Anthony Lacey
- Heavy metals can be harmful even at low levels in tap water.
- Lead is a heavy metal contaminant in that it comes from pipes, not polluters.
- Filters like reverse osmosis can remove some heavy metals from drinking water.
Among the many contaminants lurking in drinking water throughout the U.S., heavy metals can pose health concerns, because they’re toxic even at low levels. Millions of Americans drink tap water contaminated with these substances every day – many without knowing it.
EWG’s Tap Water Database shows which heavy metals are in your water and how to eliminate some of them. Several of these substances are prevalent coast to coast. The heavy metal manganese, for example, contaminates tap water for almost 300 million people in the U.S.
Heavy metals is a broad term that refers to a class of contaminants of concern. This group includes arsenic, hexavalent chromium, lead, manganese, mercury and more. Industrial operations, mining and other activities can increase heavy metal levels in water.
EWG’s Tap Water Database, updated earlier this year, can help you find out which heavy metals contaminate your drinking water and in what amounts. Simply enter your ZIP code into the database to get the most recent results, as reported by the local water utility. The database can even suggest which water filters might work best to reduce heavy metals in your water.
Understanding heavy metals as a class
Many water systems throughout the U.S. may be contaminated by more than one heavy metal, sometimes in alarming amounts. Here’s a snapshot of some of the most concerning heavy metals at their peak, based on data from the Tap Water Database:
Arsenic
This is a naturally occurring mineral that can be worsened by industrial and agricultural activity. It causes bladder, lung and skin cancer.
Levels of this heavy metal are exceedingly high in some parts of the U.S., with Grand Blanc, Mich., reporting it at 35.7 parts per billion, or ppb. That’s more than triple the Environmental Protection Agency’s legal limit of 10 ppb.
Hexavalent chromium
Also known as chromium-6, this cancer-causing chemical was made notorious by the film “Erin Brockovich,” which documented the poisoning of drinking water in Hinkley, Calif. It enters drinking water as pollution from industrial uses, and through the erosion of rock and soil.
There’s no EPA limit for chromium-6 in drinking water. Norman, Okla., which provides water for more than 100,000, detected chromium-6 at 39.3 ppb. That’s an astonishing 1,967 times the guideline EWG believes is necessary to protect against health harms.
Manganese
Manganese is a naturally occurring mineral found in food, drinking water and soil. In small amounts, manganese is necessary for good health. But in excess, manganese can harm infants and children. Increasingly, scientific evidence shows manganese exposures during pregnancy and childhood can impair learning, memory and behavior in children and the developing fetus.
The EPA hasn’t set a legal limit for this heavy metal in drinking water. EWG’s health guideline is set at 100 ppb to protect against harm to the brain and nervous system. Manganese has been found at much higher levels in some areas, including Pierre, S.D., where it has been detected at up to 2,500 ppb.
Mercury
This heavy metal is a potent neurotoxin that also damages the kidneys and other internal organs. Mercury enters drinking water from industrial pollution, mining waste and coal-fired power plants.
The EPA’s legal limit for inorganic mercury in tap water, established in 1991, is 2 ppb. Unlike several other heavy metals, mercury at the levels shown in the latest Tap Water Database do not typically exceed this limit.
Lead
Even at very low levels, lead exposure can cause permanent, irreversible harm to IQ and the nervous system of toddlers and children. There is no safe level of lead in blood.
Unlike other heavy metals, lead in drinking water doesn’t come from industrial and other discharges ending up in public water systems. It originates from corrosion of lead water infrastructure pipes and household service lines.
Since lead levels vary from one building to another, it is difficult to estimate how many people have lead-contaminated water in their homes and schools.
The EPA in 2024 lowered the action level for lead in drinking water from 15 to 10 ppb. That’s far higher than California Office of Health Hazard Assessment’s public health goal of 0.2 ppb. EWG urges the federal government to set a more-protective legal limit for lead.
Reducing your exposure to heavy metals
If you search EWG’s Tap Water Database for your location and find that one or more heavy metals have been detected by your water system, you may want ways to lower your exposure.
The database provides information specific to your ZIP code about potential options for filtering your water, including countertop water filters and other selections.
Filters aren’t a one-size-fits-all solution for heavy metal contamination. Some filters may not be able to reduce or remove all the heavy metals in your tap water, but they can help to lower your overall exposure to certain contaminants.
Toxic metals don’t belong in your drinking water, especially when we know how to detect and reduce them. Concerned about your water? Demand stronger regulations from your local representatives and government funding to replace aging infrastructure such as lead pipes.
With the right tools, you can take steps to protect your health and advocate for cleaner water for your community.
May 2025