Short entry

Thallium in drinking water

Also listed as Tl

We haven’t published a full explainer for Thallium yet, so this page only shows what we can stand behind and where to go next.

This page can’t tell you what’s in your tap water.

Only a test of water from your own tap can. Public-system results describe the system, not your home.

Reference values

A legal limit — and a lower health goal.

Enforceable limit · MCLFederal · public water systems

2 ppb

The highest level allowed in water a public system delivers. A legal limit, not a health goal.

Health-based goal · MCLGFederal · not enforceable

0.5 ppb

The level below which no known health risk is expected. A goal, not a limit.

Applies to: Set alongside the rule as a public-health goal
Status: Published goal
Source: EPA National Primary Drinking Water Regulations — MCLG 0.0005 mg/L · 40 CFR §141.51

How they relate

Health-based goalNo known risk expected below itEnforceable limitThe legal maximum

Water between the two isn’t automatically safe. A goal and a legal limit answer different questions. Positions are illustrative, not to scale.

Your stateNot held yetStates may set their own references. We don’t hold a state reference for thallium yet.

Is it in my water?

Start with the tool that matches your water source.

Treatment

We don’t hold treatment evidence for Thallium yet, so we don’t describe methods or show products on this page.

References

40 CFR §141.62 · EPA NPDWR MCL (0.002 mg/L)
40 CFR §141.51 · EPA National Primary Drinking Water Regulations — MCLG 0.0005 mg/L