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Howard County D.p.w. Distribution

Columbia, MD · serves 286,158 · Purchased surface waterMD0130002
All clear
All monitored contaminants within federal limits. Last updated from the most recent CCR and EPA monitoring data available.
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Measured in your 2025 water report
From your utility's Consumer Confidence Report · 3 contaminants tested
Above limit
Approaching limit
Within limits
HAA5▸
28.1 µg/L · Dec 2025
MCLlegally enforceable
Sample history
Range: 4.6 to 31.6 µg/L across 31 samples (Mar to Dec 2025).
Compliance for HAA5 is calculated as a locational running annual average (LRAA), not single samples. This system's LRAA was 28.13 µg/L, within the 60 µg/L MCL.
What is it?
Another group of disinfection byproducts formed when chlorine reacts with natural organic matter. HAA5 measures the five most common species.
Why it matters
Long-term exposure above the MCL of 60 µg/L (0.060 mg/L) is associated with increased cancer risk. Like THMs, the MCL is based on a running annual average.
What to do
Activated carbon filters can reduce HAA5. If your system consistently approaches the limit, a reverse osmosis filter provides more complete removal.
TTHM▸
67.8 µg/L · Dec 2025
MCLlegally enforceable
Sample history
Range: 22.7 to 114.8 µg/L across 32 samples (Mar to Dec 2025).
Compliance for TTHM is calculated as a locational running annual average (LRAA), not single samples. This system's LRAA was 67.75 µg/L, within the 80 µg/L MCL.
What is it?
Formed when chlorine used to disinfect water reacts with natural organic matter. Includes chloroform, bromoform, and related compounds. The trade-off: disinfection prevents waterborne disease, but creates these byproducts.
Why it matters
Long-term exposure above the MCL of 80 µg/L (0.080 mg/L) is associated with increased cancer risk and possible reproductive effects. The MCL is based on a running annual average, not a single sample.
What to do
If your system is near or above the limit, an activated carbon filter (including pitcher filters like Brita) can reduce THMs. Running water for a minute before drinking also helps, as THMs are volatile and dissipate.
% of limit

CCR data in early access — values are extracted from utility PDFs and may contain errors. Verify with your utility's 2025 CCR report.

Source: HOWARD COUNTY D.P.W. DISTRIBUTION Consumer Confidence Report 2025 · Extracted by WaterScore
Measured data
Private Well Risk

Do you have or use a private well? Measured concentrations from nearby private wells sampled within 5 miles.

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1 site within 10 mi
Nearby Superfund Sites

1 EPA Superfund site within 10 miles. Proximity does not necessarily mean your water is affected.

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Surface water
Water Sources

Columbia draws from surface water — Cc-Md0300002-Tp99 and Cc-Md0150005-Tp02. Drought directly affects reservoir levels and river flow.

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Spatial context
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