Domestic groundwater wells in the eastern and southeastern U.S. at risk of lead contamination

Release Date:

About one-third of more than 8,300 wells tested across the U.S. had groundwater with chemical characteristics that could cause lead, if present in plumbing, to leach into tap water at levels above the EPA Action Level, according to a new study by the U.S. Geological Survey National Water Quality Program. These characteristics are most common in groundwater in the East and Southeast.

Lead can dissolve into water if the water corrodes a lead-containing material such as lead pipes, lead solder, or brass fittings. The USGS study used measured chemical characteristics of groundwater from more than 8,300 wells tapping groundwater to estimate the potential solubility of lead for each sample. Groundwater with low pH, low alkalinity, and/or low phosphate concentrations had the greatest lead solubility potentials.

Nationwide, about 33% of untreated groundwater samples had the potential to dissolve 15 micrograms per liter or more of lead, the U.S. Environmental Protection Agency Action Level for lead in treated water from public drinking water supplies, and 5% had the potential to dissolve 300 micrograms per liter or more of lead. The states with the greatest percentage of wells producing untreated groundwater with a high lead solubility potential (300 micrograms per liter or greater) were Maryland, New Jersey, Delaware, Tennessee, and Arkansas. Lead is a toxic metal that can be harmful to human health even at low exposure levels.

Map showing lead potential solubility of untreated groundwater

Lead can dissolve into water if the water corrodes a lead-containing material such as lead pipes, lead solder, or brass fittings. Groundwater chemistry gives an indication of where that is most likely to happen at high concentrations.

 

In the U.S., groundwater at the wellhead is rarely a source of high lead concentrations in drinking water; rather, the source of the lead typically is somewhere in the plumbing system. Less than 1% of the more than 8,300 untreated groundwater samples evaluated contained dissolved lead at a concentration greater than the U.S. EPA action level of 15 micrograms per liter.

Potentially corrosive groundwater can be treated to minimize the leaching of lead into drinking water, and such treatment is required for public-water supplies to prevent corrosion of lead-bearing materials if the water at customer taps contains lead. However, lead testing and corrosion treatment for domestic wells are not required by federal law or by most states. Households that drink self-supplied (domestic well) water therefore can be at greater risk of consuming water that contains lead than households that rely on public-water supplies.

For more information about the study, contact Bryant Jurgens (bjurgens@usgs.gov).

Citation: Jurgens, B.C., Parkhurst, D.L., and Belitz, K. 2019. Assessing the lead solubility potential of untreated groundwater of the United States. Environmental Science and Technology. https://doi.org/10.1021/acs.est.8b04475

Related Content

Filter Total Items: 3
Date published: March 1, 2019
Status: Active

Metals and Other Trace Elements

Metals, metalloids, and radionuclides all are trace elements that occur naturally in the Earth's crust. In small quantities many trace elements are essential for health in all living organisms, but some trace elements can be toxic or cause cancer, and some can bioaccumulate. The USGS investigates where and how trace elements make their way into our Nation's surface water and groundwater.

Attribution: Water Resources
Date published: March 1, 2019
Status: Active

Corrosivity

Corrosivity describes how aggressive water is at corroding pipes and fixtures. Corrosive water can cause lead and copper in pipes to leach into drinking water and can eventually cause leaks in plumbing.  Surface water and groundwater, both sources of drinking water, can potentially be corrosive.

Contacts: Ken Belitz
Date published: February 28, 2019
Status: Active

Groundwater Quality—Current Conditions and Changes Through Time

Is groundwater the source of your drinking water? The USGS is assessing the quality of groundwater used for public supply using newly collected data along with existing water-quality data. Learn more about this invisible, vital resource so many of us depend on.

Contacts: Bruce Lindsey