Lead in well water

Best for

Homes with older plumbing, brass fixtures, a pump installed before about 1995, a well drilled before 1993, or acidic water.

Wrong fit

If a child under six or a pregnant woman drinks the water and lead is detected, switch to bottled or certified-filtered water now, before chasing the source.

Tradeoff

Lead results swing from sample to sample, so one clean test does not prove the water is always safe, and a filter only protects the taps it is on.

Where lead in a well comes from

Lead is rarely a groundwater problem. The Minnesota Department of Health says groundwater in Minnesota usually does not contain detectable lead. Instead, lead dissolves from parts of the well and plumbing, and the longer water sits in contact with them, the more lead it picks up. Minnesota and Penn State Extension list the usual sources:

• Lead pipes, the worst contributor where they exist.
• Lead solder joining copper pipes. Minnesota notes it has been illegal there since 1985, and Penn State says copper plumbing installed before January 1991 likely has lead solder.
• Brass faucets, valves and fittings. Brass can leach lead even in homes with plastic pipe, especially when new. Since January 2014, federal law limits most new pipe, fittings and fixtures to 0.25% lead.
• Lead packers above the well screen, common in wells drilled before 1980 and used in some wells drilled until 1993, when they were prohibited.
• Submersible pumps made before 1995, some of which have leaded-brass parts. Penn State says pump brass corrosion was a source through the mid-1990s.

Water chemistry decides how much of that lead ends up in your glass. Penn State explains that acidic water (pH below 7) that is low in calcium carbonate is more corrosive, that soft water and warm water are more corrosive, and that grounding electrical systems to water pipes can increase corrosion. See acidic well water.

Is it a health risk?

Yes. The EPA says the best available science shows there is no safe level of exposure to lead, which is why its health goal for lead in drinking water is zero. Minnesota also says there is no safe level and recommends keeping lead in water as close to zero as possible.

Young children, infants and pregnant women are most at risk. The EPA says low-level exposure in children has been linked to damage to the nervous system, learning disabilities, shorter stature, impaired hearing and effects on blood cells, and that lead stored in a mother’s bones can be released during pregnancy and reach the fetus. The EPA estimates drinking water can make up 20% or more of a person’s total lead exposure, and 40 to 60% for infants who consume mostly mixed formula. Penn State notes adult effects include higher risks of kidney disease, high blood pressure and stroke.

Lead in water is a drinking risk, not a bathing one. The EPA says bathing and showering should be safe even above the action level, because skin does not absorb lead from water.

The numbers on your report

Private wells are not covered by these rules. Penn State, for example, uses 15 µg/L as the mark for concerning lead in its private-well survey, but no level is considered safe.

How to test

Lead results depend heavily on how the sample is taken. Penn State and Minnesota describe two samples:

• First-draw sample. Water that has sat in the plumbing at least 6 hours, usually first thing in the morning from the cold kitchen tap. It shows how much lead the plumbing adds.
• Flushed sample. Collected after running the cold water for a minute or two. It shows what is coming from the well, pump and main lines.

Ask the lab for total lead, which includes particles, rather than only dissolved lead; Penn State notes particulate lead can loosen during plumbing work or nearby construction. Test pH and copper at the same time, since corrosive water drives both. Use a state-certified lab. A certified-lab mail-in test such as Tap Score’s well water tests is one option; check that lead is included in the package you choose. See how to test well water.

Comparing the two samples tells you where to look. Penn State explains that metals from corrosion are highest in the first water and drop as you flush; if they do not drop, the source is more likely the well water itself.

If your result is X, do Y

Penn State recommends corrective action whenever a first-draw test shows detectable lead or you find several lead sources in your plumbing.

Ways to reduce lead

Boiling does not help; the EPA says boiling water does not remove lead.

For most well homes with a plumbing-related lead result, the practical combination is a filter certified for lead at the kitchen tap, corrosion control if pH is low, and replacement of old fixtures over time. An under-sink reverse osmosis system is one way to cover drinking and cooking water.

Maintenance and retesting

• Retest first-draw and flushed samples a few months after any fix to confirm it worked.
• Retest after replacing a pump, faucet or section of pipe; new brass can leach lead for the first months, as Minnesota notes.
• Replace filter cartridges on schedule. The EPA says an expired cartridge is less effective, and Penn State stresses following the maker’s instructions for changing it.

When to call a pro or the health department

Call a licensed well contractor if the flushed sample is high, especially if your well was drilled before 1993 or your pump predates 1995. Call your state or local health department, and your child’s doctor, if lead is detected and a child under six or a pregnant woman lives in the home. Find your state program under states.