Lithium in Treasure Valley drinking water
12 of 14 systems that tested for it in the last 36 months detected it. Lithium is an inorganic contaminant. Some results are from EPA UCMR monitoring, not a claim it is in every tap. Certified filters are in the list.
Detected in a number of Treasure Valley systems under UCMR 5, consistent with the region's geothermal groundwater.
| System | County | 36 mo max | Latest | Status | Last sample |
|---|---|---|---|---|---|
| Meridian Water Department | Ada | 99.5ppb | 93.1ppb | Detected | 2025-09-24 |
| Garden City Water and Sewer System | Ada | 78.1ppb | ND | Detected | 2024-10-14 |
| City of Emmett | Gem | 56.0ppb | 52.0ppb | Detected | 2025-12-02 |
| City of Nampa | Canyon | 42.1ppb | 14.1ppb | Detected | 2025-10-28 |
| City of Eagle (Eastern Zone) | Ada | 32.0ppb | 32.0ppb | Detected | 2024-11-12 |
| Veolia Water Idaho | Ada | 24.3ppb | ND | Detected | 2024-02-26 |
| City of Kuna | Ada | 21.0ppb | 16.3ppb | Detected | 2025-04-16 |
| Star Sewer and Water District Water System | Ada | 20.0ppb | 18.4ppb | Detected | 2024-12-09 |
| Capitol Water Corp. | Ada | 19.0ppb | 16.0ppb | Detected | 2023-12-06 |
| City of Caldwell | Canyon | 13.0ppb | 12.0ppb | Detected | 2025-08-11 |
| City of Eagle (Western Zone) | Ada | 11.0ppb | 9.2ppb | Detected | 2024-10-21 |
| City of Middleton | Canyon | 9.9ppb | ND | Detected | 2023-09-19 |
Limits
- Regulated
- No federal MCL or action level on file
Lithium is not regulated. It was monitored under UCMR 5; EPA has not set a health advisory.Agency language as recorded in the contaminant reference.
Removal methods in the reference list: reverse osmosis. A method name is not a product certification.
By city: Lithium in Boise City drinking water, Lithium in Meridian drinking water, Lithium in Garden City drinking water, Lithium in Emmett drinking water, Lithium in Nampa drinking water, Lithium in Eagle drinking water, Lithium in Kuna drinking water, Lithium in Star drinking water, Lithium in Caldwell drinking water, Lithium in Middleton drinking water.
2 groundwater zones in the region have confident (grade A or B) estimates for Lithium. See well estimates by ZIP.
Numbers are the system's samples at its taps and wells, not yours. Lead and copper are 90th percentiles from sampled homes. Well pages are nearby-sample estimates. Health text restates EPA and DEQ. Methodology.