Warning: mysql_result(): Unable to jump to row 0 on MySQL result index 6 in /www/ext/pubs/html/stdheader.php on line 53
Warning: mysql_result(): Unable to jump to row 0 on MySQL result index 6 in /www/ext/pubs/html/stdheader.php on line 54
Warning: mysql_result(): Unable to jump to row 0 on MySQL result index 6 in /www/ext/pubs/html/stdheader.php on line 55
Warning: mysql_result(): Unable to jump to row 0 on MySQL result index 6 in /www/ext/pubs/html/stdheader.php on line 56
Warning: mysql_result(): Unable to jump to row 0 on MySQL result index 6 in /www/ext/pubs/html/stdheader.php on line 57
Your Drinking Water: Lead
Dale Dorman, MSExtension Housing & Environment Specialist
Individuals are exposed to lead from a variety of sources, but the elevated lead levels in some drinking water in the United States are a new public concern. Because of this concern, the U.S. Environmental Protection Agency (EPA) recently established a new National Primary Drinking Water regulation for lead, reducing the acceptable lead level from 50 parts per billion to 15 parts ppb. The EPA requires public water suppliers to test water and when high lead levels are found, to conduct public education programs and treat the water to bring it within safe limits. Private water suppliers, including wells, are not regulated by EPA. The owner must test and treat the water as needed to avoid health risks.
Lead does not have any beneficial effect on humans or animals. Rather, it reacts with the enzymes within the body to slow or stop essential physiological reactions. Chronic exposure to low levels of lead (less than 1 mg) over an extended period of time can have severe effects. Too much lead in the body can cause serious damage to the brain, kidneys, nervous system and red blood cells. Those at the greatest risk, even with short term exposure, are young children and pregnant woman.
According to the EPA, lead dosage that would have little effect on an adult can have a much greater effect on a small child. Growing children absorb lead more rapidly than adults do because of their body weight and metabolic differences. A child's mental and physical development can be irreversibly stunted by over-exposure to lead. Lead in drinking water can also be a problem for infants whose diet consists of liquids--such as baby formula made with water.
The natural lead content of surface and groundwater is negligible in Georgia. Most of the lead in household water comes from the plumbing in the house, not from the local water supply. Corrosive water (soft, acidic, or low pH) can dissolve lead from the supply pipes, faucets, or, solder and flux, used to connect copper pipes. Some brass components such as pump impellers and faucets also contain lead which can corrode and contaminate water.
Lead-contaminated drinking water occurs most frequently in recently constructed or very old homes. Many homes built from the early 1900s to about 1940 used lead pipes for interior plumbing. Lead piping was also used for many service connections that join homes to public water supplies. In 1986 a nationwide ban restricted the use of lead pipes for drinking water supplies.
When copper pipes replaced lead pipes, lead solder and flux were often used to join the pipes. Lead solder may be the major cause of lead contamination in drinking water today. In Georgia, the use of lead solder was banned in 1986, however, illegal use does continue. Since 1988, solder that has a lead content over 0.2 percent must be labeled to say that it cannot be used for joints or fittings in any private or public drinking water system.
Newer homes having copper pipes and solder may also be at risk of lead contamination. Mineral deposits build up in the pipes if the water is not too corrosive and the coating insulates the water from the solder. However, it may take five years or longer for the coating to form. Until then, the water is in direct contact with the lead. Household faucets may be another source of contamination. Chrome-plated faucets are generally made of brass, which contains 3 to 8 percent lead. Homes with plastic drinking water lines should not have problems with lead contamination from pipes, because fittings are glued together rather soldered.
Testing is the only way to know the level of lead in your drinking water. Analysis of water samples should be done by a state-certified laboratory using EPA-approved methods. Some cities and counties will conduct a lead test for free or a small charge.
Private testing laboratories are listed in the yellow pages of the telephone book. their fees range from $25 to $75.
The University of Georgia Cooperative Service will conduct a water test for lead for a $5 fee. Contact your local Cooperative Extension agent for information.
Before collecting water for testing, contact the laboratory or agency that will conduct the test for information concerning the procedure for testing. A two-sample procedure is needed to evaluate the levels of lead in water--a "first draw" sample and a "fully-flushed" sample. To evaluate the highest levels of lead exposure, the sample should be taken from the tap after water has been held in the pipes for several hours or overnight. A second sample, obtained after the water has flowed for three to five minutes, demonstrates if flushing the line decreases lead content substantially. You may be asked to take samples from all the drinking water taps in your home.
There are simple steps you can take if testing shows that flushing the tap reduces lead levels. You may want to use these if you think lead may be present in your plumbing system.
Flush the water taps or faucets. Avoid drinking water that has been sitting in the plumbing lines for more than six hours. The longer that water sits in pipes, the greater the exposure to lead and possible contamination. Before using water for drinking or cooking, run the cold water faucet for two to three minutes, until you can feel that water has become as cold as it can get. You should do this for each drinking water faucet. Allowing the water to run an extra 15 seconds after it feels cold should flush the service connector as well.
Use only cold water for cooking and drinking. Hot water dissolves lead more quickly than cold water. Using cold water is especially important if you are preparing baby formula. Heat the water you need for formula on the range or in the microwave oven.
Use bottled or distilled water. This water can be used for drinking and cooking if homes have lead pipes or if flushing the taps does not lower lead levels.
Treatments for removing high or persistent lead levels in water entering a household are reverse osmosis (RO) or distillation. The RO method forces water under pressure through a membrane formulated to reject certain substances. The simplest RO systems consist of a pump, the membrane, and a flow regulator. A water filter can be used with an RO system when the water is excessively hard.
Distillation units remove lead by boiling the water then collecting and condensing the steam. Many impurities are removed and nearly contaminate-free water is produced. Most home distillation units have small capacities, from one quart to one-half gallon of water per hour. Water with a high mineral content or suspended solids rapidly fouls the system, and the drinking water produced tastes rather bland. Distillation removes approximately 99 percent of the lead from water.
If the problem is determined to be caused by corrosion of pipes or other plumbing components, the corrosion can generally be halted by treating the water to increase the pH. This can be accomplished by installing a neutralizing filter in the water line before it enters the house or installing a solution injector at the well to inject soda ash. Soda ash injection will result in the precipitation of sodium bicarbonate and should be installed ahead of a filter to remove the pre- cipitant. In order to prevent corrosion it is usually desirable to increase the pH to 7.5 - 7.8.
Another treatment for corrosive water is to inject polyphosphates or sodium silicates. These compounds do not affect the pH, but they create a thin protective coating on the inside of pipes and other plumbing components which prevents the water from attaching the metal and leaching lead and other contaminants.
Activated carbon filters, sand filters, and cartridge or microfilter filters are not recom- mended or designed to reduce lead, according to the EPA. When lead is a problem, water softeners should not be connected to pipes leading to drinking water taps.
To reduce lead contamination of drinking water, alternative products must be used in plumbing systems of new homes. Tin-antimony (95/5 percent) or tin-silver (96/4 percent) solders are considered better quality but more expensive than tin-lead 50/50 percent solder. Both alternative materials provide a better seal than tin-lead solder, although the higher melting points of silver and antimony make these solders slightly more difficult to use.
Tin-antimony solder is not recommended on brass fittings since brass becomes brittle. A study of tin-antimony and tin-silver solders shows both metals are more resistant to corrosive-water leaching than lead solder.
Lead and Your Drinking Water, April, 1987. Office of Water, United States Environmental Protection Agency.
Lead in Drinking Water. Wagnet, and Ann Lemley. 1987. Cornell Cooperative Extension, Cornell University.
Lead: Water Quality Fact Sheet 6. Plowman, Faye T. Cooperative Extension, University of New Hampshire.
"The Pollutants That Matter Most Lead, Radon, Nitrate." Consumer Reports. January,1990: 30-32.
Lead and Copper Rule. June, 1991. Office of Water, United States Environmental Protection Agency.
The University of Georgia and Ft. Valley State College, the U.S. Department of Agriculture and counties of the state cooperating. The Cooperative Extension Service offers educational programs, assistance and materials to all people without regard to race, color, national origin, age, sex or disability.
Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, The University of Georgia College of Agricultural and Environmental Sciences and the U.S. Department of Agriculture cooperating.
