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Significance of building and plumbing specifics on trace metal concentrations in drinking water

University of British Columbia

Samples were taken from 72 high-rise apartment suites (6 suites in 12 individual high-rise towers) and 60 single-family houses located within the Greater Vancouver Regional District. The influence of the following factors on trace metal concentrations in 1-L first-flush drinking water samples and running hot water samples was investigated: building height, location, plumbing age, type of plumbing and type of building. Results of this survey show that with the exception of building height, all factors had a correlation with one or more of the trace metals investigated. The trace metals examined were lead, copper, iron and zinc. Lead was influenced primarily by building type, copper by plumbing age and type of plumbing and iron by location. Elevated lead levels were associated with high-rise samples. New copper plumbing systems resulted in high copper levels. Highest iron levels in the drinking water were measured in the East location. Zinc did not show a distinct correlation with any of the factors investigated. Brass faucets were the primary source of zinc in tap water. They also contributed substantially to the lead detected in the 1-L first-flush sample. Metal concentrations measured in high-rise and house samples were compared with U.S. Environmental Protection Agency's (USEPA) maximum contaminant levels (MCLs) and the proposed no-action level for lead1. In high-rise samples, the 0.01 mg/L "no-action" proposed for lead was exceeded in 43% of the samples and 62% of the samples exceeded the current 1.0 mg/L MCL standard for copper. In single-family house samples, these values were 1 Compliance with the proposed 0.01 mg/L no action limit for lead is based on a sample average. Individual samples may exceed this value and still be in compliance. 47% and 73%, respectively. The average lead concentration for all high-rise samples was 0.020 mg/L and 0.013 mg/L for house samples. Regulatory levels stated above would still be exceeded in 6% of the cases for lead and 9% of the cases for copper, even after prolonged flushing of the tap in a high-rise building. In all cases associated with single-family houses, flushing the cold water tap for 5 minutes was successful in achieving compliance levels.

Text

2010-09-27

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http://hdl.handle.net/2429/28724

Civil Engineering

University of British Columbia

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