To monitor lead levels, MWRA and your local water department test tap water in up to twenty-five homes in each community.
Lead results for the entire system and for each community are complied by MWRA, with an average of 440 samples taken for the entire system. The regulations require that a system our size – serving over 2 million people – take only 100 samples. New York City, with around 5 times as many customers, takes only 100 samples.
We have agreed with our state regulators at the Department of Environmental Protection to uniformly sample more than 4 times as many homes across the service area to get a better idea of how our corrosion control treatment is working.
But not just any homes are sampled. Under Environmental Protection Agency regulations, homes that are likely to have high lead levels - usually older homes likely to have lead service lines or lead solder – must be tested. Also, only first flush samples, water most likely to have lead, are sampled. The EPA rule requires that 90% of these sampled homes must have lead levels below the Action Level of 15 parts per billion (ppb).
Lead levels in sampled worst case homes have dropped steadily since 1992. Average lead levels at sampled worst-case homes have dropped nearly 90%. Also, the proportion of samples has also changed over time.
As the pie charts above show, the number of worst case homes that have lead levels that are less than 1 ppb and 5 ppb has increased dramatically, as well over 80% of the samples are now less than 5 ppb.
If you have questions or would like more information about lead in drinking water, please call our Water Quality Hotline: 617-242-5323, or email Joshua Das, Project Manager, Public Health.
Updated February 28, 2017 1:23 PM