What 'detected', 'median' and 'range' mean in the sampling record on this page
The term 'detected' in water sampling means instruments have measured the presence of a substance like lead, but it does not indicate a violation or unsafe condition. The 'median' is the midpoint concentration value in a set of data, giving an idea of typical levels. The 'range' covers the span from the lowest to the highest measured concentrations. For Warren County's public water system, the 90th percentile lead level recorded on June 30, 2026, was 0.0013 mg/L, a distribution measure that reflects lead presence in household plumbing rather than source water.
How public-system records differ from private-well testing in what they establish
Public system sampling data cover overall conditions affecting many connections and reflect the water quality as it is delivered through the distribution network. Private well testing, in contrast, reveals the specific quality of water from an individual source and can show variations caused by local geology or plumbing materials. To understand your home's lead levels, you will need to conduct a direct test of your tap water, as public system records cannot determine the condition of your household water.
How to compare this area's record with a neighbouring county's without overreading it
Comparisons between Warren County's lead level records and those of nearby counties should focus on general trends rather than exact values. Variations can arise from differences in water sources, treatment methods, and plumbing infrastructure. Because the 90th percentile lead measure reflects plumbing distribution, it cannot alone indicate the safety or quality of source water, nor confirm individual household conditions. Avoid assuming your water matches any specific sample in regional data.
How the constituent enters groundwater or the distribution system in this region
Lead in water primarily originates from corrosion of plumbing materials such as pipes, solder, and fixtures containing lead, rather than the groundwater source itself. In Warren County, groundwater is the source of supply, but lead detected in distribution network samples is typically from internal plumbing corrosion. Factors like water chemistry and pipe age influence how much lead dissolves into the water by the time it reaches your tap.
How sample depth, well depth or source type changes what a reader should expect
Sampling depth and well type affect what contaminants are detected. Groundwater wells in Warren County tap aquifers relatively deep underground, where naturally occurring elements vary less than in shallow sources. Lead is not usually present naturally in these aquifers but appears when it leaches from household plumbing. Therefore, local public water system lead levels primarily reflect distribution system conditions rather than source water quality.
Why aesthetic secondary standards differ from health-based limits, applied to this constituent
Lead has no EPA-established secondary standard for aesthetics because its concern is health-based. However, the public water system for Warren County reports no health-based violations related to lead. Exceeding thresholds for substances governing taste, staining, or corrosivity does not imply health risks but can affect water appearance and pipe longevity. Understanding this difference helps focus treatment on reducing health risks rather than cosmetic concerns.
Warren County’s public water system record applies to all 30,361 connections served by groundwater. For detailed data, visit the EPA’s Safe Drinking Water Information System at the government source link provided.
When existing household equipment struggles to manage lead, using a Fleck Lead in Water Filter, which ships ready to configure, is a documented method to reduce lead levels at the point of use. This system treats water to lower lead exposure where your current equipment’s capacity is limited.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2026-06-30. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA SDWIS record for WARREN COUNTY (OH8301512), groundwater supply, serving 81975 people: 0 health-based violations of 3 total; lead 90th percentile 0.0013 mg/L
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