Lead service lines in the Chelmsford area: the 2026 inventory

What the inventory shows as of September 2026

Headline finding: All 31 Massachusetts towns in the service area have their community systems on file with MassDEP, and no system shows a lead result above the 15 ppb action level in either the state view or its 2025 report. Among 2025 90th-percentile results we could verify, Reading reads highest at 8.39 ppb, followed by Bedford at 3.7, North Chelmsford at 3.6, Sudbury at 3.5 and Westford at 2.9, while Andover, Lawrence, Lowell and Littleton reported zero or non-detect. Two towns break the pattern structurally: Carlisle has no community water system at all, and Stow runs on small condo and school systems rather than one town-wide supplier.

Do not read the state lead flag as zero lead: The statewide view carries a has-lead flag that reads zero or NO for every system here, yet Andover reported removing 206 lead service lines from 2022 through 2025, Lawrence reports up to 57 possible lead lines and 345 of unknown material, Reading lists verified lead services under its replacement program, and Stoneham removed 15 in 2024. The flag is a summary field, not a count, so this article reports known lead lines only from supplier documents. Where suppliers describe their own inventories, the pattern is lead mostly gone and unknown-material lines as the open question: Bedford inspected 129 unknown lines in 2025 and found no lead, and Woburn found no lead lines but a few galvanized ones.

Chelmsford in detail: Three separate districts serve Chelmsford, which is why the answer depends on your street: Chelmsford Water District with 8,382 services, North Chelmsford with 2,929 and East Chelmsford with 685. All three filed inventories with no action-level exceedance, with 2025 90th-percentile results of 2.4 ppb for Chelmsford Water District and 3.6 ppb for North Chelmsford. That three-district split also shapes PFAS answers across town, covered in our PFAS guide.

How to use your row: Find your town, confirm the system name against your water bill, read the lead figures as system-wide background rather than a tap reading, and check the replacement section below before assuming anything about your own service line. A clean system row does not clear any individual house, since customer-owned portions vary pipe by pipe. Houses built before 1986 deserve a direct check with the supplier regardless of the town row.

How to read each column

System and services: The system name and service-connection count identify which supplier the row describes, so compare against your bill before drawing conclusions. Multi-system towns list each community supplier with its own figures, while condos, schools and workplaces on separate small systems appear only in the statewide file rather than this table. Private-well streets sit outside every inventory by definition.

State view lead result: This column is the lead result MassDEP lists for each system in its inventory data view, converted from milligrams per liter to parts per billion. It is not always the latest round: Stoneham shows 8.7 in the state view but reported 1.44 for 2025, and Littleton shows 1.1 against a 2025 non-detect. Where the view lists zero, the table says not listed, because a blank result and a true non-detect look the same in that field.

2025 report 90th percentile and notes: The next column is the 90th-percentile lead result from the supplier 2025 water quality report where we could read it, meaning nine of ten sampled homes were at or below that level. The notes column records known lead lines, removals and inventory progress stated by the supplier itself. A dash means we could not verify a 2025 figure in September 2026, not that the supplier has none.

The 31-town table

Reading guide: Rows cover community water systems by town from the statewide inventory view pulled September 2026, with 2025 supplier report figures and notes added where verified. Lead figures are in ppb. Every row is at or below the 15 ppb action level in both sources; full methodology follows the table.

Standout rows: Reading pairs the highest verified 2025 result at 8.39 ppb with an active, mapped replacement program. Andover shows why the state view can mislead: it lists 13.8 ppb, yet Andover reported a 2025 90th percentile of zero after removing 206 lead lines from 2022 through 2025. Lawrence is the town with the most lead lines still possibly in the ground, up to 57 plus 345 unknown. Stoneham and Bedford show what finished inventory work looks like, with Stoneham reporting no lead services left and Bedford clearing 129 unknowns without finding lead. Carlisle and Stow carry structural notes instead of system rows.

Methodology: where every number comes from

Dataset and pull: Every row starts from the statewide service line inventory data view published through the Massachusetts inventory hub, pulled September 2026. System names, service counts and the lead result field come verbatim from that view, with lead converted from mg/L to ppb and zeros shown as not listed. The 2025 90th-percentile figures and lead-line notes come from supplier reports read directly: MWRA 2026 community reports for Bedford, Burlington, Lexington, Reading, Stoneham, Wilmington and Woburn, 2025 reports for Chelmsford Water District, North Chelmsford, Billerica, Tewksbury, Westford, Pepperell, Concord, Littleton, Sudbury, Andover, North Reading, North Andover, Lawrence, Lincoln, Maynard, Lowell and Methuen. No figure comes from our own jobs.

Classifications used: Inventories classify each service line as lead, galvanized requiring replacement, non-lead, or lead status unknown, and systems had to file initial inventories by October 16, 2024 with consumer notices for lead, galvanized, or unknown lines. The federal rule finalized October 2024 requires identification and replacement of lead pipes within ten years. The state has-lead flag is left out of the table on purpose, since it reads zero even for systems whose own reports describe known lead lines.

Coverage limits: Nashua and Hudson fall under New Hampshire rather than Massachusetts programs, so they sit outside this table and its inventories; the federal rule still applies and their annual water quality reports hold the local numbers. Carlisle and Stow rows carry structural notes because no single community system serves those towns. Small non-community systems such as schools appear in the statewide file but outside this community-system table.

What the findings mean for your home

Unknown lines matter most: Systems across the state still carry unknown-material lines awaiting verification through records review, field inspection, and the newer in-pipe testing methods. A notice classifying your line as unknown triggers annual letters until the material is proven or replaced, so responding to verification requests shortens the cycle. Contact your supplier directly to check your address rather than inferring from the town row.

Pre-1986 homes first: Federal and state guidance both flag homes built before 1986 for possible lead service lines depending on local ordinances and eras, regardless of how clean the town row reads. The Plumbing Age Index shows which towns hold the deepest pre-1940 and mid-century stock, and those same towns deserve the earliest address-level checks. Flushing taps after long stagnation and using certified filters remain sensible interim steps where lead is possible.

Replacement posture varies: Reading runs a mapped replacement program with an online inventory for every property, Stoneham removed its 15 known lead services in 2024, Andover removed 206 from 2022 through 2025 under a consent order, Lawrence replaced 5 more in 2025, and Bedford spent 2025 inspecting unknown lines and found none were lead. Most towns replace system-owned portions while owners handle customer-owned halves, detailed in the next section. Ask your supplier which posture your town holds before budgeting anything.

Who pays for lead service line replacement in Massachusetts

Ownership decides: Cost follows ownership entirely, and ownership varies by town and system rather than by any statewide flat rule. Where the line splits at the curb stop, the system pays its half and the homeowner typically pays the customer-owned half. Where the town owns the whole line, replacement is the system responsibility, and where owners hold the full line to the meter, the full replacement generally falls on the homeowner.

Programs change the math: Some systems offer free or discounted replacement programs, outside funding, or coordinated scheduling that lowers the real outlay well below full price. Homeowner insurance sometimes contributes where policies include service-line coverage. Because programs open and close by budget year, the current answer always comes from a direct ask rather than from any guide, including this one.

No-compulsion rule: Massachusetts drinking water rules do not force homeowners to replace their own lead lines, though the state strongly encourages it and systems must keep sending annual notices while lead or unknown lines remain. Coordinating with the supplier before self-funded work matters, since joint scheduling often cuts both sides costs. Keep every notice, test result, and program letter with the home records.

When should you call about lead or old supply lines

Call signals: Call about supply-line help when a notice names your line as lead, galvanized, or unknown, when first-draw water discolors, when pressure fades house-wide on old piping, or when a remodel opens walls over suspect supply runs. Homes with repeated pinholes pair naturally with repipe planning rather than single-spot repairs. Testing through the supplier or a certified lab settles material questions that age alone cannot.

What to say on the call: Call (978) 592-1168 with your town, supplier name, notice wording, home build era, and any test results ready. Describe discoloration timing, pressure behavior, and which fixtures show it first. That account lets the visit sequence testing, mapping, and renewal options correctly across Chelmsford, Andover, and Reading. Ask how openings, restoration, and pressure proof will be handled before any wall is cut.

Records that help most: Keep inventory notices, test sheets, program letters, and the leak log in one folder with your town row printed on top. Homes that bring all four get faster diagnoses and narrower proposals. Update the folder yearly and after every plumbing visit, since replacement programs and sampling rounds move on annual cycles.