Lead in drinking water almost never comes from the source. It comes from the plumbing between the main and the tap: a lead service line, lead solder on copper joints, or brass fittings. That single fact governs how testing works, because the contact time between water and metal is what determines the reading, and a sample drawn carelessly can miss a real problem entirely.
Why the first draw sample is the important one
Lead dissolves into water that has been standing in contact with pipes and fittings. Water that has just run through the system at speed has had little contact time and will usually show little. A first draw sample, taken from a tap that has not been used for several hours, captures the water that has been sitting in the plumbing and is what people actually drink first thing in the morning. Follow the laboratory's stagnation instructions exactly: draw the sample cold, without running the tap first, and without removing or cleaning the aerator beforehand unless told to.
Sequential sampling locates where the lead is
One bottle tells you whether there is a problem. Several bottles drawn in sequence tell you where it is. Filling a series of containers one after another traces the water back through the plumbing: the first represents the tap and its fittings, later ones represent the internal pipework, and later still the service line to the street. That matters because the fix differs completely. A brass fitting is replaced in an afternoon; a lead service line is a shared job with the utility and a much larger undertaking, often with a partial replacement question attached.
Use a certified laboratory, not a strip
Lead is measured at very low concentrations and no consumer test strip resolves it meaningfully. Send the sample to a laboratory accredited for drinking water analysis, which will supply the correct bottles, the preservation requirements and the holding time. Before sampling, read your utility's annual report: the EPA notes that every community water system publishes a Consumer Confidence Report and maintains a finder for them. Utilities also often hold records of which service lines are lead, and many run free or subsidised testing programs worth asking about first.
What to do while you wait, and afterwards
Until you have a result, use cold water for drinking and cooking, since hot water dissolves lead more readily, and run a tap that has stood overnight before drinking from it. If the result shows lead, a filter certified for lead reduction at the point of use is the immediate step, and it must be certified for lead specifically rather than a general taste filter. Replacing the source of the lead is the durable answer. Our water testing guide covers choosing a laboratory and drawing samples for other contaminants at the same time.
Questions people ask about how to test water for lead
Should I run the tap before taking a lead sample?
No, not for a first draw sample. The point is to capture water that has been standing in contact with the plumbing, which is what a household drinks first thing.
Can a test strip detect lead?
Not usefully. Lead matters at concentrations far below what consumer strips resolve, so a certified laboratory analysis is the only meaningful test.
Does boiling water remove lead?
No. Boiling evaporates water and leaves the lead behind, so it slightly concentrates it. Use a filter certified for lead reduction instead.
Where does lead in tap water come from?
From the plumbing rather than the source: lead service lines, lead solder on older copper joints, and brass fixtures and fittings that contain lead.