Health-related (primary drinking water) contaminants that consumers should be aware of are microbiological contamination, total coliform bacteria, Giardia lamblia and Cryptosporidium parvum

protozoa, nitrate, radon, lead, synthetic organic chemicals (SOCs), VOCs and pesticides.

Microbiological Contamination

Microbiological contamination is normally a problem with private domestic wells which do not receive the disinfection that a public drinking water source does. The source of microbiological contamination in groundwater can be from on-lot sewage (septic) systems or agricultural runoff. Improper well onstruction and poor location of the well can result in microbiological contamination.

The presence of coliform bacteria in drinking water is easy for a certified laboratory to detect and can be used to assess the likelihood that other microbiological contaminants are present.

Individuals should have their well water tested for bacteria at least annually.

Total Coliform Bacteria

The total coliform bacteria test is used to determine if bacterial contamination is present. Although most coliform bacteria do not cause illness, the total coliform test is easy and inexpensive, and is used as an indicator for the possible presence of other disease-causing microorganisms in the water. If coliform bacteria are in your water, then bacteria and viruses that can make you sick may also be contaminating your supply. The acceptable level is for no coliform bacteria to be present.

However, a test report for an uncontaminated sample may read coliform negative, less than one (<1) per 100 mL, or less than 2.2 (<2.2) per 100 mL, depending on the measurement and reporting technique used by the individual laboratory. Ultraviolet disinfection treatment devices can provide water that is safe from microbiological contamination. Chlorination is also an effective means of disinfection, and is normally used when problems such as high iron or hydrogen sulfide also are present.

Giardia and Cryptosporidium

Giardiasis is a waterborne disease caused by the protozoan Giardia lamblia that lives in the small intestine of warmblooded mammals. Similarly, cryptosporidiosis is caused by Cryptosporidium parvum. Infection results from drinking water from a surface or surface water influenced source contaminated by Giardia cysts. Giardia normally is not a problem with groundwater sources, unless they are under the direct influence of surface water. Public water systems that test positive for Giardia cysts are required to immediately notify consumers of the problem.

Mechanical filtration is the most cost-effective way to remove Giardia cysts, although reverse osmosis and distillation also will work.

Nitrate

Nitrate is a fairly common drinking water contaminant, usually associated with wells and springs in agricultural areas. Public water supplies routinely must test for nitrate and remove it if it exceeds drinking water limits, but many private wells may contain high levels of nitrate without the owners being aware of it. High nitrate levels usually result from agricultural activities or on-lot sewage systems.

Chemical fertilizers and manure are rich sources of nitrogen compounds, which are converted to nitrate in the soil. People, particularly those with young children, living in farming areas who obtain their water from individual wells, springs or surface sources should have their water tested regularly for nitrate.

At high concentrations, nitrate can cause methemoglobinemia, commonly called blue baby syndrome, in infants. Infants less than three months old are at greatest risk from the illness, which deprives vital organs of oxygen. This disease, although uncommon, can occur when high concentrations of nitrate are in the drinking water. For public drinking water supplies, the maximum contaminant level for nitrate is 10 mg/L expressed as nitrogen (N) or 45.0 mg/L expressed as nitrate (NO3). Nitrate levels can change drastically based on rainfall, fertilizer application and geology. Reverse osmosis, ion exchange and distillation treatment devices are effective for removal of nitrates.

Radon

Radon is a naturally occurring radioactive gas that is found in varying concentrations in most soils and rock. Radon gas can cause lung cancer. Normally, most radon that accumulates in the home seeps from the soil into the home through cracks and holes in the foundation. However, in some cases, household water can be the primary or a contributing source. In these cases, radon is emitted into the home from water used for showering, cooking and washing.

It is only a problem where groundwater is used to supply drinking water. The danger primarily is from the inhalation of radioactive gas given off, rather than consumption of the water.

To find out if you have a problem with radon in your home, have the air tested first. If the air level is less than 4 picocuries per liter (pCi/L), there usually is no need to have the water tested. If the air level in non-basement areas is above 4 pCi/L, then the water should be tested to determine if it is the primary or a major contributing source. A level of 10,000 pCi/L, in the water will increase indoor air levels by about 1 pCi/L.

Since radon levels in the air can vary substantially from day to day, it is a good idea to have at least two air samples taken with the samples spaced over several days in a closed house.

If radon levels in the water are excessive, ventilating the kitchen, laundry and bathrooms may reduce the radon concentrations in the home to an acceptable level. If additional tests show excessive levels, some type of water treatment should be considered. Two types of devices that work very well in removing radon are activated carbon and aeration treatment devices.

Entry-device treatment devices should be used where radon is a problem. Because radon decays rapidly, radioactivity will not build up in the treatment devices, unless radon concentrations are exceptionally high in the raw water. If radon levels are high, lead-210, a radon decay product can build up in the carbon filter and give off harmful radioactivity. Where high radon concentrations are measured, it is advisable to shield the unit, or place the unit outside the home or in an isolated area of the basement.

Lead

Lead from pipes and solder can dissolve into drinking water as the water flows through plumbing systems. In most cases, lead in drinking water comes from the household plumbing, not from the water source or the public water system. The highest lead concentrations are found in homes with lead service lines or lead plumbing. Lead commonly was used for service lines, the line connecting the home to the water main, in homes built up to the early 1950s.

Most public water suppliers maintain records of what type of pipe was used for service lines.

High lead concentrations also can be found in homes with copper piping where lead solder was used for joining pipes. Copper is the most popular type of residential piping and is found in most homes. High lead concentrations can be found in newer homes where lead solder was used.

Brass and bronze in faucets and other plumbing fixtures often contain lead and may be a considerable source of lead in the drinking water of homes with brass or bronze faucets or fixtures.

Drinking water is only one possible source of lead to the human body. Other sources include paint chips, air, soil, food and dust. Infants, young children and pregnant women are at greatest risk from lead exposure. The effects of lead on children include increased hyperactivity, decreased intelligence levels, learning deficiencies and kidney disorders.

Since you cannot see, taste, or smell lead, the only way to tell if you have a lead problem in your drinking water is by having your water tested. If tests show that the level in household water is in the area of 0.015 mg/L or higher, it is advisable, especially if there are pregnant women or young children in the home, to consider treatment to reduce the lead level in your tap water, use permitted bottled water, or use a flushing program to reduce the lead levels in the water that is consumed.

As water sits in the household plumbing or service line, lead can be leached from old lead pipes, lead soldered joints, or brass or bronze plumbing fixtures. Water that has a lower alkalinity or pH is more corrosive and will leach more lead into the water. The longer the water lays unused in the pipes, the greater the potential for increased amounts of lead in the water. In homes where plumbing work recently has been done, home owners should check the screen in the faucet aerator and remove any loose particles of solder. Lead concentrations can be reduced by allowing the water to run at the faucet after periods of nonuse. Anytime the water in a particular faucet has not been used for six hours or longer, the water should be run until a noticeable change in temperature can be felt. The flushing will clear out the water which has been sitting dormant in the pipes and should substantially reduce the lead concentration in the water where the plumbing system is the source of the contamination. After flushing, water can be stored for later use for drinking and cooking.

The other way to reduce lead concentrations is to use point-of-use treatment devices. Several types of treatment devices can work quite well to remove lead including reverse osmosis, activated alumina, some activated carbon absorption filters with designs such as precoat or carbon block, and distillation. If your drinking water exceeds the drinking water action level for lead of 0.015 mg/L, purchasing a device that will insure that the device has been tested and is effective for lead removal. Be sure to maintain the system as recommended by the manufacturer. If lead is the only contaminant, an activated alumina filter can be used to reduce lead concentrations. If lead is only one of several contaminants, then an activated carbon filter validated as effective for lead reduction or a more expensive reverse osmosis system, both of which can remove a greater number of contaminants, may be needed.

Synthetic Organic Chemicals (SOCs)

The term synthetic organic chemicals refers to all manmade organic chemicals, of which thousands are known to exist. There are many SOCs, and their applications vary from such uses as heat exchangers (polychlorinated biphenyls or PCBs) to fuel oils (kerosene).

Common synthetic organic chemicals include dioxin, lindane, chlordane and endrin.

Technically, both pesticides and volatile organic chemicals are all SOCs. Due to their unique characteristics, pesticides and volatile organic chemicals typically are placed in separate categories.

Pesticides. Pesticides are a broad class of compounds that include herbicides, insecticides and rodenticides. Pesticides can enter a drinking water supply from direct application for the control of vegetation or insects and from non-point sources such as runoff from agricultural, urban and suburban areas.

The majority of health effects data that has been accumulated has been based upon exposure to relatively high concentrations resulting from spraying operations or industrial accidents. Activated carbon filters are effective for the removal of pesticides.

If you believe that pesticides may have contaminated your drinking water, several sources can provide you with additional information. Laboratories also can be of assistance in determining what to test for if you are unsure of what pesticides may have been used.

Volatile Synthetic Organic Chemicals (VOCs)

Volatile synthetic organic chemicals are man-made substances that have been responsible for the contamination of both surface and groundwater supplies.

VOCs have a wide variety of uses in many types of industrial, commercial, agricultural and household activities. VOCs may also form from the natural breakdown of SOCs in the environment.

Public water suppliers must meet stringent requirements for VOCs. However, some private wells or springs may contain VOC levels that are cause for concern. You are far less likely to find VOCs in your water than bacteria or nitrate. VOC contamination has been found near petroleum refineries, chemical plants, manufacturing plants, landfills, leaking underground storage tanks and as the result of careless storage or disposal around the home. If you live near one of these types of facilities or are concerned about possible contamination, you should have your water tested for VOCs. Many VOCs will not be detectable by the taste or odor of the water.

VOCs can be removed from water by boiling the water in a well ventilated area for 10 to 15 minutes, by aeration treatment devices, or by filtering the water through activated carbon treatment units.

Chlorination of water that is high in naturally occurring organic compounds can produce small amounts of trihalomethanes or THMs (chloroform, bromodichloromethane, dibromochloromethane and bromoform). The drinking water standard that public water systems are required to maintain for total trihalomethanes is 0.08 mg/L (80 ppb). Long-term exposure to levels above this standard may contribute to a small additional cancer risk. Despite these risks, however, the disease prevention benefits of chlorination still outweigh the small negative effects of trihalomethanes. Activated carbon filters are commonly used to reduce SOCs.