Over the Lead Limit Before, Under It Now: What That Means

Most systems that went over came back down

2,878 community water systems have at least one monitoring period over 15 ppb on file with EPA. In the latest period, 2,326 of them are back at or under the action level, and 770 now report lead as not detected.

What usually brings it down

An exceedance triggers required steps: corrosion-control treatment that coats the inside of pipes, public education, more sampling, and replacement of some lead lines. Corrosion control works fast, so a drop within a period or two is normal. It lowers what leaches from lead pipes; it does not remove them.

Why it still matters for your house

Lead in tap water comes from the pipes, not the source. A system that went over before had lead somewhere in the plumbing of the homes it sampled, and unless those lines were replaced they are still there. If the treatment changes, or construction disturbs a line, levels can come back up - which is what happened in Flint and in Washington, DC. On a system with a past exceedance, test your own tap and look up your address in the service line inventory, whatever the latest number says.

Examples

Some of the largest systems that went over and are now under: Atlanta, GA (1.4 ppb), Veolia Water New Jersey Hackensack, NJ (5.8 ppb), Boston Water And Sewer Commission (Mwra), MA (7.96 ppb), Portland Water Bureau, OR (5.01 ppb), Pittsburgh Water & Sewer Auth, PA (2 ppb). Each page shows the full history, period by period.

Where to go next

See the range across large systems: Aurora, IL, Metropolitan Utilities District, NE, Washington Suburban Sanitary Commission, MD.

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