Electrochemical deposition of amorphous aluminum oxides on lead pipes to prevent lead leaching into the drinking water

Over 5000 public drinking water systems in the US are out of compliance with the Lead and Copper Rule. Lead
leaching from lead pipes is limited by the solubility of a naturally occurring scale. Changes in water quality may
cause this scale to become more soluble, releasing lead into the drinking water. We propose a novel electro-
chemical method to prevent lead leaching from lead pipes. In this method, an aluminum wire and an alkaline
phosphate electrolyte are inserted into the pipes. The pipes are then anodized for 2 h by using an external power
supply, resulting in the electrodeposition of an insoluble aluminum oxide layer on top of the preexisting scale.
This technology was tested on lead pipes from the EBMUD water distribution systems located in Berkeley, CA,
using recirculating synthetic and actual tap water for 120 days. The untreated pipes leached an average of 23 ppb
and 38 ppb of lead respectively, when using free chlorine and monochloramine as disinfection residuals. In
contrast, the treated pipes leached 3 ppb and 5 ppb respectively. These results suggest that the proposed
treatment has the potential to prevent lead leaching regardless of the disinfection residual and thus should be
further explored in a field trial.