Anne Sandvig, Pierre Kwan, Gregory Kirmeyer, Barry Maynard, David Mast, R. Rhodes Trussell, Shane Trussell, Abigail Cantor, and Annette Prescott

OBJECTIVES:

The objective of this research project was to evaluate the contribution of lead service lines and utility and customer-owned plumbing components to Lead and Copper Rule (LCR) compliance issues. The results of this project also address the broader long-term goals of moving the industry towards a new "lead free" future and providing information that can be directly applied to future regulatory reviews of the LCR.

BACKGROUND:

Implementation of the Lead and Copper Rule (LCR) has resulted in significant reductions in first liter standing lead levels measured at the tap in the United States. However, there are still utilities that have implemented optimal treatment but may still experience lead levels at or near the action level for lead, or those that would like to go a step further in reducing lead levels measured in their system by proactively replacing lead source materials. For these utilities, and water works and regulatory communities as a whole, an understanding of the contributions that various lead based materials may have on lead levels measured at the tap would be useful.

HIGHLIGHTS:

For sites with lead service lines, the service contributes the greatest percentage of lead measured at the tap, followed by the premise piping, faucet, and the meter. For sites without lead service lines, the premise piping contributes the greatest percentage of lead measured at the tap, followed by the faucet.

When a lead service line is present, it is likely a significant and possibly controlling factor in the total amount of lead measured at that site, and the mass of lead contributed by individual lead sources.

Non-leaded faucets may contain component parts that are made from alloys that contain lead and may therefore be subject to lead release. Also, variability in faucets can affect the release of lead from new faucets and the intermittent release of lead over time as the faucets age, making it difficult to estimate 'typical' lead release under specific water quality conditions.

Scale results were specific to the water quality and materials compositions at each specific site; however, they provide needed research on the formation and characteristics of scales that form on the interior of pipes, fittings, and components in drinking water systems, how these scales affect release of lead, and an understanding of models of lead release and uptake that result in lead measured at the tap.

APPROACH:

This project utilized information from historical literature, conducted a national survey of lead source characteristics, completed case studies of lead source removal and corrosion treatment effectiveness, and completed field and pilot study activities designed to estimate the contributions of various lead sources to lead levels measured at the tap. This information was used to evaluate the relative contribution of various lead sources to lead levels at the tap and how these contributions might affect compliance with the LCR. In addition, an assessment of the impact of pipe cutting tools was completed to provide guidance on the best methods for removing lead service lines. The composition of scales built up on lead source materials was evaluated to expand the knowledge base related to identification of compounds that form on leaded materials in drinking water systems and correlations between these scales and distributed water quality conditions.

RESULTS/FINDINGS:

Lead source contributions will be influenced by the physical characteristics of the source (length, diameter, surface area), water quality conditions, water use and hydraulic patterns, and mixing and dilution effects as the water flows during sampling. In addition, it is hypothesized that the presence of a lead service line at an individual site may elevate the contribution of individual sources by providing an additional source of lead, either by seeding the premise system with lead or introducing lead derived from the service at the start of the stagnation period.

The most effective way to reduce the total mass of lead measured at the tap is to replace the entire lead service line, followed by replacement of lead sources in the premise piping, the faucet, and then the meter. Replacement of faucets and end-use fittings may or may not improve lead levels at the tap; however, it may be appropriate at sites without lead service lines that may experience elevated lead levels in first draw samples. Elevated lead levels may occur immediately after lead source replacement and may persist for longer periods of time dependent on the materials and water quality at each site, and the amount of disturbance during replacement.

IMPACT:

Corrosion control treatment is likely still the best and most cost-effective way to comply with the requirements of the LCR. However, the consumer's portion of the lead service line, which is beyond the jurisdiction of local water utilities, remains an important unresolved source of lead. Common sense tells us that, in the end, lead source removal is the most certain route to eliminating lead in drinking water. The water industry has learned a great deal about methods of minimizing the release of lead from lead surfaces exposed to water, and it has made a great deal of progress in removing lead services. This report clearly demonstrates that the consumer's portion of the lead service line remains an important unresolved source of lead. This issue is beyond the jurisdiction of local water utilities and other resources will be required if it is to be resolved.

RESEARCH PARTNER:

U.S. Environmental Protection Agency

PARTICIPANTS:

Fifteen utilities from the United States, Canada, and the United Kingdom participated in this project.