Lithium in Drinking Water: Health Effects, UCMR 5 Data & Removal

What Is Lithium?

Lithium is a naturally occurring alkali metal found in groundwater across much of the western and southwestern United States. It is also the active ingredient in a class of mood-stabilizing medications used to treat bipolar disorder. Most people associate lithium with batteries and pharmaceuticals — but it has been present in trace amounts in tap water for as long as humans have drawn from groundwater.

The EPA added lithium to the Unregulated Contaminant Monitoring Rule 5 (UCMR 5, 2023–2025), which produced the first systematic national snapshot of lithium occurrence in public drinking water. The result was striking: lithium was detected in approximately 28% of large public water systems sampled — making it one of the most frequently detected analytes in UCMR 5, well above the detection rates for most regulated PFAS compounds. See the UCMR 5 PFAS monitoring results for the parallel PFAS findings from the same dataset.

How Lithium Gets Into Drinking Water

Lithium enters drinking water primarily through natural geological processes:

• Groundwater dissolution from lithium-bearing rock — particularly granite, pegmatite, and certain clay deposits in the western US (Nevada, California, Arizona, Texas, North Carolina, Wyoming)
• Geothermal sources — hot springs and geothermal aquifers carry elevated lithium
• Industrial sources (less common) — lithium battery manufacturing (which can also leach cobalt into nearby water), ceramics, glass production, and lithium mining wastewater
• Saline groundwater — areas with naturally saline aquifers tend to have higher lithium

Because lithium is highly soluble and not bound by typical sediment chemistry, once it enters groundwater it tends to stay dissolved and mobile. Surface-water systems generally show lower lithium than groundwater systems.

EPA Standards and State Guidance

There is currently no federal MCL or formal health advisory for lithium. The EPA’s UCMR 5 monitoring is purely occurrence data — no regulatory action has been proposed as of 2026.

Some state and regional agencies have set their own guidance:

• Some state screening levels: approximately 60 µg/L (often cited as a precautionary threshold)
• EPA Reference Dose (provisional): under review based on UCMR 5 results
• WHO: no formal drinking-water guideline

WaterVerge flags any detection of lithium on city pages, since the absence of formal limits means even modest concentrations are worth surfacing for awareness.

Health Effects

Lithium has a complex health profile because the same substance is a medication and an environmental contaminant. The key distinctions:

Therapeutic doses (medical use):

• Bipolar disorder treatment uses 600–1,800 mg/day (i.e., 600,000–1,800,000 µg) under medical supervision with regular blood monitoring
• These doses are 1,000–10,000× higher than what one would receive from drinking-water exposure

Drinking-water exposures:

• Thyroid effects — chronic low-dose lithium can subtly reduce thyroid hormone production. Several epidemiological studies have looked at this with mixed results.
• Mood and behavior — some controversial ecological studies have suggested associations between higher water-lithium areas and lower suicide rates, but causation is not established and results vary across regions.
• Pregnancy concerns — therapeutic lithium use during pregnancy is associated with cardiac development risks (Ebstein’s anomaly). Drinking-water levels are far below therapeutic doses, but pregnant women on therapeutic lithium should avoid additional water-borne exposure.
• Renal effects — chronic high-dose therapeutic lithium can affect kidney function. Drinking-water-level exposure has not been clearly linked to renal outcomes.

The overall picture: at typical drinking-water levels (most detections in UCMR 5 were below 100 µg/L), lithium exposure is generally considered low-risk for most adults. The populations most worth attention are pregnant women, infants, and individuals with thyroid conditions or those already on lithium medication.

How to Remove Lithium

Lithium is small, highly soluble, and does not bind to most filter media — making it one of the more difficult metals to remove with common filters:

• Reverse osmosis (RO) — typically 85–95% reduction; the most reliable household option
• Distillation — fully effective
• Ion exchange — works with appropriate resin, though standard water softeners may have limited effect at typical lithium concentrations

Standard activated carbon filters (pitchers, faucet-mount, refrigerator filters) are not effective against lithium. Boiling does not remove lithium and may concentrate it as water evaporates.

If your tap water is sourced from a groundwater system in a known lithium region (much of Nevada, parts of California, Texas, Arizona, North Carolina), an RO system is the most practical way to substantially reduce lithium intake — see the best reverse osmosis systems. Pregnant women and women on therapeutic lithium should review the pregnancy water-quality guide for added context.

What UCMR 5 Tells Us

UCMR 5 (2023–2025) gives us a baseline for national lithium occurrence:

• 28% of systems had detectable lithium
• The highest concentrations clustered in arid western states
• Most detections were in the 5–60 µg/L range; a small fraction exceeded 100 µg/L
• Surface-water systems generally showed lower lithium than groundwater systems

This data will inform any future EPA decision on whether to formally regulate lithium under the Safe Drinking Water Act.

Frequently Asked Questions

Is the lithium in tap water the same as lithium medication? Chemically yes — both are lithium ions (Li⁺). The difference is dose: therapeutic doses are 1,000–10,000× higher than drinking-water exposure.

Does lithium in water give health benefits? Some ecological studies suggested lower suicide rates in high-lithium-water areas, but the evidence is observational and disputed. There is no medical recommendation to seek out lithium-rich water.

Should pregnant women avoid lithium in tap water? Drinking-water lithium is generally far below clinically relevant levels, but cautious avoidance via filtered water (RO) is reasonable for women already on therapeutic lithium or with known thyroid conditions.