Lead service line identification and replacement field guide for plumbers

The lead service line, and where the public side ends and yours begins

A lead service line, or LSL, is the buried pipe that carries water from the public main in the street into a building, when that pipe happens to be made of lead. On properties built or plumbed before the mid-1980s, that buried run is often the single largest source of lead in the drinking water, because the water sits against bare lead and picks it up on the way to the tap. Newer homes generally do not have one. The age of the property is the first clue, not the last.

The service line has two halves, and they have two owners. The public side runs from the tap at the main to a point near the property line, commonly the curb stop, and the water utility usually owns it. The private side runs from there into the building, and the property owner usually owns it. Where exactly the line of responsibility falls varies by utility, so confirm it before anyone digs. The water service guide on this site covers the tap, corporation stop, curb stop, and meter in detail, and that geography is the same one a lead replacement works inside.

Lead can be on either half, or both. A house can have a lead public side and a copper private side, or the reverse, or lead end to end. That split is the whole reason full replacement matters, and it is the first thing the field work has to establish: what is each half made of, and who is responsible for it.

Why lead in drinking water is the part you do not get wrong

Lead is a neurotoxin, and the public-health position is that there is no safe level of it in drinking water. The harm falls hardest on infants and young children, where even low exposure is linked to lost IQ, attention and behavior problems, and developmental delay, and on pregnant women, because lead crosses to the fetus. Adults are not spared, with cardiovascular and kidney effects on the list. This is not a taste or odor complaint. It is a permanent injury that does not announce itself, because lead in water has no color, smell, or taste.

Flint is the reason most people outside the trade know the term at all. When the water source changed and corrosion control was not maintained, the protective scale inside the lead lines broke down and lead flooded into homes. The lesson the industry took from it is the one that drives the current rules: a lead line is a hazard you manage every day with chemistry, and the only permanent fix is to take the lead out.

That is what the EPA rules now require utilities to do, on a clock. Treat the lead as the controlling fact of the whole job. Everything else, the method, the schedule, the material, serves the goal of getting lead away from the water people drink.

Where the lead actually comes from

The lead service line is the biggest source by far when one is present, because it puts the most lead surface in contact with the most water for the longest time. But it is not the only source, and replacing the line without dealing with the others leaves lead in the system.

Lead solder is the second one. Copper pipe joined before the 1986 federal ban on lead solder was commonly sweated with 50/50 lead solder, so a pre-1986 copper system can leach lead at every joint even though the pipe itself is fine. Brass is the third. Older brass valves, fittings, and faucets contained meaningful lead until the lead-content limits tightened, and water sitting in a brass body overnight can pull lead from it. The fourth is galvanized pipe that used to sit downstream of lead, which gets its own section below, because the rule treats it as lead for replacement purposes.

The practical point for identification is that a clean copper service line does not prove the water is lead-free. Check the line, then check the joints, the fixtures, and any galvanized that was ever fed by lead. The water test is how you find out whether the other sources are contributing once the line is settled.

How do you identify a lead service line?

You identify a lead service line with two cheap tools: a key or a flat-head screwdriver to scratch the pipe, and a magnet. Find the service line where it enters the building, usually at the basement or crawlspace wall ahead of the meter or main shutoff, and scratch the bare metal in a spot you can see clearly. The color the scratch reveals, plus whether a magnet sticks, tells you the material.

Lead is soft, so the key bites into it easily, and the fresh scratch turns a bright shiny silver. A magnet will not stick to it. That combination, soft, scratches to shiny silver, non-magnetic, is lead. Copper scratches to the color of a new penny, a coppery brown, and a magnet does not stick. Galvanized steel is hard, so it resists the scratch, stays a dull gray, and a magnet sticks firmly to it. Plastic is obvious by feel and color and is neither. The magnet is what separates lead from galvanized, because both can read silver-gray at a glance and the magnet ends the argument: it grabs galvanized and ignores lead.

Lead pipe also tends to be a dull gray with a slightly swollen, wiped look at joints, often joined with a bulb-shaped lead-wiped fitting rather than threads. Scratch in a clean spot, not on corrosion or paint, and scratch both the public-side entry and any visible private-side run, because the two halves can be different metals.

The full set of identification methods

The scratch and magnet test at the entry point is the fastest and most reliable field check, but it only sees the pipe you can reach. A complete identification uses several methods together, because the buried run between the main and the building is the part you cannot scratch.

Start with the records and the age of the property. Utility tap cards, plumbing permits, and the construction date narrow the odds fast: a property plumbed before the mid-1980s is a candidate, one built well after is usually not. Then do the visual scratch and magnet test at the building entry, and where possible at the curb stop, to capture both halves. A first-draw water test tells you whether lead is reaching the tap, though a clean test does not prove the line is lead-free, because corrosion control may be holding the lead back for now.

When the visible ends disagree or the buried material is still unknown, the line gets exposed. Potholing, digging a small inspection hole at the curb stop or near the building, lets a crew scratch the buried pipe directly. A camera can sometimes be run, and some utilities use less invasive checks, but a physical look at the metal is the standard that settles an unknown. Until both halves are confirmed, the inventory records it as unknown, which under the current rules is handled as if it could be lead.

What is the EPA Lead and Copper Rule?

The Lead and Copper Rule is the federal drinking-water regulation governing lead in public water systems. The original rule dates to 1991. It was updated by the Lead and Copper Rule Revisions (LCRR) and then by the Lead and Copper Rule Improvements (LCRI), finalized in 2024, which together push utilities toward finding and removing lead service lines rather than just managing them chemically.

Two duties drive the field work. First, every community water system had to build an inventory of its service lines, classifying each as lead, galvanized requiring replacement, non-lead, or unknown, with that effort tied to deadlines the EPA set for an initial inventory and a later baseline. Second, systems must replace their lead and galvanized-requiring-replacement lines, with the LCRI setting a target of full replacement over roughly a 10-year period and requiring a publicly available replacement plan. The rule also addresses the lead action level and the monitoring that triggers wider action.

The exact deadlines, the action level, and the replacement pace have specific dates and figures in the rule, and they have been subject to phase-in and to legal and administrative review. Do not quote a date or a number from memory on a job. Confirm the current LCRI requirements, your state's adopted version, and your utility's replacement plan, because the rule sets the floor and the state and utility fill in the schedule that actually applies to a given address.

What is the difference between full and partial lead line replacement?

A full replacement removes the lead on both halves of the service line, the public side and the private side, so no lead pipe is left between the main and the building. A partial replacement removes only one half, typically the utility's public side, and leaves the owner's private-side lead in the ground. Full is the goal. Partial is the trap.

The reason is counterintuitive and worth stating plainly: a partial replacement can make the lead worse, at least for a while. Cutting into and disturbing an old lead line breaks up the protective mineral scale that has built up inside it over decades, and joining new pipe to old lead can set up a galvanic couple that accelerates corrosion at the junction. Studies after partial replacements have measured lead at the tap spiking above the action level and staying high for weeks to months, in some cases the better part of a year, before the scale re-forms. So a household can end up with more lead right after a partial job than before it.

This is why the current rules and most utility programs press for full replacement and discourage partials. If circumstances force a partial, the aftercare is not optional: aggressive flushing, an NSF/ANSI 53 filter certified for lead, and a plan to remove the remaining lead. Telling a homeowner a partial replacement made their water safer is, in the period right after the work, often the opposite of true.

Open-cut and trenchless replacement methods

Once the decision is made to pull the lead, there are two broad ways to get the new pipe in: dig the whole line out, or pull or burst new pipe through the old path. The right one depends on the soil, the obstacles, the surface above, and what the utility allows.

Open-cut is the conventional method: trench the full length of the service, lift out the old lead, lay the new pipe, and backfill. It gives a clear view of the line, makes connections straightforward, and is often simplest on short runs or where the path is already torn up. The cost is the surface: a trench across a yard, a driveway, or a sidewalk has to be restored, and that restoration is frequently the most expensive part of the job.

Trenchless methods avoid most of the open trench by working from small pits at each end. Pipe bursting pulls a bursting head through the old line, fracturing it outward while drawing the new pipe in behind. Directional drilling bores a new path and pulls the new pipe through it. Pulling new pipe through, or in some cases lining, are variations on the same idea. Trenchless saves the yard and the driveway and usually shortens the job, but it needs working pits, suitable soil, and a path clear of other utilities, so it is not always the option even when it is the one the homeowner wants.

What the new pipe is made of

The replacement line is not lead, and not galvanized. The common choices are copper, usually a heavier wall type for direct burial, or plastic, either high-density polyethylene or cross-linked polyethylene. Whatever goes in has to be approved for potable water and for the burial conditions, and that approval is where the standards live.

Copper for an underground service is typically a thicker-wall type than interior tube, commonly Type K, because it has to survive soil and pressure for decades. It is rigid, proven, and easy for inspectors to accept. The plastic options trade some of that for flexibility and the ability to pull through a trenchless bore. High-density polyethylene (HDPE) comes in long coils, fuses into a continuous joint-free run, and pulls well in pipe bursting. PEX is used for water service in some jurisdictions and not others.

The non-negotiable is certification. Any pipe and fitting in contact with drinking water should be certified to NSF/ANSI 61 for material safety, and the low-lead content requirements apply to the wetted brass and bronze fittings as well. Material choice is also partly the utility's call, because they will own and maintain the public side, so confirm the approved materials list before ordering. The wrong but cheaper pipe is a re-pull, not a savings.

Coordinating the utility and the owner for a full pull

Because the line has two owners, a full replacement usually takes two parties acting together, and the coordination is where these jobs succeed or stall. The utility handles the public side from the main to the property line. The owner, through a plumber, handles the private side from there into the building. A full replacement happens when both sides come out at once.

The worst outcome is two partial jobs separated by months. The utility replaces its half on its schedule, the owner has not arranged the private side, and the result is a partial replacement with all the lead-spiking problems described above, plus a second mobilization later to finish. Many utility programs now schedule the two halves together precisely to avoid this, and some fund or perform the private side to make it happen. Find out which model your utility uses before you quote the owner's portion.

On the plumber's side, the job is to be ready when the utility is: private-side line located, material approved, permit pulled, building shutoff and re-connection planned, and the homeowner briefed on the flushing and filtering they will need to do after. Showing up to replace a private side while the public side is still lead is doing a partial replacement, whatever the paperwork calls it.

Flushing and aftercare once the line is replaced

Replacing the pipe disturbs decades of scale, so the work is not done when the new line holds pressure. The line and the building plumbing have to be flushed hard to clear loosened lead-bearing particles, or the household drinks the debris the job kicked loose. Skip the flush and you can hand back water worse than what you found.

Flush thoroughly at high flow after the replacement. Utility guidance on duration varies, with recommendations commonly running from about 15 minutes up to an hour of full-flow flushing, so follow the specific instruction from the water system. Run the cold taps, starting at the lowest fixture, with aerators removed, because the screens catch the very particles you are trying to expel. Then clean or replace the aerators, since they trap sediment that keeps shedding lead afterward.

Aftercare does not end at the flush. Advise the household to keep using an NSF/ANSI 53 lead-certified filter for a period after the work and to keep flushing the tap before drinking until lead levels settle, because particulate lead can keep appearing for weeks as the new scale forms. The water treatment guide on this site covers filter selection and point-of-use options in more depth. The replacement removed the source. The flush and filter handle the mess it made on the way out.

Is it safe to drink water from a lead service line?

Treat water from a known lead service line as not safe to drink unprotected, especially for infants, young children, and pregnant women, until the line is replaced. Because there is no safe level of lead and you cannot see, smell, or taste it, the conservative position is the only defensible one while lead pipe is still in the ground.

Until replacement, three interim measures reduce exposure, and they stack. Use a filter certified to NSF/ANSI 53 for lead, on a pitcher or at the tap, for any water used for drinking, cooking, or mixing infant formula, and replace the cartridge on schedule, because a spent filter stops working. Use only cold water for drinking and cooking, since hot water dissolves more lead, and never make formula or fill a kettle from the hot tap. And flush the tap before drawing water that will be consumed, running it until it turns cold, to clear water that sat against the lead overnight.

These steps lower the dose. They do not make a lead line safe, and they depend on someone doing them correctly every time, which is exactly why they are a stopgap and not a substitute. The water treatment guide covers filter ratings and selection. The permanent answer is removing the lead, and the interim measures only buy time until that happens.

Corrosion control buys time, it does not cure

Utilities reduce lead leaching system-wide with corrosion control, most commonly by dosing orthophosphate, which builds a protective mineral coating on the inside of lead pipe so less lead dissolves into the water. It is real, it works, and Flint is what happens when it is neglected or disrupted by a source change.

But corrosion control is a chemical lid on the problem, not a fix. The lead is still there, the coating is fragile, and anything that disturbs the pipe, water-chemistry shifts, pressure events, or the physical disturbance of construction, can release a slug of lead. Partial replacements are a textbook disruption of exactly this protective scale.

For the field, the takeaway is twofold. Do not let a utility's good corrosion control program become an argument for leaving lead in the ground, because the program manages risk rather than removing it. And understand why aggressive flushing matters so much right after any work: you have just disturbed the scale that corrosion control spent years building, and the water needs to carry the loosened material out before anyone drinks it.

The lead water test and what it tells you

A lead water test measures the lead concentration at the tap, and the sampling method matters as much as the lab result. A first-draw sample, collected after water has sat in the plumbing for several hours, captures the water that was in longest contact with any lead and shows the worst case for that period. A flushed sample shows what the line delivers when water is moving. Both tell you different things, so follow the exact protocol the test kit or utility specifies.

Read the result against the EPA action level for lead, but read it carefully, because a single low reading does not clear the property. Lead release is intermittent: it depends on standing time, temperature, water chemistry, and whether a particle happened to break loose during that draw. A clean test on a known lead line means the corrosion control is working that day, not that the lead is gone.

The action level itself is a number set in the rule, and the LCRI changed the framework around it, so confirm the current value and what triggers action with your state program and utility rather than quoting a figure from memory. The test is a useful input to the inventory and to the homeowner's decisions. It is not a substitute for identifying and removing the lead.

Galvanized pipe downstream of lead has to go too

Galvanized steel pipe is not lead, but galvanized pipe that was ever installed downstream of a lead service line is treated as if it were, and for good reason. The zinc coating and the rough steel surface absorb lead from the water passing through them over years, and they keep releasing that stored lead long after the lead pipe upstream is gone. The rules call this galvanized requiring replacement, sometimes shortened to GRR, and it is a large category in the national inventory.

The trap is fixing only the obvious lead and leaving the galvanized. A crew replaces a lead service line, the homeowner believes the lead problem is solved, and the galvanized interior or service pipe that spent decades downstream of that lead keeps dosing the water. The lead reading can stay high and nobody understands why, because the visible lead is gone.

When you identify galvanized in a building, the controlling question is its history: was it ever fed by a lead service line or lead pipe? If it was, or if you cannot rule it out, plan to replace it along with the lead. Confirm how your state and utility classify and require GRR replacement, because the definitions and obligations sit in the rule and its state adoption.

Cost and the funding that may cover it

Lead service line replacement is not cheap, and the surface restoration on an open-cut job is often the line item that surprises people. The good news for owners is that they frequently do not pay the full sticker price, because there is significant public money flowing into this work.

Federal infrastructure funding has put billions toward lead service line replacement, much of it routed through state programs and the Drinking Water State Revolving Fund, and many utilities run programs that replace the private side at reduced cost or no cost to the owner as part of a coordinated full replacement. Grants, low-interest loans, and utility cost-share arrangements all exist, and they vary widely by location and change as funding cycles turn.

For a plumber quoting an owner, the practical move is to check the utility's program before pricing the private side as if the owner pays for everything. An owner who is told the job costs thousands out of pocket, when their utility would have covered it in a coordinated replacement, may delay and leave the lead in the ground. Confirm what is available locally and time the private-side work to the utility's program.

Older facilities and large buildings

Most of the attention goes to houses, but older commercial buildings, schools, multifamily properties, and aging facilities of all kinds, including the older buildings that get repurposed into data centers and light industry, can carry the same lead service lines and the same pre-1986 lead solder and brass.

The wrinkle in a large or old facility is scale and complexity. The service may be larger, the interior piping is more extensive, and there can be lead solder and galvanized scattered through a system that was added onto over decades. Identification follows the same scratch-and-magnet logic, but it takes more points of inspection, and the records are often incomplete. For potable-use buildings, schools and child-care facilities especially, sampling at fixtures matters because the problem can be the interior plumbing as much as the service line.

The principle does not change with the building type: find the lead wherever it is, replace the service line fully, deal with the solder and the galvanized-downstream-of-lead, and verify with sampling. Confirm any facility-specific monitoring obligations with the state program and the AHJ.

What to document and the inventory record

Identification only counts if it is written down in a form the utility's inventory and the next crew can use. For each service, record the material of both the public side and the private side, how you determined it, the location of the inspection, and the date, because an entry that just says lead with no basis cannot be defended or verified later. An unknown is a valid and important entry: it tells the utility this address still needs investigation.

Capture the identification method specifically, scratch and magnet at the entry, potholed at the curb, from utility tap records, or confirmed during replacement, so a reviewer knows how solid the call is. A material confirmed by exposing and scratching the buried pipe is stronger than one inferred from the building age. Tie the record to a photo where you can, and log it the same day, on the device, so it does not live on a scrap of paper in a truck. Capturing the material, the test, and a photo on a field tool like FieldOS keeps the inventory entry attached to the job it came from.

This record is also the homeowner's history and the utility's compliance evidence. Keep it precise.

Common mistakes

• Doing a partial replacement and leaving the other side's lead, which can spike lead at the tap for weeks to months.
• Not flushing thoroughly after the work, so loosened scale and particulate lead reach the tap.
• Sending the homeowner off without an interim NSF/ANSI 53 lead filter and flushing instructions.
• Misidentifying the material: calling galvanized lead, or lead galvanized, by skipping the magnet.
• Leaving galvanized pipe that was downstream of lead, which keeps releasing absorbed lead after the line is gone.
• Trusting a single clean water test as proof the line is lead-free when corrosion control is masking it.
• No inventory record, or an entry with no basis, so the classification cannot be verified later.
• Quoting the owner the full private-side cost without checking the utility's funded replacement program.

Field checklist

Standards and references

The federal framework is the EPA Lead and Copper Rule, as revised by the Lead and Copper Rule Revisions (LCRR) and the Lead and Copper Rule Improvements (LCRI). Those rules set the service-line inventory duty, the replacement requirement and its roughly 10-year target, the lead action level, and the monitoring that triggers wider action. The dates, the action-level figure, and the replacement pace are specific and have been subject to phase-in and review, so verify the current LCRI text, your state's adopted version, and your utility's replacement plan rather than relying on a remembered number.

AWWA standards and manuals govern the service-line work itself, the materials, the tapping, and good practice for replacement, and they sit alongside the utility's own specifications and approved materials list. For materials in contact with drinking water, NSF/ANSI 61 covers material safety and the low-lead content requirements for wetted brass and bronze. For the interim and aftercare filters the household relies on, NSF/ANSI 53 is the certification for lead reduction, covering both soluble and particulate lead, though performance depends on using and changing the filter correctly.

The plumbing code, the IPC or UPC as adopted, governs the private-side line inside the property, and the water utility governs the public side and the tap. As with the water service work, the state program, the utility, and the AHJ control the specifics. Cite the rule and the standard that actually controls the point, and confirm the deadlines, the action level, and the local requirements against the current sources before you put them on a job.

Units, terms, and abbreviations

Lead-in-water work uses a handful of terms and abbreviations that show up across the rule, the utility paperwork, and the lab report, and they are easy to mix up.

Lead concentration at the tap is reported in micrograms per liter, written as ug/L and equal to parts per billion (ppb). The service line is the LSL; galvanized requiring replacement is GRR. The rule names are LCR, LCRR, and LCRI. NSF/ANSI 61 is the pipe and fitting safety standard; NSF/ANSI 53 is the lead-reduction filter standard. First draw means the sample taken after water has sat in the plumbing; corrosion control is the treatment, often orthophosphate, that limits leaching.

LSL

Lead service line, the buried pipe from the main to the building when it is made of lead

GRR

Galvanized requiring replacement, galvanized pipe downstream of lead that absorbed and re-releases lead

LCR / LCRR / LCRI

EPA Lead and Copper Rule, its Revisions, and its Improvements; the federal rules for lead in drinking water

ug/L (ppb)

Micrograms per liter, equal to parts per billion, the unit for lead concentration at the tap

NSF/ANSI 61

Certification for the safety of materials in contact with drinking water, including low-lead fittings

NSF/ANSI 53

Certification for point-of-use filters that reduce lead, both soluble and particulate

First draw

A sample taken after water has sat in the plumbing for hours, showing worst-case lead contact

Corrosion control

Utility treatment, often orthophosphate, that coats lead pipe to limit how much lead dissolves

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