Following EPA and State guidelines, we regularly monitor drinking water in the distribution system for lead to determine the effectiveness of our corrosion control program. The EPA action level for lead is 15 parts per billion (ppb) or 0.015 mg/L (equivalent to approximately 15 seconds of time in 32 years).
Analysis for lead is done from household taps and other locations throughout the distribution system where lead service lines exist or may be suspected based on system age. The sampling is done during the summer months when lead levels would be highest due to water temperature.
| Year | Lead 90th Percentile ppb |
|---|---|
| 1995 | 10.0 |
| 1996 | 9.0 |
| 1998 | 9.0 |
| 2001 | 8.0 |
| 2004 | 2.0 |
| 2007 | 1.9 |
| 2010 | 1.2 |
| 2013 | 1.5 |
| 2016 | <1.0 |
| 2019 | 1.6 |
| 2022 | 1.0 |
Lead Action Level ppb: 15.0
Before 2019, we were unable to detect lead in our laboratory below one part per billion, even with the best available technology - 1 part per billion (ppb) is equivalent to 1 second in approximately 32 years. Due to advances in technology, we are now able to detect lead more precisely and accurately at parts per trillion (ppt) levels – 1 part per trillion (ppt) is equivalent to 1 second in almost 32,000 years. This means that where we once would not have detected any lead, we are now able to. As a result, our 2019 and 2022 analysis reflects an increase in sensitivity, precision and accuracy rather than an increase in the level of lead in our water.
Public Water Systems that provide optimal corrosion control treatment and system monitoring showing that lead levels are at or below the action level (15 ppb) qualify for reduced monitoring. Compliance is determined by comparing the 90th percentile of results. Due to the proven success of our corrosion control program, in accordance with State and Federal regulation, Metro Water Services samples for lead every three years.
If you believe you may have lead service lines and are interested in participating in future lead sampling or studies, please contact us at 615-862-4591 or email [email protected].