This is a rebuild of Drinking Water Watch and not yet the official record. Use the agency’s current Drinking Water Watch for anything you need to rely on.
Lead and copper
MS0620010 , Sebastopol Water Association
Every monitoring period on record is listed here. This page applies no date range. The same list limited to the last two years.
| Analyte | Monitoring period | Samples | 90th percentile | Facility | Data quality |
|---|---|---|---|---|---|
| Copper | Jan 1, 2023 – Dec 31, 2025 | 20 | 0.237 mg/l | DS000 | Accepted |
| Lead | Jan 1, 2023 – Dec 31, 2025 | 20 | 0.0012 mg/l | DS000 | Accepted |
| Copper | Jan 1, 2020 – Dec 31, 2022 | 20 | 0.265 mg/l | DS000 | Accepted |
| Lead | Jan 1, 2020 – Dec 31, 2022 | 20 | 0.0021 mg/l | DS000 | Accepted |
| Copper | Jan 1, 2017 – Dec 31, 2019 | 22 | 0.3073 mg/l | DS000 | Accepted |
| Lead | Jan 1, 2017 – Dec 31, 2019 | 22 | 0.0018 mg/l | DS000 | Accepted |
| Copper | Jan 1, 2014 – Dec 31, 2016 | 20 | 0.3139 mg/l | DS000 | Accepted |
| Lead | Jan 1, 2014 – Dec 31, 2016 | 20 | 0.002 mg/l | DS000 | Accepted |
| Copper | Jan 1, 2011 – Dec 31, 2013 | 20 | 0.3418 mg/l | DS000 | Accepted |
| Lead | Jan 1, 2011 – Dec 31, 2013 | 20 | 0.0021 mg/l | DS000 | Accepted |
| Copper | Jan 1, 2008 – Dec 31, 2010 | 20 | 0.5109 mg/l | DS000 | Accepted |
| Lead | Jan 1, 2008 – Dec 31, 2010 | 20 | 0.0028 mg/l | DS000 | Accepted |
| Copper | Jan 1, 2005 – Dec 31, 2007 | 20 | 0.4447 mg/l | DS000 | Accepted |
| Lead | Jan 1, 2005 – Dec 31, 2007 | 20 | 0.0022 mg/l | DS000 | Accepted |
| Copper | Jan 1, 2002 – Dec 31, 2004 | 20 | 0.4272 mg/l | DS000 | Accepted |
| Lead | Jan 1, 2002 – Dec 31, 2004 | 20 | 0.0027 mg/l | DS000 | Accepted |
| Copper | Jan 1, 1999 – Dec 31, 2001 | 20 | 0.317 mg/l | DS000 | Accepted |
| Lead | Jan 1, 1999 – Dec 31, 2001 | 20 | 0.003 mg/l | DS000 | Accepted |
| Copper | Jan 1, 1996 – Dec 31, 1998 | 20 | 0.203 mg/l | DS000 | Accepted |
| Lead | Jan 1, 1996 – Dec 31, 1998 | 20 | 0.004 mg/l | DS000 | Accepted |
| Copper | Jan 1, 1995 – Dec 31, 1995 | 20 | 0.128 mg/l | DS000 | Accepted |
| Lead | Jan 1, 1995 – Dec 31, 1995 | 20 | 0.004 mg/l | DS000 | Accepted |
| Copper | Jan 1, 1994 – Dec 31, 1994 | 20 | 0.162 mg/l | DS000 | Accepted |
| Lead | Jan 1, 1994 – Dec 31, 1994 | 20 | 0.004 mg/l | DS000 | Accepted |
| Copper | Jan 1, 1993 – Jun 30, 1993 | 40 | 0.334 mg/l | DS000 | Accepted |
| Lead | Jan 1, 1993 – Jun 30, 1993 | 40 | 0.004 mg/l | DS000 | Accepted |
| Copper | Jul 1, 1992 – Dec 31, 1992 | 40 | 0.34 mg/l | DS000 | Accepted |
| Lead | Jul 1, 1992 – Dec 31, 1992 | 40 | 0.003 mg/l | DS000 | Accepted |
No date of receipt is recorded for any of these summaries.
What the 90th percentile is
The 90th percentile of all samples collected from the distribution system is the standard that the US Environmental Protection Agency has chosen for determining compliance with the Lead and Copper Action Level under the federal Lead and Copper Rule. The 90th percentile is determined by ranking all sample results from lowest to highest and finding a result that is 90% of the number of sample results from the top. For example, if there are 10 sample results, the 90th percentile would be the 9th sample result from the top.
From the help text published with these pages.