Reducing Lead Levels In Drinking Water


This article outlines issues involved with lead in drinking water, including the Causes of Lead Contamination, the New EPA Lead Standards, and In-Home Water Treatment Units that have been proven to reduce lead levels.



Lead exposure is a major health concern that is gaining recognition across the country. Magazines, newspapers, television, and radio have been spreading the word about its risks, and although only 20 percent of lead exposure is caused by drinking water, the nation has recently focused its attention there.

And there is just reason for concern. The U.S. Environmental Protection Agency (EPA) calls lead "a highly toxic metal the agency considers a major public health threat."

Although in adults lead can increase blood pressure and interfere with hearing, children are at a greater health risk due to lead ingestion than adults. In children, lead can interfere with the formation of red blood cells, delay physical and mental development, and impair mental abilities.

At high levels of exposure, lead can cause anemia, kidney damage, and mental retardation.

Pregnant women should also be especially cautious about lead exposure, as it can cause premature birth, and reduce the birth weight of babies.

The good news is that it is possible to reduce lead levels in drinking water for several reasons:

* Determining which homes are likely to have high lead levels in drinking water is relatively easy;

* The EPA recently set stricter regulatory standards for lead;

* Several in-home water treatment technologies that reduce lead are available to consumers.

In fact, the national Centers for Disease Control considers lead to be the country's number one preventable pediatric health problem.


Causes of Lead Contamination


The greatest contributions to childhood exposure to lead are lead-based paint, urban soil and dust, and drinking water.

Lead rarely occurs naturally in drinking water. Instead, lead contamination usually occurs at some point in the water delivery system. It is most commonly caused by the corrosion of lead service connections, pipes, or lead solder used to join copper pipes in the home. Homes that are less than 10 years old and have lead solder or homes that are connected to the water main by a lead service line are more likely to have higher levels of lead in the water, according to the EPA.

In 1986, lead was banned from use in pipes and solder in public water systems. It was also banned in household plumbing and limited in brass fixtures. Although illegal use of solder does continue, the EPA is considering further restrictions on the sale or manufacture of lead solder and brass fixtures that contain lead.

Water is known as the universal solvent. As it travels, it picks up traces of most things in its path, which often includes calcium and magnesium, thetwo minerals that cause what is commonly referred to as "hardness" in water. Hardness is usually measured in grains per gallon (gpg). The greater the grains per gallon, the greater the water hardness.

Hard water has many disadvantages. It tends to clog pipes, damage kitchen and bath fixtures and appliances, leaves a film on bathtubs and shower tiles, and does not rinse well from skin when showering. For these reasons and others, many consumers choose to install a water softener in their home.

The most common type of softener uses cation exchange. In this process, the softener exchanges the hard calcium and magnesium ions for neutral sodium ions, thus reducing the hardness of the water.

Lead levels may be increased in homes that have naturally soft water. It is important, however, to make the distinction between a naturally soft water and softened water from a water softening device. Lead in drinking water is most commonly caused by the corrosion of lead plumbing materials. Water varies in its characteristics, and some water is naturally more corrosive than others.

Several factors cause water to be more corrosive. These factors include acidity, high temperature, low total dissolved solids (TDS) content, and high amounts of dissolved oxygen.

According to the U.S. Geological Survey, more than 85 percent of the United States has hard water. However, in sections of New England and the far Northwest where naturally soft water is found, water tends to be corrosive because of acidity, low TDS content, and the presence of dissolved oxygen. Since this natually soft water is corrosive, it is more likely to cause the corrosion of lead plumbing materials.

In contrast, the process of softening water does not affect the characteristics that lead to corrosion, and therefore should not contribute to corrosion or to lead exposure. Water softening does not cause corrosion. In fact, if lead is found to be entering the water before it reaches the home, a water softener can significantly reduce the lead level.


New EPA Lead Standards

On May 7, 1991 the EPA set new nationwide standards to lower the level of lead in drinking water. This action is the agency's most significant effort to reduce lead exposure since it phased out leaded gasoline.

In addition to setting the new enforceable standard, the EPA also set a Maximum Contaminant Level Goal (MCLG) of zero for lead in drinking water. An MCLG is a nonenforceable health goal established by the EPA, and implies the optimal level of the substance in drinking wter at which no adverse health effects are anticipated to occur. In many instances, reducing the contaminant to the MCLG may not be feasible for economic reasons; therefore, the enforceable standards may be set at a higher level, as is the case with lead. According to the EPA, the enforceable standards are safe but not optimal.

The new enforceable lead standards are 10 times more protective than the present regulations. Currently, the allowable lead level in drinking water is 50 parts per billion (ppb). The new standards call for an "action" level of 15 ppb, which means that water systems that exceed the 15 ppb in 10 percent of the homes sampled will be required to take action to reduce lead levels.

Monitoring of the new standards will begin in 1992. Approximately 79,000 public water suppliers in the U.S. will be required to monitor for lead at household taps. the monitoring will be of first-draw water, which commonly contains the most lead, and will take place at homes with the highest risk: those with lead service lines or lead solder applied since 1982. Cities of more than 100,000 people will monitor 100 high-risk homes twice a year.

The EPA also notes that all 800 large water systems in the U.S. will be required to begin corrosion-control programs by 1993, regardless of how many households show 15 ppb in tap water. These programs may include adding lime or soda ash to the water to reduce its acidity or using chemicals that form protective coatings inside the pipes. Some large systems have already begun these programs in anticipation of the new standards.

Large water systems - those that serve more than 50,000 people, are required to begin monitoring lead levels by January 1, 1992. Medium systems serving 3,300 to 50,000 people must begin monitoring by July 1, 1992; and small systems that serve less than 3,300 people will begin by July 1, 1993.

A public education program developed by the EPA will inform consumers how to minimize lead exposure in drinking water. Any water system that exceeds the 15-ppb action level at any time after monitoring begins will be required to participate in this program.

The EPA estimates that approximately 40,000 water systems will fail to meet the new action level standards.


In-Home Water Treatment Units

For consumers who wish to take the matter into their own hands, several technologies that treat drinking water in the home have been proven to significantly reduce lead, in addition to reducing other contaminants as well. These technologies include reverse osmosis, distillation, water softening, and solid block and precoat adsorption filters, which are made with carbon or activated alumina.

Drinking water treatment units are often composed of a combination of these technologies. The units vary considerably in size, and may fit under the sink or attach directly to the faucet.

The new EPA standards will reduce exposure to lead in drinking water for those who get their water from public water supplies. However, those who obtain their water from private wells may also want to test their water for lead and take appropriate action based on the results. Water can be tested by a local health authority, a state- or EPA-certified, or other reputable laboratory.

If the test reveals that lead is entering the system from household plumbing, as opposed to sources outside the home, point-of-use or single-tap drinking water alternatives may provide the best solution for reducing the lead level. These alternatives include reverse osmosis, distillation, and solid block or precoat adsorption filters. As stated earlier, if the source is outside of the home, water softeners can reduce lead.

Water treatment units can help reduce a number of contaminants from drinking water. However, if lead is the main concern, be sure to check that the specific product will reduce lead. For example, while filters can reduce many contaminants, only solid block - and precoat adsorption filters in particular - are certified to reduce lead.

Consumers may want to consult the National Sanitation Foundation (NSF) or the Water Quality Association (WQA) for information about water quality improvement technologies. Both organizations test products voluntarily submitted by manufacturers.

NSF, based in Ann Arbor, Michigan, tests products for the removal of a number of contaminants, including lead. WQA tests products for performance claims, including durability of the product, performance, longevity, taste, color, and odor of treated water. Both NSF and WQA produce listings of those products which pass the testing.For all the technologies, be sure to check the manufacturer's literature for treatment and maintenance specifications.

Lead is a major health risk in the United States, but fortunately there are several steps that can be taken to reduce that risk.


This article first appeared in the WaterReview Consumer Report, (1991)

Volume 6, No. 2; a publication of the Water Quality Research Council;

Copyright 1991, 1995 by the WQA. All rights reserved.



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