The Lisbon Water Department serves the community of Lisbon, Androscoggin County, ME, supplying groundwater to around 6,643 people through 2,657 connections. Government records from the EPA show a health-based violation on file for the system, alongside detailed sampling data including the lead 90th percentile measure taken at plumbing outlets. This page explains what the publicly available figures mean for your household’s safe drinking water after your existing equipment has failed.
What a Certified Laboratory Test Reports and How to Read It
Certified laboratory tests for water quality constituents such as lead report concentration as milligrams per liter (mg/L) or parts per million. For instance, the Lisbon Water Department’s recent sampling shows a lead 90th percentile concentration of 0.0016 mg/L measured in 2025. This value is derived from testing water at customer taps across the system, reflecting plumbing influences rather than only source water quality.
Understanding this reading requires recognizing that it reflects the upper boundary of lead found in 90% of sampled locations. A certified lab report includes this percentile data to help water systems and residents assess potential plumbing-related risks.
How Seasonal or Multi-Year Variation Shows in the Record
Water quality data for the Lisbon system includes samples taken over multiple years, indicating how concentrations can vary seasonally or annually. The lead measure cited, dated December 31, 2025, represents one point in time within a broader sampling program. Other constituents and measures reported by the system may vary as source water conditions and treatment processes change over time.
Understanding these temporal variations is important because water chemistry can fluctuate with weather patterns, water usage, and maintenance activities, affecting measured values in any given year.
What the Measured Range Means Against Federal Standards, and What It Does Not Mean
The EPA sets action levels and health-based standards for contaminants such as lead in drinking water. The 90th percentile measure reported for the Lisbon Water Department is a plumbing distribution figure, not a direct source water reading. It informs compliance monitoring but does not alone indicate unsafe water at any particular household.
It is also important to note that a detection or measured concentration below an action level is not a violation nor a guarantee of safety or unsafe water; rather, it is one data point within a spectrum of regulatory and treatment considerations.
A Worked Example: Reading the Record's Median and Range as a Homeowner Would
A homeowner looking at the Lisbon Water Department data sees that the lead 90th percentile is 0.0016 mg/L based on sampling from their community system. This value means that 90% of the sampled household tap water had lead concentrations at or below this number, as of the latest test.
However, this does not specify the lead level in any particular home, including yours, especially if plumbing conditions differ. To know your home's water composition precisely, testing your tap water with a certified laboratory is the only way.
What 'Detected', 'Median' and 'Range' Mean in the Sampling Record on This Page
In EPA water system records, 'detected' means a constituent was measurable by the testing equipment but does not imply a violation or unhealthy level. 'Median' refers to the middle value in a series of measurements, providing a typical concentration. 'Range' represents the spread from the lowest to the highest concentration found during sampling, capturing variability.
For the Lisbon Water Department, these terms apply to data points such as the lead 90th percentile and other treatment process indicators logged in their EPA records.
Understanding these terms helps you interpret what the public water system data indicates—and what it does not—about your water quality.
In conclusion, the publicly available data for the Lisbon Water Department gives a useful overview of local water quality but does not reveal the exact state of your household’s water, especially after equipment issues. Testing your tap water with a certified lab is essential for precise knowledge. Equipment such as the Pentair Safe Drinking Water Filter, which ships ready to configure, can be a direct-purchase option to address concerns about water quality at the point of use, providing an additional safeguard for drinking water safety in your home.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2025-12-31. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA SDWIS record for LISBON WATER DEPARTMENT (ME0090870), groundwater supply, serving 6643 people: 1 health-based violations of 12 total; lead 90th percentile 0.0016 mg/L
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