remain relevant. Organic arsenic was also previously used as an additive in animal feed before the FDA withdrew approval for arsenic-based animal drugs. Elemental arsenic is primarily used in the production of arsenic alloys, which are often used in lead-acid batteries, as well as in semiconductors and light-emitting diodes. These are the primary applications of arsenic in the current day. Arsenic has been found in surface water, groundwater, and drinking water throughout the US, though higher levels of arsenic tend to be found in groundwater sources than in surface water.

What is it?

Uranium is a weakly radioactive heavy metal found naturally in bedrock and used in nuclear weapons, some ceramics, electron microscopy, photography, and certain fertilizers. Uranium is weakly radioactive because all of its isotopes (Uranium-234, Uranium-235, and Uranium-238) are unstable. Ninety-nine percent of naturally existing uranium is in the isotope form uranium-238. The EPA has established a maximum contaminant level for uranium in drinking water in response to human and animal studies indicating kidney toxicity.

What is it?

Total hardness is the sum of all dissolved, multivalent metals in your water. While hardness primarily measures the levels of calcium and magnesium in your water, other ions like aluminum, copper, barium, iron, manganese, strontium, and zinc also contribute to total hardness. Water that has high hardness, described as 'hard water', contains high concentrations of naturally occurring dissolved minerals. Total hardness is composed of temporary and permanent hardnesses. Temporary, or carbonate, hardness can be removed from water by boiling and is responsible for the scaling caused by hard water as it reacts with heat. Permanent, or noncarbonate, hardness cannot be removed by boiling water. The hardness of water indicates the degree to which the water reacts with soap; hard water requires more soap to produce a lather and often deposits precipitates, or 'soap scum'. Hardness is usually reported in units of calcium carbonate equivalency, but grains per gallon is a common alternative unit.

What is it?

Lead is a naturally occuring heavy metal commonly found in tap water. While lead is now a regulated substance, it was widely used in the past in many household products including gasoline, paint, pipes, and plumbing materials. Corrosion of plumbing is the largest source of lead in drinking water. Homes built before 1986 are more likely to have lead plumbing, and an estimated 6 to 10 million lead service lines are still in use by homes throughout the United States. Even low levels of lead exposure can result in significant health impacts, especially developmental effects on children exposed to lead through dust, soil or water.

What is it?

Alkalinity is a key measure of a water sample's general chemistry. Alkalinity measures the capacity of water to neutralize acids. Alkalinity is thus indicative of the stability of a water sample's pH upon the addition of acid; water with higher alkalinity will maintain a stable pH after the addition of more acid. Water with low alkalinity cannot buffer against such changes and can therefore become acidic and potentially corrosive to plumbing.The vast majority of alkalinity comes from dissolved carbonate and bicarbonate, though other compounds, like phosphates and borates, contribute minorly to alkalinity.

What is it?

Iron is an abundant metal in the environment that exists in three states in water: ferrous ("clear water iron"), ferric ("red water iron"), and organic iron. It is commonly found in tap water and is known for its reddish-yellow discoloration of water and staining. While iron in drinking water is not typically considered harmful to human health, the presence of iron can lead to or indicate other hazards, such as pipe corrosion.

What is it?

Total heterotrophic plate count (HPC) is a measure of the colonies of heterotrophic bacteria, or bacteria that require organic carbon for growth, in drinking water. HPC tests have historically been used to indicate water safety, but as more specific tests have been developed, HPC is more commonly used to assess the effectiveness of treatment processes. Bacteria that do not get eliminated during water disinfection can regrow depending on the water's temperature, flow conditions, nutrient availability, and lack of residual disinfectant. Many HPC bacteria are non-hazardous, so total HPC alone does not directly indicate health risk. Abrupt increases in HPC levels may indicate fecal contamination.

What is it?

Gross alpha activity measures the total amount of radioactivity in a water sample emitted by decaying alpha-emitting elements, notably radioactive isotopes of uranium, radium, and radon. Alpha emitters are used to treat cancer, as an eliminator of static in paper mills and in other products like smoke detectors. Radioactive atoms release high energy alpha particles that pull electrons off of the atoms in cells. This process is called ionizing radiation, and may lead to harmful changes in cells and tissues. The toxicity of an alpha emitter depends on the amount of energy it releases and how organ systems respond to that energy. Exposure to elevated gross alpha activity is associated with increased cancer risk and genotoxicity, but toxicity to individual systems is dependent on the type of alpha emitter present.

What is it?

Gross beta activity measures the total amount of radioactivity in a water sample emitted by decaying beta-emitting elements, notably radioactive isotopes of potassium, radium, lead, and strontium. Any water that contains potassium will have a small amount of the beta-emitting isotope potassium-40, which will contribute to the water's gross beta activity. Beta emitters are used in cancer treatments and scans as well as emergency phosphorescent lighting. Radioactive atoms release high energy beta particles that pull electrons off of the atoms in cells. This process is called ionizing radiation, and may lead to harmful changes in cells and tissues. The toxicity of a beta emitter depends on the amount of energy it releases and how organ systems respond to that energy. Exposure to elevated gross beta activity is associated with increased cancer risk and genotoxicity, but toxicity to individual systems is dependent on the type of beta emitter present. Gross beta activity in drinking water is regulated in a slightly more complicated manner than is typical for other contaminants. Gross beta is measured by laboratories in units of pCi/L, the contribution of potassium-40 is subtracted, and if that total exceeds 50 pCi/L the individual ions contributing to the beta radiation are determined. The contributions of individual ions are determined in exposure units of mrem/yr and compared with the MCL of 4 mrem/yr. We do not display the MCL on our reports due to the more complex process entailed in regulating gross beta activity.

What is it?

Fluoride is a naturally occuring mineral in the environment and an essential element of tooth enamel. Public health agencies endorse adding fluoride to drinking water–a process called fluoridation–as an effective method of protecting against dental decay, especially in children. High levels of fluoride exposure, common in groundwater around the world, can result in debilitating dental and skeletal fluorosis. Such elevated concentrations are not found in adequately managed water systems.

What is it?

Nitrates are inorganic nonmetal compounds that form naturally when nitrogen combines with oxygen or ozone. Nitrates have many uses from fertilizers to food preservatives. In drinking water, nitrate may be an indicator of nearby agricultural or septic tank contamination. Excessive levels of nitrate in drinking can pose a particular health risk to infants.

What is it?

Copper is a naturally occuring metal that is widely used in plumbing, faucets, and fixtures. Copper enters drinking water primarily via corrosion of copper plumbing. While copper is an essential element for human health, ingesting too much copper can have harmful effects, especially for children.

What is it?

Chromium is a naturally occurring element that is widely used in manufacturing processes to make metal alloys such as stainless steel. Chromium is also present in some consumer products. Of the two most common forms of chromium—chromium (III) and (VI)—chromium (VI) is the more toxic form. Hexavalent chromium (VI) is associated with adverse gastrointestinal and hematological effects when ingested. Trivalent chromium (III), on the other hand, is an essential nutrient for human health in small amounts. EPA regulates both hexavalent and trivalent chromium, but standards are set assuming that a measurement of total chromium is 100 percent chromium (VI) to ensure that standards are most health protective.

What is it?

Haloacetic acids (HAAs) are a group of contaminants that are primarily formed as byproducts when chlorine, used as a disinfectant to kill harmful microorganisms, reacts with organic matter. HAA formation is dependent on a variety of factors in water, including the amount and type of organic matter present, temperature, pH, and chlorine dose. They are also produced for use in chemical synthesis, pesticides, medicines, and preservatives. Nine HAAs have been identified in drinking water, and five are federally regulated, including monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid. Elevated levels of HAAs in drinking water are associated with increased cancer risk.

What is it?

THMs (trihalomethanes) are a group of contaminants that form in drinking water systems when a disinfectant, typically chlorine, reacts with organic matter. Total THMs measures the total levels of four federally regulated THMs: chloroform, bromoform, bromodichloromethane, and dibromochloromethane. THM formation is dependent on a variety of factors in water, including the amount and type of organic matter, temperature, pH, salinity, and disinfectant used. In addition to their inadvertent creation during water disinfection and from natural sources, THMs are produced for use in the manufacture of refrigerants, other organic chemicals, gauge fluids, pesticides, and propellants. THMs are readily volatile, thus all routes of exposure (ingestion, inhalation and dermal) are relevant if one is exposed via drinking water. Health effects of total THMs in drinking water include liver and kidney toxicity, as well as increased risk of cancer.

What is it?

Manganese is a transition metal commonly found at low levels in soil, air, and water and in food as an essential nutrient. It has many uses as an industrial alloy (e.g. steel) and an oxidizing agent in rubber, glass, ceramic, and fertilizer/fungicide production. The presence of manganese in water may cause discoloration of water and dark brown or black stains on plumbing fixtures. While manganese is an essential nutrient at low doses, chronic exposure to high concentrations of manganese may have harmful impacts on the nervous system, especially for young children.