Contaminant · metal
Lithium in drinking water
A naturally occurring alkali metal found in groundwater, especially in arid western states.
highest recorded single-sample basis; sampled 2023–2025. Source: EPA records; Creekside Village MHP (NY4710781).
What the rules say
Lithium has no federal drinking water limit. EPA's non-regulatory health reference level is 10 µg/L (one significant digit, so EPA counts results above 15 µg/L as exceeding it). Lithium occurs naturally in groundwater and is the most frequently detected UCMR 5 contaminant.
What EPA's assessment says
EPA's health reference level is derived from a 2008 provisional toxicity value based on effects seen at therapeutic lithium doses; EPA notes the assessment is provisional.
Read the EPA source for Lithium.
Across the country
EPA tested 10,313 water systems for Lithium and found it in 3,773. Half of the systems that found it measured less than 21 ppb, and one in ten measured more than 67.4 ppb.
EPA's final UCMR 5 occurrence file contains 66,675 Lithium results from 10,313 systems. 18,939 results were at or above the minimum reporting level, across 3,773 systems. Among detections, the median was 21 ppb and the 90th percentile was 67.4 ppb.
3,547 systems had a result at or above the reference on the page's stated comparison basis. For contaminants with a limit, that basis is the yearly average at the highest sampling location, not the highest single sample.
Systems with the highest recorded Lithium results
| System | State | Population served | Recorded value | Records / periods |
|---|---|---|---|---|
| Creekside Village MHP NY4710781 | New York | 115 | 921 ppb | 2 |
| Waterpro INC UTAH18006 | Utah | 33,100 | 960 ppb | 8 |
| Arizona Water Co - Apache Junction AZ0411004 | Arizona | 62,055 | 796 ppb | 4 |
| Aqua Pa Water Co Honesdale PA2640018 | Pennsylvania | 5,500 | 702 ppb | 8 |
| Phoenix International Raceway AZ0407406 | Arizona | 4,500 | 620 ppb | 2 |
| Bermuda Water Company INC AZ0408063 | Arizona | 25,000 | 580 ppb | 18 |
| Mesa City of AZ0407095 | Arizona | 466,000 | 525 ppb | 70 |
| Santa Ana Westside 063503118 | New Mexico | 10,691 | 540 ppb | 4 |
| Bernalillo Water System NM3508923 | New Mexico | 10,948 | 537 ppb | 4 |
| Cal Am - Oakhurst CA2010007 | California | 3,693 | 474 ppb | 8 |
| City of Buckeye - Valencia Town Division AZ0407078 | Arizona | 30,377 | 468 ppb | 2 |
| Indianola Water Supply IA9133075 | Iowa | 15,833 | 480 ppb | 2 |
| Vermillion SD4600342 | South Dakota | 11,695 | 440 ppb | 2 |
| Rio Rancho Water & Ww Services NM3509623 | New Mexico | 107,350 | 467 ppb | 14 |
| Wapello Rural Water Assoc. IA9000742 | Iowa | 17,263 | 420 ppb | 3 |
| West Des Moines Water Works IA7785007 | Iowa | 73,959 | 380 ppb | 6 |
| Pima Utilities AZ0407120 | Arizona | 20,000 | 381 ppb | 6 |
| Woodridge Village NY5203348 | New York | 902 | 335 ppb | 4 |
| Laguna Valley 063503111 | New Mexico | 4,500 | 343 ppb | 6 |
| Arizona Water Co - Pinal Valley AZ0411009 | Arizona | 134,432 | 353 ppb | 20 |
| Lower Rio Grande Pwwa South Valley NM3502407 | New Mexico | 11,542 | 335 ppb | 16 |
| Pa Amer Water Co Lake Scranton PA2359008 | Pennsylvania | 137,142 | 324 ppb | 12 |
| Tri County SUD TX0730004 | Texas | 5,353 | 325 ppb | 4 |
| Florence Water Company AZ0411017 | Arizona | 15,900 | 320 ppb | 9 |
| Globe City of AZ0404008 | Arizona | 7,536 | 308 ppb | 6 |
Filters and testing
No NSF/ANSI certification claim exists for lithium; reverse osmosis (NSF/ANSI 58) reduces dissolved minerals generally
A standard number by itself is not a contaminant claim. Check the product's current certification listing and performance data sheet for Lithium or the specific contaminant you want to reduce. A utility-level record is not a test of your own faucet.