No abstract

Simplistic conventional models predict that a greater mass of lead will be released from lead pipes exposed to higher velocity and flow durations. However, if galvanic Pb-Cu connections are present, or if a highly protective Pb(IV) scale can be formed, reduced flow can markedly increase the mass of lead release to water and resultant consumer exposure. Three chemical mechanisms were identified that can reduce lead release at higher flow including (1) formation of Pb(IV), (2) potential reversal of Pb:Cu couples, after which galvanic corrosion sacrifices copper and lead is protected, and (3) reduced formation of corrosive microenvironments at lead surfaces in galvanic couples. Potential reversal occurred only in the presence of free chlorine with continuous flow, and it did not occur with chloramine, with intermittent flow, or if orthophosphate was present. For both disinfectants, electrochemical measurements supported a mass balance of lead release demonstrating that a greater total mass of lead release occurred with intermittent flow than with continuous flow.

A new elementary school with persistent elevated copper corrosion by‐product release evaluated pH increase, orthophosphate dosing, and granular activated carbon (GAC) treatment as potential corrosion control measures using bench‐scale experiments. Removal of natural organic matter (NOM) with temporary GAC treatment facilitated the formation of a copper scale with a permanently diminished (> 85%) solubility via an accelerated natural scale‐aging process. Increasing the pH and adding a high dose of orthophosphate were also effective for decreasing copper release but presented significant long‐term drawbacks, and their benefits were reversed if the treatments were discontinued. Temporary GAC treatment may be a holistically attractive option to reduce copper corrosion problems in new construction in certain waters with high levels of NOM.

Key TakeawaysA 2019 US corrosion control survey benchmarks recent utility perspectives before the release of the proposed LCR revisions, providing insight on regulatory impacts.Rates of orthophosphate use continue to increase, and the results add to evidence that orthophosphate is effective for controlling lead release.The primary challenge facing utilities is coordinating compliance sample collection, and the greatest priority is ensuring optimal corrosion control treatment.

Key Takeaways The Colorado Department of Public Health and Environment developed a standardized protocol for corrosion testing procedures that is available as a resource for utilities. Immersion testing can be used to evaluate corrosion mechanisms, determine optimal corrosion control treatment, and examine the impacts of source water or treatment changes, while greatly reducing the cost and complexity compared with pipe loop testing. Exploring various resources, such as academic research, first‐hand utility experience, and water industry guidelines, can help a utility select the corrosion testing approach that best suits its needs and circumstances.