How to Check Whether a Service Line Is Lead

Why this matters

A service line is the pipe that carries water from the utility's main in the street to the house. Millions of them in the US are still lead, mostly in houses built before about 1950 and some well after, because many places allowed lead service lines into the 1980s. A tech who can identify one in two minutes gives the household a fact the utility may not have, and a tech who does not know what it is can disturb it during an unrelated job and send lead particles to the kitchen tap that afternoon. This card is the field check any trade can do without becoming the plumber, and it stops where the plumber and the utility take over.

What the check can and cannot tell you

The scratch-and-magnet check identifies the material of the few inches of pipe you can see, usually between where the line comes through the foundation and the meter or main valve. It does not tell you what the line is under the yard, whether the utility's side of the line matches the house side, or whether the water is safe. Partial replacements are common: copper at the wall can be joined to lead ten feet out. Treat your result as one sample of one section, and say so in the record.

The steps

1. Look up the utility's inventory before you go in the basement. Under the 2021 federal Lead and Copper Rule Revisions, every community water system had to complete an initial service line inventory by October 16, 2024, classifying each line as lead, galvanized requiring replacement, non-lead, or lead status unknown, and make it publicly accessible, with systems serving more than 50,000 people required to post it online. The 2024 Lead and Copper Rule Improvements kept that inventory, require it to be updated, and set a replacement program, generally within ten years; parts of the 2024 rule came under EPA review in 2025, so re-check the current text before quoting a date to anyone. States run these programs and some add their own requirements on top. Why first: the record may already answer the question, and it tells you the utility's classification, which is the term the household will hear again. What breaks if skipped: you confirm copper at the wall while the inventory lists the address as lead on the utility side, and the household walks away believing they have no lead line.

2. Find where the line enters the house. Look on the street-facing side: a basement or crawlspace wall, a garage slab, a utility closet. Follow it to the meter or the main shutoff. In warm climates the meter is often in a box near the curb and the line rises out of the slab near a hose bib. Why: the exposed run between entry and the first valve or meter is the only part of the service line you can test without digging, and it is the part most likely to be original. What breaks if skipped: testing the interior distribution pipe and calling the service line by its result.

3. Read it before you touch it. Lead pipe is dull gray, looks thick for its size, bends in smooth curves rather than meeting fittings at angles, and is often joined at the wall or the valve with a bulbous, rounded wiped joint where molten solder was shaped by hand. Copper is brown, red or green with age and has soldered or compression fittings. Galvanized is gray and threaded. Plastic is plastic. Why: the visual read tells you where to test and flags the spots not to test. What breaks if skipped: scratching a weeping, bulged or visibly corroded section, which is the one place a light scratch can start a leak.

4. Do the magnet test. Hold a strong magnet, the kind on a pickup tool, against a clean spot. A magnet sticks firmly to galvanized steel. It does not stick to lead, copper or plastic. Why: it separates the two gray pipes, lead and galvanized, which is the identification people most often get wrong. What breaks if skipped: gray galvanized called lead, or gray lead called galvanized. Both matter: galvanized downstream of lead is its own classification.

5. Do the scratch test, gently. On a clean spot away from joints, draw the edge of a key or a coin across the pipe with light pressure, a mark a few millimeters long. Lead is soft: the scratch shows bright, shiny silver almost at once. Copper shows copper color. Galvanized resists and shows dull gray steel. Do not use a file, a knife or sandpaper, and do not dig; you want a surface mark, not a groove. Hazard at this step: the key now carries a trace of lead. Wipe it and your fingers with a damp disposable wipe, bag the wipe, and wash your hands before eating, drinking or smoking. The pipe surface itself is not an inhalation hazard from a scratch, which is one more reason the scratch stays light. What breaks if skipped: the identification rests on color, which oxidation makes unreliable.

6. Look at what the line connects to, without opening anything that is not yours. Note whether the house-side valve and meter connections are original or newer, whether the line changes material anywhere you can see, and the diameter. Do not open a utility meter box, pull a meter, or turn a curb stop; in most places those are the utility's equipment, and disturbing them is exactly what releases lead from a lead line. Why: a material change in view is direct evidence of a partial replacement. What breaks if skipped: a single-material verdict on a mixed line.

7. Record it so the utility can use it. Many utilities ask customers to submit photos to update their inventory. Give the household a record good enough for that:

SERVICE LINE CHECK                    (field record)
Address: ____________   Date: ______   Tech: ______
Utility inventory listing: lead / GRR / non-lead /
  status unknown / not found
Entry point: front basement wall, 22 in above floor
Visible length checked: 14 in, wall to main valve
Visual: dull gray, smooth curve, wiped joint at wall
Magnet: did not stick
Scratch: bright silver
Material change in view: copper after the meter
Reading: APPEARS TO BE LEAD (visible section only)
Photos: 3 (entry, scratch mark, meter connection)
Routed to: utility inventory + plumbing evaluation

Why: a record with the method and the visible length lets the utility and the plumber trust it, and the phrase "visible section only" keeps it honest. What breaks if skipped: a verbal "you have lead" that nobody can act on and nobody can check.

8. Route it, and tell the household what to do in the meantime. Route to the utility (inventory update and its replacement program) and to plumbing; see related: Lead Service Line Identification and Notification, the plumbing SOP. For the interim, repeat mainstream EPA and CDC guidance rather than inventing your own: use cold water for drinking, cooking and baby formula; a filter certified to NSF/ANSI Standard 53 for lead reduction is a recognized interim measure; and lab testing through the utility or a certified laboratory is how the water itself gets answered. Who owns which part of the line and who pays to replace it varies by city and state; this is not legal advice, and the household's question goes to the utility first. What breaks if skipped: a family that knows it has a lead line and has no idea what to do until the utility calls back.

Why disturbing the line releases lead

Over decades a lead service line builds a mineral scale on its inner wall, and that scale is much of what keeps lead out of the water. Cutting the line, wrenching a valve on it, digging beside it, vibration from equipment or a sudden pressure change can crack that scale loose and release lead particles, which is why short-term lead levels can rise after a partial replacement. The federal rule puts notice and flushing duties on the water system when its own work disturbs a lead line. When your crew is the one disturbing it, nobody will tell the household unless you do.

The shop's starting default when a job on a suspected lead line requires shutting the main or working near the entry: tell the household before, then after the water is back on, remove the aerators and run each cold tap at full flow for at least five minutes, starting at the lowest floor, and clean the aerators before refitting them. Follow the utility's published flushing instructions where it has them, which take precedence over this default.

Worked example: an irrigation tie-in in a 1925 house

An irrigation crew needs to tie a new backflow assembly into the copper supply in the basement of a 1925 house. The utility's online inventory lists the address as lead status unknown.

The tech finds the line entering the front wall 22 inches above the floor, with 14 inches of pipe visible before the main valve. It is dull gray, bends in a smooth curve, and meets the valve at a rounded wiped joint. The magnet does not stick. A light key scratch shows bright silver. After the meter, the pipe is copper. The record above is filled in exactly as shown, with three photos.

The tie-in itself is on copper downstream of the meter, so the irrigation work is not on lead. But the tie-in requires shutting the main valve, which sits directly on the lead line. The tech tells the homeowner before shutting it, closes the valve slowly rather than snapping it, makes the tie-in, opens the valve slowly, then runs the flush default: aerators off, each cold tap at full flow for five minutes, basement first. The backflow assembly is tested per its own requirements.

The job closes with the record sent to the household and the utility's inventory link, and a plumbing referral.

What would have changed the plan: if the main valve had been stiff or weeping at the stem, the crew would not have forced it. A valve that fails while turning on a lead line turns a tie-in into an emergency repair on a lead line, so the job pauses for the utility to isolate at the curb or for a plumber to replace the valve.

How to verify you did this right

• The record names the visible length and says "visible section only." A verdict on the whole line is a claim you cannot support.
• The magnet and scratch results are both recorded. Either alone is weaker; together they separate lead from galvanized and copper.
• No utility equipment was opened or turned.
• The household was told before and after any valve on the line moved, and the flush was done and noted.

References

• US EPA, Lead and Copper Rule Revisions (2021) and Lead and Copper Rule Improvements (2024), service line inventory requirements; check current status of the 2024 rule.
• EPA and CDC consumer guidance on lead in drinking water; NSF/ANSI Standard 53 (drinking water treatment units, health effects), as the certification EPA points consumers to for lead-reducing filters.
• See related: Lead Service Line Identification and Notification; Lead Service Line Replacement Standard (plumbing SOPs).
• See related: Galvanized Supply Pipe and What Its Age Means; Recognize, Record, Route: The Rule for Legacy Materials.