Distribution Systems Corrosion: Lead | Risk Management Research

Lead

Lead is a heavy, soft, and malleable metal found in natural deposits (such as ores containing other elements) and has no characteristic taste or smell. It is used to make pipes, cable sheaths, batteries, solder, paints, and glazes. Where drinking water is concerned, lead has been used to produce service lines and solder (both banned since 1988), and a variety of brass pipes and plumbing devices.

Effects of Lead on Human Health and How It Enters Drinking Water
Lead poses a significant health concern. For infants and children, exposure to high levels of lead in drinking water can result in delays in physical or mental development, even when lead levels in blood are not highly elevated. For adults, it can result in high blood pressure, kidney problems, or even cancer. Although the main avenues of exposure to lead are ingesting paint chips and inhaling dust, EPA estimates that 10 to 20 percent of human exposure to lead may come from lead in drinking water.

Most lead enters our drinking water through the interaction of the water and plumbing materials containing lead, that is, through corrosion and the solubilization of lead-based corrosion by-products. Water chemistry, the age of the piping, and the amount of exposed lead at the surface of the material in contact with the water are the most important factors contributing to lead leaching into our drinking water. Plus, trace amounts of certain soluble contaminants, including lead, can be adsorbed by corrosion deposits within distribution systems. Changes in water chemistry or physical changes within the system can later cause concentrated amounts of these contaminants to be rereleased into the water supply.

Although lead is rarely found in source water, lead mining and smelting operations may contribute to the contamination of source water in certain areas.

To prevent lead from entering our drinking water, there are three categories of control:

Physical control is the removal of lead-containing materials or the limiting of lead content in materials.
Point-of-use control is the use of devices attached to water taps or in lines near water outlets. These devices include filter units, ion exchangers, reverse osmosis units, and adsorber cartridges.
Chemical treatment control is the treatment of water as it comes from the plant or when water is treated in a building. For example, pH and alkalinity adjustment, phosphate addition, and silicate addition are chemical approaches used to reduce lead levels in water.

Regulations

Regulations to reduce human exposure to lead are:

The Safe Drinking Water Act of 1974 – This is the main federal law that ensures the quality of our drinking water. Under this act, EPA sets standards for drinking water quality and oversees the states, localities, and water suppliers who implement those standards.
The Lead Contamination Control Act of 1988 – This act amended the Safe Drinking Water Act by adding new requirements to regulate the safety of drinking water. Specifically, lead-lined drinking water coolers were recalled.
The Lead and Copper Rule of 1991 – This rule requires lead and copper levels to be minimized in drinking water, primarily by reducing water corrosivity. It establishes an action level of 0.015 milligrams per liter (mg/L) for lead and 1.3 mg/L for copper in 90 percent of the first-draw water samples taken at specifically identified sites and after six hours of stagnation. (Refer to the Lead and Copper Rule targeting and sampling requirements.) The action level is the lowest level to which water utilities can reasonably be required to control lead if it occurs in drinking water at their customers’ home taps. (Note: An action level exceedance is not a violation but can trigger other requirements such as monitoring and treatment.)
The Lead and Copper Rule Revisions of 2001 and 2006 – These revisions streamline and reduce monitoring requirements and the reporting burden. In addition, they address implementation problems and issues arising from legal challenges.

These regulations are called the National Primary Drinking Water Regulations. All public water utilities are required to abide by them.

Most regulations require sampling at entry points to the distribution system to ensure conformance; however, because increased levels of lead in drinking water are primarily due to the corrosion of distribution and household plumbing materials, water utilities must collect water samples at kitchen or bathroom taps of residences and other buildings. This requirement significantly complicates sample collection and requires that water utilities coordinate with consumers to ensure that proper sampling and conformance is achieved.

If the levels of lead in your drinking water are found to be consistently above the action level, your water supplier must take steps to reduce the amount of lead so that it is consistently below that level. Additional actions, such as providing alternative drinking water supplies, may be required to prevent serious risks to public health.

Technical Contact:

Darren Lytle
(513) 569-7432

Michael Schock
(513) 569-7412

Michelle Latham
(513) 569-7601

Lead

Regulations

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