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Preliminary distribution system materials inventories

Preliminary distribution system materials inventories

Michigan’s drinking water regulations require public water supplies to maintain an inventory of service line materials in their distribution systems. By January 1, 2020, public water supplies were required to submit a Preliminary Distribution System Materials Inventory (PDSMI) to the Michigan Department of Environment, Great Lakes, and Energy (EGLE). The primary focus of the PDSMI was for water supplies to review their existing records and report what is known and unknown regarding service line materials. This provides important information for planning service line material verification and replacement efforts. On this page are service line material estimates provided by water supplies in their PDSMI.

Service line materials categories

Water supplies were required to summarize potable water service connections by broad material categories as follows:

4% known Lead, 1% Known Galvanized Previously Connected to Lead (GPCL), 7% Unknown - likely lead, 11% Unknown- no information, 24% Unknown, likely not lead; 53% - No Lead or GPCL

dark blue square icon (4%; 103,891) Known lead: Any portion of the service line contains lead.

orange square (1%; 28,884) Known galvanized previously connected to lead (GPCL): A galvanized service line that was previously connected to lead.

gray square (7%; 176,110) Unknown - likely contains lead: While not known for certain, service lines the water supply believes are likely to contain lead.

yellow square (11%; 293,630) Unknown – material(s) unknown: Service line materials are fully unknown. Supply has no information regarding the likelihood of lead being present in the service line.

blue square (24%; 640,717) Unknown - likely does not contain lead: While not known for certain, service lines the water supply believes are not likely to contain lead.

green square (53%; 1,414,445) Contains neither lead nor GPCL: Service lines that are known to contain no lead in any portion. These typically include copper, plastic, cast iron, or galvanized that was NEVER connected to lead.

Download the estimates

Note the following data limitations:

  • The numbers provide are estimates. These estimates are based on information available to the supply at the time of PDSMI submittal. Supplies are expected to improve knowledge of distribution system materials and submit a final inventory by October 16, 2024.
  • The numbers provided are a snapshot in time. The numbers are based on water supply information at the time of PDSMI submittal. Supplies may have updated information or replaced service lines since submitting the information below.
  • The numbers provided are subject to change. Clarifications or revisions may be requested of water supplies which could result in changes to the data below. Some water supplies may also submit updated information as it becomes available.
  • The numbers provided represent the most recent information submitted. While water supplies were required to report by January 1, 2020, some supplies have submitted updated PDSMI data since their original submission. The Month/Year Submitted column indicates when the information was received.