What 'Detected', 'Median', and 'Range' Mean in Somerville’s Water Sampling Record
The Somerville Water Department’s public system record reports measured constituents in their supplied water but does not describe any one home’s water quality. A detection means an instrument found the constituent but is not a statement of safety or violation. Median values represent the middle result of a set of samples, while range shows minimum to maximum values recorded over time. These figures summarize the system’s distribution water data, which reflect water after it leaves the treatment plant and passes through public pipes, not private plumbing.
How Seasonal or Multi-Year Variation Appears in Somerville’s Water Quality Data
Somerville’s system reports include data points collected over multiple years, with the latest lead measurement from 2025. This timeline helps track trends or fluctuations possibly caused by source water changes or treatment adjustments. Seasonal variation might affect some parameters, but the system’s consistent sampling and reporting provide a stable snapshot of water quality conditions over time for planning treatment approaches.
A Worked Example: Reading Median and Range as a Somerville Homeowner
Consider the lead measurement at the 90th percentile, 0.00392 mg/L, reported in 2025. This value relates to plumbing materials in the public distribution system, not raw source water. The 90th percentile means 90% of sampled homes had levels at or below this. Understanding such percentiles helps homeowners realize their tap water can vary locally, so direct testing of their own water remains important before deciding on treatment.
What to Record Before Seeking Treatment Guidance
- Obtain your own water test results, focusing on contaminants of concern for your household.
- Note any noticeable tastes, stains, or other water quality issues experienced at fixtures.
- Gather information on your daily water use to match treatment capacity needs.
- Check local utility reports for updates on water quality and any health-based findings.
What Somerville’s Measured Ranges Indicate Compared to Federal Standards—and What They Do Not
The Somerville Water Department’s public record includes seven health-based violations out of eight total events reported, highlighting that certain water quality issues have been identified over time at the system level. However, these system-wide findings do not predict individual household water quality. Some reported measures, such as lead levels or other constituents, fall below health risk thresholds or are aesthetic benchmarks affecting taste or plumbing but do not constitute safety violations. Only a household-specific water test can establish actual conditions and treatment needs.
Summary of Somerville System Scope and Data Source
The Somerville Water Department serves over 81,000 residents through nearly 15,000 connections with surface water as a source. Their public system record provides water quality data representative of the community supply but not of any individual household. For more detailed information, consult the EPA’s public water system data directly at the provided government source.
For households evaluating treatment approaches, the C-Series Whole-Home + Drinking Combo System ships ready to configure and offers a documented capacity of 32,000 grains, making it a comprehensive option to address varied water quality concerns detected in the region’s public system record.
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 SOMERVILLE WATER DEPT. (MWRA) (MA3274000), surface water supply, serving 81045 people: 7 health-based violations of 8 total; lead 90th percentile 0.00392 mg/L