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Destabilization of Lead Pipe Scales in a Long-Term Vacant Home
Citation:
Desantis, M. Destabilization of Lead Pipe Scales in a Long-Term Vacant Home. EPA Small Systems Webinar, Cincinnati, Ohio, March 26, 2019.
Impact/Purpose:
Many communities around the US are concerned because of the presence of legacy lead service lines in their drinking water systems. Cities with lead (IV) scales and large stocks of vacant homes might be interested in the results of this study. Testing of the water in long-term vacant homes that will be reoccupied could provide helpful information. Additional research is being conducted to provide more information about how long it takes to reestablish stable lead (IV) scales.
Description:
Lead (IV) corrosion scales have been found in approximately 30% of lead service line pipes from across the US that have been examined by ORD researchers. These scales are relatively insoluble which prevents lead from being released into the water, but this stability requires maintaining adequately high ORP and sufficiently high pH. This presentation discusses a case study of an unoccupied house in Cincinnati, OH, where lead (IV) scales are common. The study shows how the mineralogy of these lead pipe scales can change over extended time periods during which there is no water flow or contact with disinfectant residual, resulting in dramatically increased water lead levels. Flushing to restore the scale was also investigated. Regular hourly flushing of the premise plumbing and service line for a one-year period reduced lead concentration but did not return them to their pre-vacancy levels. This study shows that conversion of Pb(IV) scales is a potential problem for communities with a large stock of older vacant homes that might be reoccupied.