Lead Service Line Inventories: Everything You Need to Know

Often, the EPA highlights a sobering statistic in its reports: there are an estimated 6 to 10 million lead service lines in the U.S. - a major public health crisis.

But why is this number “estimated”? And where are these lines exactly?

Anyone at a water system can answer this question: the data’s simply not there.

Most systems don’t have lead service line inventories. Many service lines have been in the ground for decades, and for the portion of the service line owned by the customer, systems understandably haven’t maintained records.

In other words, you’re not alone if you’re a water system and missing inventory data.

Enter: The Lead and Copper Rule Revisions (LCRR). Among the EPA’s changes to this law, water systems are now required to document the material of every service line in their territory.

Worried about compliance?

Before we explore how to maximize your resources - let’s start at the beginning: the inventory requirements.

Disclaimer: This blog post is not legal advice. The purpose of our series is to help unpack the Lead and Copper Rule but should not be relied on as legal counsel.

I. What’s Required In an LSL Inventory?

If you’re new to the Lead and Copper Rule Revisions, here’s a quick FAQ:

What’s the requirement?

Water systems must submit an inventory of every service line in their territory - including the material type for both the customer- and utility-owned portions of the line.

This inventory will be made available to the public and used as the basis for other initiatives, like Lead Service Line Replacement. Over time, systems will continue to refine the inventory by verifying information in the field and identifying the material of unknown lines.

EPA headquarters in Washington, D.C.

When is the LSL inventory due? Who does it apply to?

The initial inventory is due by October 16, 2024, and this requirement applies to all community water systems (CWSs) and non-transient, non-community water systems (NTNCWs) - regardless of size.

Do any water systems already have inventories?

Before the LCRR, some states had voluntary inventory surveys, and the original Lead and Copper Rule required rough material lists, but only a handful of states already require LSL inventories.

What’s next?

While the EPA plans on releasing Lead and Copper Rule Improvements (LCRI), they’ve made it clear the initial inventory requirements won’t be changed.

States are still working to implement the Lead and Copper Rule Revisions - and the EPA has yet to release guidance to states and water systems on the subject - but this doesn’t mean systems can’t get started documenting materials.

In fact, it’s critical this work begins early - as we’ll discuss later.

What goes into the inventory?

A water system must classify the customer- and utility-owned portions of the service line as…

  • Lead
  • Galvanized steel in need of replacement (if it was ever downstream of a lead line)
  • Non-lead (e.g., plastic or copper)
  • Lead status unknown

What’s a “Lead Service Line”?

This question isn’t as obvious as it may seem.

Take a closer look at the EPA’s definition in the LCRR:

Lead service line means a portion of pipe that is made of lead, which connects the water main to the building inlet. A lead service line may be owned by the water system, owned by the property owner, or both.

The private and public sides of a service line
Source: NPR

“For the purposes of this subpart, a galvanized service line is considered a lead service line if it ever was or is currently downstream of any lead service line or service line of unknown material.

“If the only lead piping serving the home is a lead gooseneck, pigtail, or connector, and it is not a galvanized service line that is considered a lead service line the service line is not a lead service line. For purposes of §141.86(a) only, a galvanized service line is not considered a lead service line.”

Here we see the basis for the EPA’s different LSL classifications - lead, galvanized in need of replacement, lead status unknown, etc. - but there’s one conspicuous exception: lead goosenecks, pigtails, or connectors.

A lead gooseneck laying on a table
Source: The City of Ann Arbor

We can add pipes with lead solder or alloy to that list as well, though not explicitly mentioned by the EPA.

Significantly, this means pipes that are made of lead or are joined with lead can be categorized as “non-lead” in the inventory.

Takeaway: it’s important to differentiate between what the EPA requires in the inventory with what water systems are wise to include.

A diagram of a service line, water main, and home
Source: LSLR Collaborative

With workers combing through records and unearthing pipes, now’s the time to document everything underground - including any material made of lead.

The more thorough and accurate the inventory, the easier it’ll be to comply with other parts of the LCRR and prepare for future water regulation.

Need a more detailed overview of the Lead and Copper Rule Revisions? Check out Unearth’s complete guide to the LCRR and take a deep dive in our side-by-side comparison of the LCR, LCRR, and LCRI.

II. What Should You Include In an LSL Inventory?

When building an inventory, the Association of State Drinking Water Administrators’ (ASDWA’s) guidance, symposium, and template are great places to start.

Make sure to check out the Lead Service Line Replacement (LSLR) Collaborative’s overview of LSL inventories as well.

Copper, lead, and steel service lines side-by-side
Source: Greater Cincinnati Water Works

To summarize their recommendations, you should document…

  • A location identifier and site ID
  • Both the utility-owned and customer-owned portions of the service line
  • The service line’s broad category - lead, non-lead, galvanized steel requiring replacement, and lead status unknown - along with more specific material information. (For instance, if the line’s “non-lead,” you should record whether it’s copper, a type of plastic, or some other material.)
  • Other materials that are lead (e.g., goosenecks, pigtails, connectors, solder, corporation stops, and alloy), copper (e.g., copper non-lead solder), of an unknown material, or relevant to lead exposure (e.g., brass and tube alloy).
  • The source of this information. (Tap cards? Customer survey? Field crew inspection? Statistical analysis?)
  • The inspection method. (Scratch test? Hydrovac?)
  • Any material records. (These are documented separately to compare against other data sources - so water systems can assess and substantiate the records’ reliability. More on that later.)
  • The date of service line installation
  • The tier criteria for the sampling plan
  • The type of building
  • The onsite water treatment in use
  • The site’s eligibility for LSLR funding 
  • The service line diameter and meter age
  • The building plumbing materials and their installation date

Of course, not all of this information is required for compliance with the Lead and Copper Rule Revisions. But other inventory lists in the past - like those in California or Illinois - highlight the importance of a comprehensive record.

In Illinois, for instance, nearly 370k of the 3.8 million service lines are copper with lead solder. If you identified these lines as “non-lead,” then you’d have no record of the lead solder. While this meets requirements, it misses critical information.

A copper service line with lead solder
Source: City of Southlake

By documenting lead solder, water systems can explain high lead levels in “non-lead” service lines and have the information they need in the future to truly get 100% of lead out of the ground.

Plus, investing resources in a robust inventory now not only helps with compliance in other parts of the rule but reduces the number of “lead status unknown” and “galvanized in need of replacement” lines - ultimately helping protect communities and cuts costs.

III. Why Creating an Accurate, Thorough Inventory is Critical

While the EPA allows for “lead status unknown” service lines in the initial inventory, it’s discouraged by other requirements in the rule.

The same goes for galvanized lines that must be categorized as “galvanized in need of replacement” simply because there’s not enough data to prove they were never downstream of a lead line.

Ultimately, water systems risk a complicated compliance process and unnecessary expenses in the future if they don’t get started early building an accurate, thorough inventory.

A pile of water pipes
Source: Pixabay / Public Domain

The cost of unknowns in the Lead and Copper Rule

Both “lead status unknown” and “galvanized in need of replacement” lines are included within a water systems’ tally of LSLs. This has serious repercussions since the inventory serves as the basis for the rest of the Lead and Copper Rule:

  1. With a high number of unknowns, water systems that surpass the “action” lead level will be required to replace a higher number of LSLs. This will lead to a significant number of required excavations - a major expense - as a water system continues to improve its inventory and search for actual lead service lines.
  1. When there’s little known about plumbing materials, it’ll be challenging for water systems to prove that their site sampling plan is representative of the community. This will further complicate compliance.
  1. As water systems reduce the number of unknowns, they’ll need to continually adjust other initiatives - including public education and lead sampling.
  1. If the tally of LSLs is inflated by unknowns, customers experience undue concern. This doesn’t reflect well on the water system.

In other words, there are implicit penalties in the EPA’s LCRR for systems that don’t have enough data on their service lines.

And if that wasn’t already incentive enough for a thorough inventory, states may also apply their own pressures. States may make it more difficult for water systems with patchwork inventories by requiring a certain level of evidence to qualify a service line as “non-lead.”

How do you prove a service line is non-lead?

At the moment, this is an open question.

Will every service line need to be excavated? Unlikely.

Will multiple sources of information be required for each service line? Possibly.

Will a water system need to substantiate its records with a representative dataset of inspections? Likely.

A field worker holding a lead service line
Source: Isaac Wasserman/Wisconsin Watch

The EPA will soon release guidance to states, and states will decide on their own criteria as they implement the LCRR, but water systems can be sure of one thing: they’ll need to defend the service line classifications in their inventory.

For this reason alone, water systems need to carefully document the methods, sources of information, and reasoning they use to create an inventory. The more thorough the record, the easier it will be to justify the inventory to state regulators.

To avoid future headaches, water systems need to take care in how they build an inventory from the very beginning.

IV. How Do You Build an LSL Inventory? 7 Steps

In the LCRR, the EPA instructs water systems to consult construction, plumbing, water system, and distribution system records while creating an inventory. Any other information sources must be approved by the state.

With that in mind, it’s important to keep an eye out for your state’s guidance on building inventories. But evolving state guidance shouldn’t keep you from collecting records, reaching out to customers, and getting inspection teams into the field.

As we argued above, evolving state guidance is simply another reason to carefully document all sources of information.

Let’s dive in.

Where should you start?

An American Water Works Association (AWWA) review article on inventory practices explains where to start as you begin documenting building materials.

A pile of lead service lines and goosenecks
Source: CMU Public Broadcasting

The AWWA researchers recommend the following progression:

  1. National & State Lead Bans
  1. Historical Records
  1. Visual Inspection
  1. Sequential Water Sampling
  1. Excavation

And there’s good reason to also pursue:

  1. Data Analytics 
  1. Emerging Technology

Let’s examine each of these in more detail.

1. National & State Lead Bans

In 1986, the Safe Drinking Water Act amendments prohibited lead pipe, solder, and flux within public water systems. Here, “lead-free” meant lead amounts couldn’t exceed 0.2% in solders and flux and 8% in pipe fittings.

The EPA's plaque on their headquarters building

Knowing this, water systems can use the construction date of buildings to identify non-lead service lines. Though some states may have prohibited lead earlier, states were required to implement the “lead-free” requirement by June 19, 1988.

Some water systems may choose to add two or three years to their state’s lead ban to be sure they don’t miss any LSLs installed by builders who had lead pipes still on hand and broke the law to empty their inventory.

It’s also important water systems are aware that new construction may have been hooked up to a lot’s existing service lines. Accordingly, you may need additional information from building permits, tax documents, and other construction records in cases where a lot’s service lines pre-exist the new construction.

Next, you can determine if local areas stopped using lead even earlier - drawing on records to identify exactly when and where lead was used throughout your territory.

Using property records and lead bans has the potential to confirm entire communities are lead-free and significantly narrow the scope of your project.

2. Historical Records

Even after ruling out large areas, however, you’ll still have many unknowns. This is where historical material records and legacy knowledge come in.

These include service line tie-cards, tap cards or tickets, building permits, plumbing codes and permits, distribution maps and drawings, inspection and maintenance records, meter installation records, plans for water main work, and permit files.

A water system tap card
Source: Harris Water Main & Sewer

Not every source will provide material type, but you can still pick up on other clues, like pipe size. Lead pipes were usually 1-inch or less in diameter.

Plus, legacy personnel can contribute their own experience, point you to the right records, and help assess the reliability of certain reports. Don’t hesitate to reach out to neighboring water systems as well - they may have insight into past practices.

Of course, these records may be unreliable or incomplete. This is especially true for private service lines that a water system didn’t document or manage in the past.

However, digitizing and centralizing all of this information will help identify which lines need to be inspected to verify the reliability of your data and fill in any gaps in your records.

3. Visual Inspection

It’s impossible to inspect the entirety of a service line without excavating it - but there are opportunities on the customer-side and during existing work to document parts of the line.


Customers, plumbers, community partners, or water system personnel can examine the portion of the service line that enters the home. There are simple tests anyone can perform with a magnet or coin to determine whether the pipe is copper, lead, or galvanized steel.

A scratch test of a lead service line
Source: City of Madison

NPR has an easy-to-use tool that walks people through this process, and many water systems have public-facing materials on their website or sent in the mail explaining how to perform these tests.

Check out these examples: DC Water, Green Bay, Madison, or Greater Cincinnati.

Customers can then send in a report or picture of their scratch test, and the water system can then follow-up to verify the report. And with people who are trained to perform these tests, no verification may be needed.

Existing Work

There are also opportunities for water systems to inspect the public side of the service line by ensuring clear communication between field teams and coordinating existing work.

For example, if there’s already a plan to perform work on a water main, it’s an excellent opportunity to document all service lines, goosenecks, pigtails, and connectors excavated in the project.

A water main replacement
Source: Watertown Public Works

In this, it’s valuable to equip these teams with a simple app or other intuitive data collection tool - so everyone can easily get involved in documenting materials.

4. Sequential Water Sampling

Water sampling is a less exact science and shouldn’t be relied on to categorize a service line as “lead” or “non-lead,” but it can provide an indication that a lead line may exist. This can highlight where a water system should prioritize its inspections.

A diagram of tap sampling in a home
Source: EPA

With tap water that’s sat stagnant for six hours, the first two liters have been sitting in the building plumbing while the following six liters are from the service line. Sampling these liters may show the presence of lead in the service line.

With effective CCT, however, the LSL may have a protective coating and return a negative lead result. For this reason, water sampling shouldn’t be used to assign “non-lead” status.

5. Excavation

Digging up the service line is a costly process - and certainly can’t be used for every unknown line you have in your inventory.

That said, you can’t see most of the service line unless you excavate it. This information is useful when leveraging data analytics, which we’ll discuss next.

There are two primary methods for excavating a service line:

1. Mechanical Excavation

In this method, you use a backhoe or other equipment to dig a hole in the ground. It’s pretty straightforward and reliably exposes the service line material. And because more earth is removed, more of the service line is revealed for inspection.

A mechanical excavation of a service line
Source: Bridge Michigan

But it’s also expensive and is a greater disturbance to the customer and traffic.

2. Vacuum Excavation

Vacuum excavation uses a hydro-vac truck to create a smaller hole. The truck breaks up the dirt with a stream of water while sucking up the earth with a powerful vacuum.

Though this is less invasive and expensive, the hydro-vac truck only exposes a small segment of the line, and you may not identify all of the lead in the ground.

A hydrovac truck performing a vacuum excavation
Source: Canessco Services Inc.

In the end, neither method is perfect.

As we noted earlier, water systems must leverage existing operations or construction work -  like a water main repair - to identify what they can. It’s critical there’s collaboration across an organization for this reason.

Also, water systems must accompany excavations with other sources of field information and leverage data analytics to resolve unknowns without digging up every pipe.

6. Data Analytics

The more information you have, the easier it will be to assess your data sources.

If excavations confirm utility records or institutional knowledge, for instance, then these reports can be trusted as more credible.

Machine learning can also help connect important dots. As you resolve more unknowns, you may learn that the location, age, or other detail of homes indicates a likelihood of lead. You can then be confident that an unknown service line with this data will probably be lead and need replacement. This information is vital in planning and getting the necessary funding.

Over time, this machine learning will become more and more accurate in its predictive analytics - cutting down on unnecessary excavations of non-lead lines.

In short, you’ll never have all the data that you want in your inventory - so it’s important to have the right tools to maximize the impact of this information.

7. Emerging Technology

There are some technologies that have potential to make inventorying easier.

A diagram of electrical resistance LSL identification
Source: The Water Research Foundation

For example, there are devices that use electrical resistance or acoustic waves sent through the pipe to identify its material. And some have even proposed using radar. But only time will tell whether these technologies can be proven in the field or shown to be cost-effective.

According to the Water Research Foundation, there’s “no silver bullet” to inventorying.

Ultimately, building an inventory is a significant challenge for water systems of any size.

Conclusion: 3 Keys to Maximizing Your Resources

From gathering and verifying data in the field to sharing information between various stakeholders, water systems face many hurdles in building an inventory.

With an immense undertaking ahead, it’s critical you maximize the resources you already have.

Get the lead out fast by empowering your teams with simple, digital tools and enlisting the support of your community.

1. Empower Teams with Mobile GIS

Everyone will need to pitch in to identify building materials.

Crews doing routine work - like a meter replacement or water main repair - will need an easy way to document any lead they find. Office employees may need to enter the field, and will require intuitive tools to capture information.

Plus, customer service and other departments across your organization will need visibility into the work in the field to ensure everyone is aligned.

In short, connection is key.

Here’s where mobile GIS comes in: simple map-based collaboration.

Picture a non-regular field worker walking up a driveway. In their pocket, a phone and app that connects them instantly to all of the records and activities attached to the building parcel beneath their feet. And simple forms to collect customer refusals, complete scratch tests, document lead pipes, and coordinate replacement.

Anyone within your organization can view progress in real-time, collaborate on a dynamic map of infrastructure and work, and communicate with ease.

If you have back-office GIS, you can bring all this field information into your GIS without providing direct access to your system of record.

With mobile GIS, you can rapidly onboard users, connect people to the information they need, and get everyone to work within your organization.

Now, let’s take this a step further.

2. Connect Your Community Digitally

Mobile GIS not only connects stakeholders within your organization but also people across your community. 

Imagine your community - local contractors, non-profit partners, regulators, citizens, and public officials - all connected digitally.

The same simple, digital forms that enable an office worker to easily document information in the field can be leveraged by a volunteer - a parishioner or university student - to ring a doorbell, speak with a customer, and do a scratch test by the meter.

And the same visibility into ongoing inspections and replacements that ensures alignment across your team can help you coordinate with public officials and share information with regulators.

The opportunities are endless, the technology is here, and the idea is simple: now is the time to document everything that’s underground and connect everyone you need to do just that.

3. Partner with Technology Companies

Here’s where technology companies like Unearth come in.

Tech companies have a responsibility to pitch in, understand your challenges, and provide you with the tools you need to keep our communities safe.

It’s not procurement - it’s a partnership.

With this in mind, Unearth’s leveraging a grant from the EPA to create easy-to-use tools to help water systems build LSL inventories and coordinate replacement.

If you’re a small water system, Unearth’s also launched a Small Community Program to get these tools into your hands for free - so you can get started on your work tomorrow.

Discover how Unearth’s Mobile GIS can connect your community.

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