Lead in well water: where it comes from and how to reduce it

When people think of lead in drinking water, they usually picture old city water mains. Private well owners can face lead too. It usually comes from the home's own plumbing, and it's worse when well water is naturally corrosive. This guide explains how lead gets into well water, who's most at risk, how to test, and what to do about a high result.

There is no safe level

EPA and CDC agree that there is no known safe level of lead in a child's blood. EPA has set the maximum contaminant level goal (MCLG) for lead at zero, because lead is toxic even at low exposure levels and builds up in the body over time. EPA estimates that drinking water can make up 20 percent or more of a person's total lead exposure. For infants who mostly drink formula mixed with water, it can be 40 to 60 percent.

How lead gets into well water

EPA explains that lead enters drinking water when plumbing materials containing lead corrode, especially where water is acidic or low in minerals. The most common sources are:

• lead pipes, more likely in homes built before 1986;
• brass or chrome-plated brass faucets and fittings;
• lead solder on copper pipes;
• in older well systems, some pump components and fittings.

The aquifer itself is rarely the main source. That's why lead can show up at one tap and not another, or in water that has sat in the pipes overnight.

EPA lists the factors that affect how much lead dissolves: water chemistry (acidity and alkalinity), the minerals in the water, how much lead the water touches, water temperature, wear in the pipes, how long water sits, and whether protective scale has formed inside the plumbing.

Why private wells need extra attention

Public water systems must control corrosion under EPA's Lead and Copper Rule. Private wells get no such treatment. If your well water has a low pH, it can dissolve lead and copper from plumbing. EPA's well-testing chart recommends testing for pH, lead and copper if household plumbing contains lead, and for corrosion, pH and lead if pipes show signs of corrosion. CDC recommends testing pH every year. Low pH is often the first clue.

Signs of corrosive water include blue-green stains in sinks and tubs (from copper), pinhole leaks in copper pipes, and a metallic taste.

Health effects

EPA lists the effects of lead exposure:

• Children: behavior and learning problems, lower IQ and hyperactivity, slowed growth, hearing problems and anemia. In rare cases, lead ingestion can cause seizures, coma and even death.
• Pregnancy: lead stored in bones can be released during pregnancy and can cross the placenta, risking reduced fetal growth and premature birth.
• Adults: cardiovascular effects, higher blood pressure, decreased kidney function and reproductive problems.

CDC recommends public health action when a child's blood lead level is 3.5 micrograms per deciliter or more. Talk to your pediatrician about blood lead testing if you're concerned.

How to test

EPA says testing is the only sure way to know whether lead is in your water, since you can't see, taste or smell it. EPA puts typical testing costs at $20 to $100.

• Use a certified lab. Your state or local drinking water program can provide a list.
• Take a "first draw" sample of water that has sat in the pipes for several hours, such as first thing in the morning, to capture worst-case levels.
• Consider a second, flushed sample to see whether the lead comes from fixtures near the tap or from farther back in the system.
• Test pH and copper at the same time.

Reducing lead right away

EPA recommends these steps:

• Use a certified filter. Choose a filter certified to remove lead, install it correctly, replace cartridges on schedule, and don't run hot water through it.
• Clean faucet aerators regularly, because lead particles can collect there.
• Use only cold water for drinking, cooking and making baby formula.
• Remember that boiling doesn't remove lead.
• Run the water after it has sat in the pipes, by running the tap, showering or doing laundry, before drinking.

Longer-term fixes

• Neutralize corrosive water. A neutralizing filter or chemical feed can raise pH and reduce lead and copper leaching. See iron, manganese and hard water for related treatment.
• Replace lead-containing fixtures. Federal law now limits "lead-free" plumbing to a weighted average of 0.25 percent lead on wetted surfaces and 0.2 percent for solder and flux. Look for lead-free certification marks.
• Replace lead pipe or old solder joints where practical.
• Retest after changes to confirm improvement.

Buying a home with a well

If you're buying an older home with a private well, add lead, copper and pH to the water test along with the usual coliform and nitrate. Look at the visible plumbing too. Dull gray pipe that scratches to a shiny silver may be lead. Blue-green staining suggests corrosive water. If results are high, negotiate repairs or treatment before closing. See buying a house with septic and well.

Frequently asked questions

Does a water softener remove lead? Softeners aren't designed for lead. Use a filter certified for lead reduction.

How often should I test for lead? Test once to establish a baseline, then again after any plumbing changes, after installing treatment, or if your pH results change.

Can I shower?

EPA says bathing and showering should be safe for adults and children even when water contains lead above EPA's action level, because human skin doesn't absorb lead in water.

Key takeaways

• Lead in well water usually comes from plumbing, and corrosive water makes it worse.
• There's no known safe blood lead level for children.
• Test lead, copper and pH, using a first-draw sample.
• Use a certified filter and cold water for drinking, and fix corrosion at the source.
• Ask your pediatrician about blood lead testing if you have young children.