Toxic Heavy Metals You Should Check For in Your Water
The main heavy metals in drinking water include lead, arsenic, chromium, cadmium, mercury, copper, nickel, and manganese. These contaminants can enter water through natural mineral deposits, industrial pollution, and corroding plumbing. Many are colorless, odorless, and tasteless, making laboratory testing necessary to measure their concentrations.
How Heavy Metals Get Into Drinking Water
Common sources of heavy metals in drinking water include:
- Corroding plumbing: Older pipes, lead solder, and brass fixtures can release metals into water.
- Natural deposits: Minerals in rocks and soil can release arsenic, chromium, and manganese into groundwater.
- Industrial waste: Contaminants from industrial activities can enter groundwater and surface water.
- Property runoff: Runoff carrying contaminants associated with paints, batteries, and certain agricultural or industrial activities can affect water sources.
- Galvanized pipes: Corrosion of older galvanized plumbing can contribute to metal contamination.
A potential source points to possible contamination. Laboratory testing helps determine which metals are present and whether their concentrations exceed applicable standards.
Drinking Water Limits for Heavy Metals: Federal and California
Selected federal and California standards come from the EPA’s federal drinking water regulations and California’s chemical contaminant standards.
| Metal | Federal limit (µg/L) | California limit | Type |
|---|---|---|---|
| Antimony | 6 | 6 µg/L | MCL |
| Arsenic | 10 | 10 µg/L | MCL |
| Barium | 2,000 | 1,000 µg/L | MCL |
| Beryllium | 4 | 4 µg/L | MCL |
| Cadmium | 5 | 5 µg/L | MCL |
| Total chromium | 100 | 50 µg/L | MCL |
| Hexavalent chromium (Cr VI) | No separate federal MCL | 10 µg/L | California MCL |
| Copper | 1,300 | 1,300 µg/L | Action level |
| Lead | 15; scheduled to become 10 on November 1, 2027 | 15 µg/L | Action level |
| Manganese | 50 | 50 µg/L | Secondary standard |
| Mercury (inorganic) | 2 | 2 µg/L | MCL |
| Nickel | No federal MCL | 100 µg/L | California MCL |
| Selenium | 50 | 50 µg/L | MCL |
| Thallium | 2 | 2 µg/L | MCL |
| Uranium | 30 | 20 pCi/L | MCL; different units |
A maximum contaminant level (MCL) is an enforceable drinking water standard for public water systems. An action level triggers specified regulatory requirements when monitoring results meet applicable conditions. A secondary standard addresses aesthetic concerns, such as taste and color.
California has stricter standards for certain contaminants, including total chromium. The federal lead action level is scheduled to decrease to 10 µg/L on November 1, 2027, under the Lead and Copper Rule Improvements. The EPA’s drinking water standards and California’s official drinking water regulations provide further details.
List of Toxic Heavy Metals in Drinking Water
Arsenic
Limit: 10 µg/L under federal and California regulations.
Arsenic can enter groundwater through natural mineral deposits and contaminated runoff. Long-term exposure above the drinking water standard can cause skin damage, circulatory problems, and an increased risk of cancer. Private well owners should arrange regular testing based on their water source and local conditions.
Barium
Limit: Federal MCL of 2,000 µg/L; California MCL of 1,000 µg/L.
Barium occurs naturally in some rocks and minerals and can enter groundwater. Elevated exposure can affect health, so testing is useful where local geology or other conditions indicate a potential risk.
Cadmium
Limit: 5 µg/L under federal and California regulations.
Cadmium can enter water through natural deposits, contaminated runoff, and corroding galvanized plumbing. Elevated exposure can cause kidney damage. Testing helps determine whether concentrations exceed the applicable standard.
Chromium
Limits: Federal total chromium, 100 µg/L; California total chromium, 50 µg/L; California chromium-6, 10 µg/L.
Chromium-3 and hexavalent chromium, or chromium-6 (Cr VI), are different chemical forms. Chromium can enter water through natural deposits and industrial contamination. Chromium-6 is associated with cancer concerns, while chromium exposure can also cause allergic skin reactions.
California’s separate chromium-6 drinking water standard took effect on October 1, 2024. Compliance dates vary by public water system size.
Copper
Limit: 1,300 µg/L action level.
Copper commonly enters drinking water through corroding household plumbing. Blue-green staining can indicate corrosion, and testing measures the actual concentration. Elevated exposure may cause stomach and intestinal distress.
Lead
Limit: Federal action level of 15 µg/L, scheduled to decrease to 10 µg/L on November 1, 2027. The EPA’s health goal is zero.
Lead may enter water through lead service lines, solder, and older brass fixtures. No level of lead exposure is known to be safe. Exposure can affect children’s development and contribute to health problems in adults.
The action level is a regulatory trigger that requires water systems to take specified steps.
Manganese
Limit: 50 µg/L secondary standard.
Manganese occurs naturally in soil and rock and can enter groundwater. Elevated concentrations may cause black staining and affect taste or color. High exposure can also affect the nervous system.
Mercury
Limit: 2 µg/L for inorganic mercury.
Mercury can enter water through natural deposits, contaminated runoff, and industrial discharges. Elevated exposure to inorganic mercury can damage the kidneys. The chemical form matters when evaluating potential health effects.
Nickel
Limit: No federal MCL; California MCL of 100 µg/L.
Nickel can occur naturally in groundwater or enter water through industrial discharges and contact with certain metal fixtures. Exposure can cause allergic skin reactions in sensitive individuals.
Other Regulated Metals
Antimony, beryllium, selenium, thallium, and uranium also have drinking water standards. Their limits appear in the drinking water limits table. Uranium is measured in different units under federal and California standards, so direct numerical comparisons are inappropriate.
Which Water Supplies Should Be Tested for Heavy Metals?
Consider testing in the following situations:
- Private and business wells: Owners are responsible for arranging testing.
- Older buildings: Lead pipes, solder, and older brass fixtures may contribute to contamination.
- Schools and childcare facilities: Water quality assessment is important because children are particularly vulnerable to lead exposure.
- New or changed supplies: New wells, water connections, and plumbing work may warrant testing.
- Areas with elevated groundwater arsenic: Local geology can influence which contaminants need assessment.
These conditions raise the chance of contamination, and testing provides the evidence to guide further investigation.
Heavy Metals in Workplace Drinking Water
Employees and visitors may drink workplace water or use it to prepare food and beverages. Older buildings, aging plumbing, and business wells can warrant closer attention.
Potential sources include lead solder, old pipes, and runoff carrying contaminants associated with agricultural or industrial activities.
Testing before purchasing a treatment system helps identify the metals present and whether their concentrations exceed applicable standards. Results can guide the selection of appropriate treatment options.
Learn more about drinking water testing.
How Heavy Metals in Water Are Detected
Most dissolved metals are invisible, odorless, and tasteless. Test strips can screen for certain metals, and laboratory analysis provides measurements that can be compared with applicable standards.
Torrent Laboratory’s guide on how to test water for heavy metals covers sampling, analysis, and reading results.
Heavy Metal Testing at Torrent Laboratory
Torrent Laboratory provides laboratory testing to help clients assess metals in drinking water and well water. The appropriate testing scope depends on the water source and the contaminants that need to be evaluated.
Contact the laboratory to discuss your testing requirements or learn more about heavy metal water testing.
Frequently Asked Questions
Q1. What heavy metals are found in drinking water?
Common metals include lead, arsenic, chromium, cadmium, mercury, copper, nickel, and manganese. Other regulated contaminants include antimony, barium, beryllium, selenium, thallium, and uranium.
Q2. What is the safe level of lead in drinking water?
No level of lead exposure is known to be safe. The EPA’s health goal is zero. The current federal action level is 15 µg/L, scheduled to decrease to 10 µg/L on November 1, 2027.
Q3. Does California have stricter drinking water limits than the EPA?
Yes. California has stricter limits for certain contaminants, including total chromium. It also has a separate chromium-6 standard and a nickel MCL.
Q4. Should well water be tested for heavy metals?
Yes. Private well owners are responsible for arranging testing, because federal rules for public water systems exclude private wells. Local groundwater conditions can make arsenic and manganese important contaminants to assess.
Q5. What is chromium-6?
Chromium-6, or hexavalent chromium (Cr VI), is a form of chromium associated with cancer concerns. California established a separate drinking water MCL of 10 µg/L, effective October 1, 2024.
Q6. Can heavy metals be removed from drinking water?
Yes. Treatment options depend on the metals present, their concentrations, and the water’s characteristics. Testing first helps identify the contaminants that need to be addressed.
Contact Torrent Laboratory
Understanding which metals are present helps property owners and businesses make informed water quality decisions. Contact Torrent Laboratory to discuss your testing needs, request a quote, or learn about Torrent Express sample pickup.
