Copper service lines remain a standard in drinking water systems due to their strength, formability, and long service life. For utilities, maintaining water quality in systems that include copper depends on a clear understanding of corrosion behavior, system chemistry, and regulatory requirements under the Lead and Copper Rule Improvements (LCRI).
Copper in drinking water can originate from both the distribution system and building plumbing. This includes copper service lines, utility-owned piping, and interior plumbing, including pipes, fittings, and fixtures. When undesirable conditions, such as the presence of aggressive chemicals, make water corrosive, or when flow conditions promote corrosion, small amounts of copper can dissolve from these materials into the water.
The National Sanitation Foundation (NSF) explains that this process is driven by corrosion, which occurs when water chemistry, solids, or high velocity interacts with metal surfaces. Factors such as pH (acidity), temperature, and contact time influence how much copper is released when the water is aggressive. Water chemistry that remains in pipes for extended periods can become aggressive if the system is not properly maintained.
Stagnation is a key variable. When water sits in pipes, in vacant buildings, or during periods of low use, copper levels can rise before the water is used. This is why sampling protocols are designed to capture first-draw conditions that reflect potential exposure.
Over time, copper plumbing can develop a natural internal layer (patina) that reduces the amount of copper released into the water. Maintaining stable water chemistry, proper velocity, and proper installation support this process and help limit variability across both the distribution system and building plumbing.
For utilities and project teams, copper levels at the tap reflect conditions across the full system, from distribution infrastructure to building plumbing. Managing those conditions through consistent water quality control is central to limiting copper release.
The U.S. Environmental Protection Agency (EPA) first established the copper action level of 1.3 mg/L, based on the 90th percentile of tap sampling results, under the Lead and Copper Rule in 1991. Unlike lead requirements, which have continued to evolve through subsequent rule revisions, the copper action level has remained unchanged.
Although the final Lead and Copper Rule Improvements (LCRI) update changes several compliance requirements, the most significant changes focus on lead, not copper. The final rule requires replacement of lead and certain galvanized service lines, strengthens tap sampling procedures, and lowers the lead action level. By contrast, copper remains regulated at the 1.3 mg/L action level established in 1991.
It is important to understand that the toxicological profiles of lead and copper resulting from drinking water exposure are very different, despite both being regulated under the same Lead and Copper Rule.
The bottom line is this: Because lead is toxic even at extremely low levels, the lead action level set in the Lead and Copper Rule is only 0.015 parts per million (15 parts per billion). This is eighty-seven times lower than the 1.3 parts per million action level set for copper.
The final LCRI includes a dedicated section on tap sampling for lead and copper and retains corrosion control treatment as a core compliance element. It also keeps service line inventory and public communication requirements within the broader rule framework, which matters for systems evaluating materials, sampling locations, and customer notification responsibilities.
While lead and copper plumbing materials have been delivering water to communities for thousands of years, researchers learned only in the 20th century that these two materials have very different toxicological profiles.
Thus, as mentioned earlier, although they are both regulated under the same regulatory framework of the Lead and Copper Rule, lead and copper differ greatly in the types of adverse health effects that may arise following drinking water exposure and in the concentrations at which these effects may occur.
Copper is an essential trace element:
Lead is a neurotoxin that can cause long-term health effects:
Corrosion control is the primary method for managing copper levels in drinking water systems, starting with proper design and installation and continuing as an ongoing operational function.
Effective corrosion control depends on proper system design and maintaining water chemistry conditions that support the formation and stability of a protective patina inside copper pipes. This patina often consists of copper oxides and carbonate-based compounds. Disruptions to this layer can increase copper release.
Key operational parameters include:
● pH control: Slightly alkaline conditions reduce copper solubility and support the formation of a patina
● Alkalinity and dissolved inorganic carbon: Promote carbonate scale development
● Oxidant management: Disinfectants influence surface reactions and scale composition
● Corrosion inhibitors: Compounds such as orthophosphate are used in some systems to reduce metal release
Corrosion control programs require continuous monitoring and adjustment. Changes in source water, treatment processes, or distribution system conditions can alter corrosion dynamics. CDA recommends evaluating these changes and maintaining optimized treatment.