How to read your school’s lead test results — and what to do if the numbers are high

Published by NJ Clean Stream  |  Lead in Schools Series, Article 2 of 3

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Understanding the testing protocol: first-draw sampling

The standard testing protocol required in New Jersey schools is called first-draw sampling. Understanding how it works is essential to interpreting results correctly, because it captures a specific exposure scenario and will miss others.

First-draw sampling works like this: water is collected from a fixture after it has been stagnant for a minimum of six hours, without flushing the water beforehand. The sample is the first 250 milliliters — roughly one cup — that flow when the fixture is opened.

This protocol captures the worst-case scenario: the first drink from a fountain that has sat unused all night, when lead has had maximum opportunity to leach from whatever lead-containing materials are present. If a fountain shows elevated lead at first draw, children who use it first thing in the morning are genuinely being exposed at those levels. The same fountain might show dramatically lower levels after 30 seconds of flushing — but that flushed water is not what a child drinks when they arrive at school at 7:45 AM.

Some testing protocols also collect “sequential” samples — a series of 250-milliliter samples collected consecutively — to identify where in the plumbing the lead is coming from. If the highest level appears in the first sample and drops rapidly, the source is likely the fixture itself. If levels remain elevated across multiple samples, the source is deeper in the plumbing. This distinction matters enormously for remediation.

Reading the numbers: what parts per billion means

Lead in water is measured in micrograms per liter, equivalent to parts per billion (ppb). One part per billion is one microgram of lead in one liter of water — an extraordinarily small concentration that nonetheless carries real health implications for children.

New Jersey’s action level: 15 ppb. Any first-draw sample at or above 15 ppb triggers mandatory action. The outlet must be taken out of service immediately and cannot be returned to use until remediation and confirmatory testing show results below the action level.

What 15 ppb actually means for health. It is not a safe level. It is not a level below which lead causes no harm. It is an engineering benchmark set in 1991. The American Academy of Pediatrics recommends remediating any fixture above 1 ppb and establishing a goal of zero detectable lead. A result of 14 ppb is not safe. A result of 8 ppb is not safe. A result of 3 ppb is not safe.

Zero or non-detect results. When a result is reported as “ND,” “0,” or below the laboratory’s detection limit, no lead was detected at a measurable level. This is the best possible result, though it does not mean the water contains absolutely no lead — only less than the test can detect.

Results between 1 and 15 ppb. This is the gray zone the current regulatory framework largely ignores. Under New Jersey law, a result of 14.9 ppb requires no mandatory action. Yet at that concentration, a child drinking two cups of water per day from that fixture is consuming roughly 3.5 micrograms of lead daily — a dose that, accumulated over months and years, causes measurable neurological harm. NJ Clean Stream advocates for mandatory notification for any result above 5 ppb and mandatory remediation above 1 ppb.

What the report should contain

A complete, compliant school lead testing report should include: a unique identifier for every outlet tested; the date and time of sample collection; the laboratory method and detection limit (which should be 1 ppb or lower); a comparison to the action level for every result; and post-remediation confirmatory testing results for any outlet that previously exceeded the action level.

If your district’s report is missing any of these elements, ask for complete documentation. If the detection limit is reported as 5 ppb or 10 ppb, the test cannot detect low-level contamination that may still harm children.

The difference between good and bad remediation

Outlet-level replacement: necessary but often insufficient

The most common remediation response is replacing the fixture at the outlet that tested high — installing a new fountain head, a new faucet, or a new drinking fountain. New fixtures contribute minimal lead to the water. But if the supply line feeding that fixture still contains lead solder joints, or if the building’s service line is made of lead, the new fixture will simply deliver water that has already picked up lead on its way to the tap. Initial post-remediation testing may look favorable because the worst lead source has been removed — but levels may creep back up as remaining lead sources continue their work.

Flushing protocols: a management tool, not a fix

Many districts respond to lead findings by implementing a flushing protocol — running water at each outlet for 30–60 seconds before the building opens each morning. Flushing reduces first-draw lead levels by displacing the stagnant, lead-laden water. It is a legitimate short-term exposure reduction measure — but it is not remediation. It does not remove lead from the plumbing. It requires consistent implementation every morning, including after every weekend and school break. If flushing is skipped — and it will sometimes be skipped — children are exposed to the full first-draw concentration. A school that has been “flushing as remediation” for years without addressing underlying plumbing is managing a known lead risk with no endpoint.

Point-of-use filtration: effective when properly maintained

Installing certified point-of-use filters — certified to NSF/ANSI Standard 53 for lead reduction — can reduce lead by 99 percent or more. The critical caveat is maintenance. Filters have a rated capacity beyond which they no longer effectively remove lead. In a high-use school setting, filters may reach their rated capacity in weeks or months. A filter that has exceeded its rated capacity may actually concentrate lead in the water passing through it. Effective filtration requires documented maintenance schedules and regular cartridge replacement.

Plumbing replacement: the real solution

The only permanent solution is replacing the lead-containing materials — service lines, supply pipes, solder joints, and fixtures — with modern, compliant materials. This is expensive and disruptive. It requires planning and construction time. But it is the only approach that eliminates rather than manages the exposure. Full plumbing replacement should be the long-term goal of every school district’s lead remediation plan, prioritized by risk — starting with buildings that show the most widespread exceedances and the oldest infrastructure.

What different result patterns tell you

Isolated high result at a single outlet is most likely a fixture-level problem. Replacing that fixture is likely effective, though sequential sampling should confirm the supply line is clean.

Multiple elevated results in the same area suggests a shared plumbing problem — a lead-soldered branch pipe or shared supply line serving that zone. Fixture replacement alone will not solve this.

Elevated results building-wide with no clear pattern suggests either a building-wide plumbing issue or a water chemistry problem accelerating leaching throughout the system. This is the most serious pattern and requires the most comprehensive response.

Results elevated in a previous cycle but now non-detect may reflect successful remediation — or changed sampling conditions, pre-flushing, or other factors that reduced results without addressing the lead source. Confirm that remediation work was documented.

Blood lead testing: the other piece of the picture

Water testing tells you what’s in the water. It doesn’t tell you what’s in your child’s blood. If your child attends a school with documented elevated lead results — particularly if results were elevated before being identified and remediated — tell your pediatrician. The CDC recommends blood lead testing for children who may have been exposed. A blood lead level above the CDC reference value of 3.5 micrograms per deciliter warrants follow-up.