Lithium in Connecticut Drinking Water
Ranked by max lithium detected (µg/L) · UCMR 5 data (2023–2025) · Data from EPA SDWIS & UCMR
Lithium in Connecticut: what the data shows
Connecticut has 23 cities with lithium data from the EPA's UCMR 5 program (2023–2025). Lithium was detected in 23 of those cities. There is currently no federal MCL or health advisory for lithium — the state average max detected level is 17.6 µg/L. Nationally, lithium is detected in roughly 28% of sampled water systems. Lithium occurs naturally in groundwater, particularly in arid western states, and is concentrated in some surface waters near industrial discharge or geothermal sources. UCMR 5 added lithium monitoring in 2023, providing the first systematic national snapshot of public-water lithium levels. At therapeutic doses (administered as a medication), lithium is used to treat bipolar disorder. Chronic low-dose exposure from drinking water has been associated in some studies with effects on thyroid function and possibly mood. The most protective state guidance value is around 60 µg/L. Reverse osmosis and ion exchange are effective removal methods.
Cities exceeding No federal MCL or HA
Lithium data across Connecticut
Each dot is a city with UCMR 5 lithium testing data. Detected cities are shown — there is no federal limit, though some states use 60 µg/L as a screening level. Size reflects population served.
Top 10 cities by lithium level in Connecticut
Highest Lithium levels (µg/L)
All Connecticut cities ranked by lithium level
| # | City | Level | Level | Detected? | Violations | Grade |
|---|---|---|---|---|---|---|
| 1 | Hampton | 24.9 µg/L | Detected | 12 | B- | |
| 2 | Hampton | 24.9 µg/L | Detected | 1 | B | |
| 3 | Ansonia | 22.2 µg/L | Detected | 18 | F | |
| 4 | Berlin | 19.8 µg/L | Detected | 5 | C | |
| 5 | Berlin | 19.8 µg/L | Detected | 8 | C | |
| 6 | Berlin | 19.8 µg/L | Detected | 40 | F | |
| 7 | Berlin | 19.8 µg/L | Detected | 0 | B- | |
| 8 | East Granby | 19.8 µg/L | Detected | 5 | C- | |
| 9 | East Granby | 19.8 µg/L | Detected | 85 | F | |
| 10 | East Granby | 19.8 µg/L | Detected | 9 | D | |
| 11 | East Granby | 19.8 µg/L | Detected | 25 | F | |
| 12 | East Granby | 19.8 µg/L | Detected | 24 | F | |
| 13 | East Granby | 19.8 µg/L | Detected | 12 | C- | |
| 14 | East Granby | 19.8 µg/L | Detected | 1 | C+ | |
| 15 | East Granby | 19.8 µg/L | Detected | 0 | B | |
| 16 | East Granby | 15.1 µg/L | Detected | 9 | F | |
| 17 | East Granby | 15.1 µg/L | Detected | 3 | C+ | |
| 18 | Ansonia | 11.8 µg/L | Detected | 12 | F | |
| 19 | Berlin | 11.8 µg/L | Detected | 3 | D+ | |
| 20 | Berlin | 11.8 µg/L | Detected | 4 | C | |
| 21 | Bristol | 11.8 µg/L | Detected | 4 | C+ | |
| 22 | Beacon Falls | 9.2 µg/L | Detected | 27 | F | |
| 23 | Ansonia | 9.0 µg/L | Detected | 28 | F |
Frequently asked questions about lithium in Connecticut
Is lithium in Connecticut tap water harmful?
Lithium has no federal MCL or health advisory. Some state agencies use 60 µg/L as a screening level. 23 cities in Connecticut had detectable lithium in UCMR 5 testing. Therapeutic lithium doses (used to treat bipolar disorder) are far higher than typical drinking-water levels, but chronic low-level exposure has been studied for potential thyroid and mood effects.
Where does lithium in tap water come from?
Lithium occurs naturally in groundwater, especially in arid western states with lithium-bearing geology (parts of Nevada, California, North Carolina, Texas). It can also enter water from industrial sources such as battery manufacturing, ceramics, and lithium-mining wastewater. Geothermal hot springs are another natural source.
How can I remove lithium from my drinking water?
Reverse osmosis is highly effective at removing lithium, typically reducing it by 90% or more. Ion exchange systems and distillation also work well. Standard activated carbon filters are NOT effective against lithium. If you rely on a private well in a lithium-rich geological area, consider testing.