Service Line Material Minimum Verification Requirements

Michigan.gov/EGLE 800-662-9278 Rev. 2/2024

SERVICE LINE MATERIAL VERIFICATION

Minimum Requirements

A reliable inventory of potable water service line materials is important for service line replacement

planning, effective asset management, and notification of citizens served by lead service lines.

Reliability and completeness of service line records can vary both across and within water supplies;

therefore, it is important that supplies take steps to verify service line materials and records. Water

supplies are not expected to physically verify every service line, but rather a statistically sound

subset. To effectively evaluate the accuracy of service line records and/or predict service line

materials, a representative, uniformly random number of service lines must be physically verified.

Information gathered through random material verification processes provides:

• A verified estimate of the proportion of each service line material and material configuration

across the distribution system, providing a sound basis for planning service line replacement

and notification efforts.

• A basis for evaluating the reliability of existing service line material records and identifying

areas where additional physical verification or information may be needed. For water

supplies with high confidence in existing records, this may serve to demonstrate that

records are, in fact, reliable.

• A baseline data set for predicting materials at other locations (in combination with other

information).

This random material verification process does NOT provide:

• The service line material configuration of every building served; or

• The extent to which specific areas of the distribution system may differ from the system-wide

average occurrence rate of each service line material.

Verification Exceptions:

• A water supply may avoid the material verification process if all potable water service lines

within the water supply meet the strict definition of “known” described below.

• Water supplies may exclude from this verification service lines four inches or more in

diameter. Guidance for addressing these service lines as part of the Complete Distribution

System Materials Inventory (CDSMI) will be provided separately.

Timing of Verification:

It is recommended that water supplies conduct this verification early enough in the CDSMI process

to allow sufficient time for additional work, as needed, before the CDSMI is due to the Michigan

Department of Environment, Great Lakes, and Energy (EGLE) by October 16, 2024. Consider

completing this verification by the end of 2022, thereby allowing an additional two years to

undertake any additional activities that may be necessary to complete the inventory.

MINIMUM SERVICE LINE MATERIAL VERIFICATION REQUIREMENTS

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Random Material Verification Process

To evaluate the accuracy of potable water service line records and/or predict service line materials,

a statistically sound, uniformly random number of service lines should be physically verified. Some

supplies have already conducted recent physical verifications and/or have controls in place that

dictate service line materials, resulting in a very high level of confidence in the materials of some

service lines. In recognition of this, the following protocol requires random verification of only those

service lines of “unknown” material.

For the purpose of this verification, a conservative approach is used to determine when a service

line’s material can be characterized as “known” and be excluded from the verification process.

To be considered “known,” and therefore excluded from the pool of sites from which a random

sample will be drawn, a service line must meet criteria 1 or 2 below:

1. The service line was recently

physically verified and all of the following apply:

• ALL points, as defined in Step 5 below, were recently physically verified;

• The physical verification was well documented as to the material at each point; AND

• The water supply has not observed deviations from these records during operations and

maintenance.

2. Ordinances or controls were in place and all of the following apply:

• Ordinances

or other controls

were in place at the time the service line was installed

specifying materials used in service line construction AND

• The water supply has not observed deviations from these ordinance(s) or control(s) during

operations and maintenance.

“Recently” in this context is water supply-specific. Supplies must define recent to include a time after which its

records have been demonstrated to be reliable. No records prior to 1989 may be considered recent for the

purpose of this portion of the verification process. The use of lead service lines was officially prohibited in

Michigan in 1988; therefore, the health risk due to unreliable records is higher before this date. This does not

mean service line records prior to 1989 have no value. They may have great value in finalizing a system’s CDSMI,

but they cannot be used to exclude a location from the pool of sites from which random sites are selected for this

verification.

An ordinance is defined as: A law, statute, or regulation enacted by a municipal corporation. An ordinance is

a law passed by a municipal government. A municipality, such as a city, town, village, or borough, is a political

subdivision of a state within which a municipal corporation has been established to provide local government to

a population in a defined area.

A control, for the purposes of this guidance, is defined as: A general set of approved specifications or binding

construction documentation that explicitly demonstrates that there were controls in place dictating the material

usage in all public and private portions of a service line. Any controls must first have been explicitly adopted by the

water system or directly defined for each blueprint used in construction.

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Any service line that does not meet one of the two criteria above is considered “unknown” for

the purpose of this verification process and should be included in the list of locations from which

a set of sites will be uniformly randomly selected for verification.

NOTES:

• Service lines four inches or more in diameter may be excluded from the verification process.

• This definition of “known” and the three- or four-point verification process described in the

following Step 5 are specific to this baseline verification process and may not apply to

other aspects of the CDSMI. Further guidance on completing the rest of the CDSMI will be

provided at a later date.

Material Verification Process Steps

Step 1: Identify all potable water service lines of “unknown” material.

Identify all potable water service lines of “unknown” material (i.e., those not meeting the criteria of

“known” provided above). Determine the total number of these “unknown” service lines. Service

lines four or more inches in diameter may be excluded from this verification process.

Note: For the purpose of this verification process, assumed service line materials cannot be used to

classify a service line as “known.”

Step 2: Identify how many service lines should be physically verified.

• Water supplies with fewer than 1,500 “unknown” service lines must physically verify at least

20 percent of the total number of “unknown” lines.

• Water supplies with 1,500 or more “unknown” service lines must physically verify enough

lines to reach a 95 percent confidence level. See Appendix A to determine the number of

service lines requiring verification.

Step 3: Randomly select service lines for physical verification.

From the list of “unknown” service lines identified in Step 1, randomly select enough service lines

to at least meet the number requiring physical verification as determined in Step 2. Selection must

be uniformly random and not selected based on any specific criteria which can introduce bias. In

other words, each “unknown” service line must have an equal chance of being chosen for

verification. See Appendix B for an easy way to generate a uniformly random set of locations for

verification.

Note: It may be tempting to introduce a “logic” to the site selection process, such as selecting

within periods of construction or targeting portions of town. However, doing so can unintentionally

bias the data set so use a truly random selection method such as the one described in Appendix B.

MINIMUM SERVICE LINE MATERIAL VERIFICATION REQUIREMENTS

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Step 4: Create a tool for tracking records and materials during verification.

Create a spreadsheet (or other tracking mechanism) containing the randomly selected locations

identified in Step 3. Include columns or fields for tracking both existing records and results of the

physical verification. In this step, enter currently available information about service line materials

based on pre-verification records. See Appendix C for an example spreadsheet.

Step 5: Conduct three- or four- point physical verification.

Three or four points of physical verification are required for each service line. Physical verification

methods may include potholing (by a variety of methods including hydro-vac, air-knifing, hand

digging, etc.), trenching, televising, and in-home inspections. Always record the actual material

observed for each point described below, even if the material was as expected. Do not use “non-

lead” to describe the material.

Each service line requiring verification must have the following three or four points physically

verified (numeric bullets refer to the numbered location in the illustration above):

1. Interior portion of the service line up to the first shutoff valve or 18 inches inside the building,

whichever is shorter.

2. Curb stop to building, a minimum of 18 inches from the curb stop.

3. Main to curb stop, a minimum of 18 inches from the curb stop.

4. Lead connector (gooseneck/pigtail), if present. In this context, a gooseneck or pigtail is a

short section of material, typically not exceeding two feet, which can be bent and used for

connection between a rigid fitting (corporation stop) and the service line piping.

MINIMUM SERVICE LINE MATERIAL VERIFICATION REQUIREMENTS

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If a lead connector is present, a water supply must EITHER:

• Conduct a physical verification.

• Have a control that was in place demonstrating they were never used, OR

• Assume locations with galvanized service lines between the main and curb stop contain

(or previously contained) a lead connector. If a water supply makes this assumption, they

may skip physical verification of the gooseneck material.

Note: Unless assuming the current or previous presence of a lead gooseneck, most water

supplies with galvanized service lines between the main and curb stop must physically verify

the connector material.

Step 6: Record results of physical verification in the spreadsheet created in Step 4.

In the spreadsheet or tracking tool created in Step 4, enter the service line material observed at

each point of the service line during the physical verification conducted in Step 5. Always record the

actual material observed, such as lead, copper, plastic, galvanized steel, or other. Do not use “non-

lead.”

Step 7: Evaluate results of physical verification.

This representative, uniformly random sample of service line materials should be, with a high

probability, representative of service line materials from the portion(s) of the system from which the

random set was selected. You can use this information to assess the reliability of your existing

records and make sound assessments/decisions as you complete a system-wide inventory.

Assess Reliability of Existing Records:

Compare the historical records of your randomly selected sites with the new physically verified

materials for those sites to evaluate the reliability of your water supply’s historical records. For

example, what percent of the time did the physical verification match the historical records? If

historical records are found to be unreliable, additional physical verification may be necessary.

Predict Service Line Materials at Other Locations:

The results of this verification, in combination with other available information, can be used to

predict service line materials at other sites. Water supplies may need assistance with this

process. Additional information will be provided in a separate guidance document.

Retain Verification Records

Create, compile, and retain documentation of your verification efforts. You may be asked by EGLE

to produce or submit these records.

MINIMUM SERVICE LINE MATERIAL VERIFICATION REQUIREMENTS

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Beyond This Verification

This is not the end of the CDSMI process. As noted in Step 7, additional verification may be

necessary if records are found to be unreliable, additional work may be needed to build-out the

inventory, notifications to residents may be necessary, reporting to EGLE will be required, etc.

Additional guidance on these steps will be provided later.

Lead Service Line Notification Reminder:

Written notification must be provided to the owner and occupant(s) of any building with a service

line known, or assumed, to contain lead in any portion.

This guidance was created in collaboration with the University of Michigan and with consideration of the

ASDWA/BlueConduit white paper “Principles of Data Science for Lead Service Line Inventories and

Replacement Programs (www.asdwa.org/2020/09/25/asdwa-blueconduit-release-white-paper-on-lsl-data-

methods.)

EGLE does not discriminate on the basis of race, sex, religion, age, national origin, color, marital status,

disability, political beliefs, height, weight, genetic information, or sexual orientation in the administration of

any of its programs or activitie

s, and prohibits intimidation and retaliation, as required by applicable laws

and regulations.

To request this material in an alternate format, contact EGLE-Accessibility@Michigan.gov or 800-662-9278.

MINIMUM SERVICE LINE MATERIAL VERIFICATION REQUIREMENTS

A - 1

Appendix A:

Minimum Number of Service Lines Requiring Physical Verification

Number of “Unknown”

Service Lines*

Number to Physically

Verify

Fewer than 1,500 20% of “unknown” lines

1,500

306

1,600

310

1,700

314

1,800

317

1,900

320

2,000

322

2,200

327

2,400

331

2,600

335

2,800

338

3,000

341

3,500

346

4,000

351

4,500

354

5,000

357

6,000

361

7,000

364

8,000

367

9,000

368

10,000

370

15,000

375

20,000

377

30,000

379

40,000

381

60,000

382

90,000

383

225,000 or more

384

* For the purposes of this verification process, this represents the number

of service lines that do

NOT meet the criteria for “known” service lines

described at the beginning of this document. If the number of

“unknowns” falls between two values on the chart, either interpolate or

round up to the higher number.

MINIMUM SERVICE LINE MATERIAL VERIFICATION REQUIREMENTS

A - 1

Appendix B:

Generating a Uniformly Random Set of Services Lines for Verification

A spreadsheet (such as Microsoft Excel or Google Sheets) can be used to generate a uniformly

random set of “unknown” locations for verification using the following steps:

1. In the first column of a spreadsheet, list every unique service location of “unknown”

material. They can be listed by address, service line ID, or other identification method.

2. In the second column, generate uniformly random numbers, so that each service line is

associated with a randomly generated number, using the following steps:

a. Enter the following formula in the second column: =RAND( )

b. Put the ‘=RAND( )’ formula next to each location.

c. This generates a number between 0 and 1 for each location.

d. Then select the column with the random values and use the spreadsheet’s “Copy”

feature.

e. Then use the “Paste Special” option to “Paste Values Only” in the same column that

you have already selected. This will ensure your random numbers remain static.

f. Then use the “Sort” feature to list the randomly generated numbers from lowest to

highest. If the “Sort Warning” appears, select “Expand the selection,” then “Sort.”

3. Select only the top N homes, where N is the number requiring verification. For example, if

you need to verify 20 locations, select the first 20 locations on the list. These are the 20

uniformly random locations requiring verification.

Here is a short online tutorial for generating random samples in Microsoft Excel. The same formulas

and method work for Google Sheets.

MINIMUM SERVICE LINE MATERIAL VERIFICATION REQUIREMENTS

C - 2

Appendix C:

Example Field Verification Tracking Spreadsheet

Service Line ID &

Location

Service Line Material

Based on HISTORICAL RECORDS

Service Line Material

Based on FIELD VERIFICATION

Parcel ID/

Service

Line ID

Address

Connector

(gooseneck)

Historical

Record

Main-to-

Curbstop

Historical

Record

Curbstop-

to-Home

Interior

(18” or 1

shutoff)

Date of

Historical

Record

Type of

Record

Year

Built

Connector

(gooseneck)

Verified

Material

Main-to-

Curbstop

Verified

Material

Curbstop-

to-Home

Interior

(18” or 1

shutoff)

Date

Verified

Method

1234567

23 Main St

Copper

Unknown

1958

Copper

1/2/2020

Hydrovac

1234567

60 1st Ave

Copper

Unknown

12/1/1956

Note

1951

Copper

12/6/2019

Hydrovac

1234567

12 Michigan

Unknown

Copper

1927

Lead

Galvanize

Lead

6/20/2020

Excavation

1234567

34 2nd Ave

Lead

Galvanize

Copper

11/22/202

Hydrovac

1234567

941 W Main

Copper

3/15/1986

Permit

1954

Copper

11/13/201

Hydrovac

1234567

24 North St

Lead

Galvanize

Copper

1935

Lead

Galvanize

Lead

10/25/202

Excavation

1234568

26 Grand

Unknown

Copper

Unknown

6/15/1929

Note

1926

Copper

Lead

Copper

11/28/201

Excavation

1234568

13 24th St

Lead

Galvanize

Copper

Unknown

1/11/1952

Note

1871

Lead

Galvanize

Galvanized

5/25/2020

Hydrovac

NOTE: This table is only an example. Water supplies must document the location, existing records (if available), and findings of the physical

verification. Water supplies should consider adding any additional columns that will capture data useful to the verification process or

completion of the CDSMI.

MINIMUM SERVICE LINE MATERIAL VERIFICATION REQUIREMENTS