Lead is one of the few contaminants that usually has nothing to do with your city's water source or its treatment plant. It gets into tap water on the last stretch of the journey — the pipes, solder and fixtures between the water main and your faucet. That single fact explains why lead is measured differently from almost everything else, and why a citywide water report can look clean while one house on the street tests high.
Where lead in drinking water actually comes from
Water leaving a treatment plant is essentially lead-free. Lead enters afterwards, by corrosion, from four main places:
- Lead service lines — the pipe connecting the water main to the building. These are the largest single source. Millions are still in use across the United States, concentrated in housing built before the mid-1980s.
- Lead solder used to join copper pipes. Lead solder was banned for drinking water plumbing in 1986, so homes plumbed before then are most likely to have it.
- Brass and bronze fixtures — faucets, valves and fittings. Brass can contain lead even when sold as “lead free.”
- Galvanized pipe that sat downstream of a lead line and absorbed lead over time.
How much lead ends up in the water depends on how corrosive the water is, how long it sits in the pipe, and the water's temperature. Water that has been sitting overnight in a lead service line carries far more lead than water drawn after the tap has been running.
Why there is no meaningful “cities with the most lead” ranking
Most contaminants — PFAS, nitrate, arsenic, disinfection byproducts — are measured in the water a utility delivers, so you can compare one system against another. Lead is different. Because the source is your building's plumbing, utilities sample at a set of customer taps rather than at the plant, and results vary house by house within the same system.
The practical consequence: a citywide average tells you very little about your own kitchen. The only number that describes your water is a sample taken from your own tap. If you want to see what is measured system-wide where you live, our water quality database covers contaminants reported at the treatment and distribution level, including PFAS.
What the regulations require
Under the Safe Drinking Water Act, the EPA sets the maximum contaminant level goal for lead at zero — there is no level identified as safe. Because lead comes from plumbing rather than the source, it is regulated through treatment technique rather than a simple limit.
- Action level. Under the Lead and Copper Rule, if more than 10% of sampled taps exceed 15 parts per billion, the utility must act — adjust corrosion control, notify customers and begin replacing lead lines.
- The 2024 update. The EPA finalized the Lead and Copper Rule Improvements in October 2024, which lowers the action level to 10 ppb and requires water systems to replace lead service lines, with most systems working to a ten-year timeline.
- Service line inventories. Utilities are required to publish an inventory of service line materials. Many now have a lookup tool where you can check your own address.
- “Lead free” is not zero lead. Since 2014 the legal definition allows up to 0.25% lead in the wetted surfaces of pipes and fittings.
Health effects
Lead accumulates in the body over time, and public health agencies treat any exposure as undesirable rather than setting a safe threshold. The CDC states there is no known safe blood lead level in children.
- Infants and children absorb lead more readily than adults. The EPA associates childhood exposure with effects on cognitive development, attention and academic performance.
- During pregnancy, lead stored in bone can be released into the bloodstream and reach the fetus.
- Adults face cardiovascular effects including increased blood pressure, along with kidney effects at higher exposures.
Formula-fed infants are a particular concern because powdered formula is mixed with tap water, so the water is a large share of total intake.
How to find out whether your water has lead
You cannot see, taste or smell lead in water, and there is no way to infer it from your water's appearance. There are three things worth doing:
- Check your service line. Look up your address in your utility's service line inventory. You can also inspect the pipe where it enters the building: unpainted lead is dull grey, scratches to a shiny silver, and is not magnetic.
- Read your utility's Consumer Confidence Report. It reports the 90th-percentile tap result for the system and whether the action level was exceeded. This describes the system, not your house.
- Test your own tap. This is the only way to know your number. Many utilities provide free or subsidized kits; otherwise use a state-certified laboratory. Collect a first-draw sample after water has sat in the pipes for at least six hours, following the lab's instructions exactly.
How to reduce lead at the tap
Two clarifications first, because both are widely misunderstood:
- Boiling does not remove lead. Boiling evaporates water and concentrates the lead that remains.
- Not every filter removes lead. A filter reduces only what it is certified to reduce. Look for certification, not marketing language.
Practical steps:
- Flush before use. After water has been sitting for hours, run the cold tap until it turns noticeably colder before drinking or cooking with it.
- Use cold water. Hot water dissolves lead more readily. Never use hot tap water for drinking, cooking or mixing formula.
- Clean your aerators. Particles of lead-bearing scale collect in the faucet screen.
- Use a filter certified for lead. Point-of-use filters certified to NSF/ANSI 53 for lead reduction and reverse osmosis systems certified to NSF/ANSI 58 are the two standards to look for. Check the specific certification for the model you are considering, and replace cartridges on schedule — an exhausted filter stops performing.
- Replace the line. Filtration treats the water at one tap; replacing a lead service line removes the source. Many utilities now cost-share replacement.
If you are comparing treatment options for your home, our water filtration systems include reverse osmosis, and you can look up your local water quality report to see what else has been detected in your area.
The short version
Lead is a plumbing problem, not a water source problem. Your city's report cannot tell you your number, so find out whether you have a lead service line, test your own tap, use cold water and a filter certified for lead in the meantime, and treat replacing the line as the real fix.
Sources: US EPA (Safe Drinking Water Act, Lead and Copper Rule, Lead and Copper Rule Improvements 2024), Centers for Disease Control and Prevention, NSF/ANSI standards 53 and 58.
