Lead
The parameter where the water leaving the treatment plant tells you nothing, because the lead comes from your own pipes.
- Safe range
- 0 – 0.015 mg/L (US EPA action level; health goal is zero)
- Ideal range
- 0 mg/L
- Measured in
- mg/L
What it is
Lead is almost never in the source water. It dissolves into water from the plumbing it sits in: lead service lines, lead solder in copper joints, and the brass in taps and valves. That is why it is the one parameter your utility's report cannot answer for you: two houses on the same street, fed by the same main, can give completely different results.
Why it matters
EPA sets no maximum contaminant level for lead. It sets a maximum contaminant level GOAL of zero, because no level of lead is known to be safe, and an action level of 0.015 mg/L (15 ppb) that obliges a water system to act on corrosion control and service lines. The action level is a 90th percentile across a system's sampled taps, not a verdict on any single house, and it is the number a laboratory report will be read against. Lead is a developmental neurotoxin: children under six and pregnancy are where the risk is concentrated, and the effects are cumulative rather than acute, so there is no symptom to wait for.
How to measure it
A certified laboratory, and nothing else. This is the one parameter on this site where a home kit is not a cheaper answer but a different and unreliable one: the concentrations that matter are far below what a colour change can resolve.
Certified laboratory, mail-in kit
- How trustworthy
- Reference grade
- Cost
- Most expensive
- Effort
- Careful sampling, then days or weeks of waiting
You are posted bottles and instructions, you fill them exactly as told, and you post them back. Weeks later a report arrives with figures nobody has to interpret by eye. This is what a result you intend to act on should be built from.
Bottles, precise instructions, and a result in parts per billion from an instrument. Ask your water utility and your local health department first: many run free or subsidised lead testing, particularly for households with young children or a known lead service line.
Watch out: Follow the sampling instructions exactly, including which tap and how long the water must have stood. A lead sample taken the wrong way is not a conservative result; it is usually a falsely reassuring one.
Where to find it: State-certified drinking water laboratories; your state's certification officer keeps the list, and many public health departments will point you at one.
Your utility's annual water quality report
- How trustworthy
- Reference grade
- Cost
- Free
- Effort
- A few minutes of reading
Every community water system in the US has to publish one each year, free, listing what it found and what the limits are. It is real laboratory data about the water leaving the plant and travelling the mains. What it cannot describe is your own plumbing.
Says how the system as a whole performed and is required to tell you about lead service lines. Utilities now have to keep an inventory of service line materials, and many publish a lookup by address, which is worth checking before you spend anything.
Watch out: The figure published is a percentile across sampled homes, not a measurement of your tap. Two houses on one street can differ completely, so a good report proves nothing about your own kitchen.
Where to find it: Your water bill, your supplier's website, or the EPA's index of reports. It is also called a Consumer Confidence Report or CCR.
Test strips
- How trustworthy
- Ballpark
- Cost
- Low cost
- Effort
- Under a minute, wherever you drew the sample
A plastic strip with reagent pads on it. Dip it, hold it level, and match each pad against the chart on the bottle at the time the label tells you to. Most strips read several parameters at once.
Sold as instant lead tests, and listed here because they are easy to find and easy to trust wrongly. A non-detect on a strip is not evidence that there is no lead.
Watch out: Treat a positive as a reason to call a laboratory and a negative as no information at all. Nothing about a home lead result should change what you give an infant.
Where to find it: Pool shops, hardware stores, supermarkets and online, sold both per parameter and as multi-packs. Buy strips made for your kind of water: pool strips and drinking water strips read very different scales for the same chemistry.
Taking the sample
For several of these the sample is where the error is, and no instrument recovers from a bad one.
- • The sample that matters is the FIRST water out of the tap after it has stood still, usually overnight or at least six hours. Lead accumulates while water sits in the pipe, so flushing before you sample measures the main rather than your plumbing.
- • Do not clean or remove the aerator before sampling unless the laboratory tells you to. What has collected there is part of what you are trying to detect.
- • If the question is whether running the tap helps, take two samples: one first draw and one after the water has run cold, and let the pair answer it.
Further reading: US EPA: basic information about lead in drinking water; US EPA: certified drinking water laboratories, by state
If it is too low
Lead below what the test can report. This is the result you want; unlike most parameters here, there is no benefit to any amount of it.
- • Nothing to act on. Retest if you replace plumbing, or if work is done on the water main in your street; disturbing a service line is a classic cause of a sudden spike.
If it is too high
Any detectable lead is worth acting on, and above the 15 ppb action level it is worth acting on immediately. Boiling does not help and makes it slightly worse: the water evaporates and the lead stays behind.
- • Do not use hot tap water for drinking, cooking or infant formula; hot water dissolves lead faster. Do not boil it.
- • Run the tap until it is noticeably colder before drawing water to drink, especially first thing in the morning. Lead accumulates while water sits still in the pipe.
- • Confirm with a certified laboratory test before acting on a home result, and ask your water utility whether your property is on a lead service line; they are required to keep an inventory.
- • If you filter, use one certified to NSF/ANSI 53 for lead reduction. A standard carbon taste-and-odour filter is not that, and replacing the cartridge on schedule is part of the certification.
Common questions
What is the safe level of lead in drinking water?
There is no safe level, and EPA says so directly: the maximum contaminant level goal for lead is zero. What EPA does set is an action level of 15 ppb, which is a trigger for the water system to act rather than a line between safe and unsafe water at your tap. Treat any detectable lead as worth reducing.
Why does my neighbour's result differ from mine?
Because the lead is coming from the plumbing rather than the water. Whether your property has a lead service line, lead solder or brass fittings, how long the water has been standing, and how corrosive the water is all change the answer house by house. This is the parameter your utility's annual report genuinely cannot answer for you.
Does boiling water remove lead?
No, and it slightly concentrates it. Boiling drives off water and leaves the lead behind. Removing lead needs a filter certified to NSF/ANSI 53 for lead, reverse osmosis, or distillation.
Is the 15 ppb action level changing?
EPA has finalised the Lead and Copper Rule Improvements, which lower the action level to 10 ppb and require lead service lines to be replaced. Systems have until the rule's compliance dates to meet it, so a report you read today is still being measured against 15 ppb.
WiseWaterGauge helps you record and understand your own readings. It is not a substitute for a certified laboratory test, and nothing here is medical or regulatory advice. If a health parameter is out of range, confirm it with an accredited lab and speak to your water provider.