Total Trihalomethanes (TTHM)
Unresolved Total Trihalomethanes Rule violation cited in 2020 (total trihalomethanes (tthm)).
PWSID SC4650042 · GroundwaterPrivate
52 people served. No health-based SDWIS violations recorded in the past 5 years. 8 remain unresolved. Last cited 6 years ago.
Unresolved Total Trihalomethanes Rule violation cited in 2020 (total trihalomethanes (tthm)).
Unresolved Total Trihalomethanes Rule violation cited in 2020 (total trihalomethanes (tthm)).
Unresolved Total Trihalomethanes Rule violation cited in 2020 (total trihalomethanes (tthm)).
Unresolved Total Trihalomethanes Rule violation cited in 2020 (total trihalomethanes (tthm)).
Health-based violations exceed an MCL or treatment-technique standard. Monitoring violations are reporting failures with no measured exceedance — they tell you the system isn't fully transparent, not that the water is unsafe today.
Failure to monitor as scheduled
Failure to monitor as scheduled; returned to compliance
Failure to monitor as scheduled
Failure to monitor as scheduled
Failure to monitor as scheduled
Failure to monitor as scheduled
Failure to monitor as scheduled; returned to compliance
Failure to monitor as scheduled
Failure to monitor as scheduled
Failure to monitor as scheduled
Columbia, South Carolina (Census place; block-group disparity scores aggregated by centroid containment): a service population of 136,754. Local disparity score for pm2.5 (fine particulate) sits below the reference (70). Why we surface this →
Low-income
People of color
Under age 5
Over age 64
| Indicator | Disparity score | Reading |
|---|---|---|
| PM2.5 (fine particulate) | 70 | below the reference |
| Ozone | 28 | well below the reference |
| Nitrogen dioxide (NO₂) | 97 | near the reference |
| Diesel particulate | 111 | moderately above the reference |
| Toxic releases (RSEI) | 127 | moderately above the reference |
| Traffic proximity | 110 | near the reference |
| Lead-paint risk (pre-1960 housing) | 85 | below the reference |
| Superfund site proximity | 61 | below the reference |
| RMP-facility proximity | 133 | moderately above the reference |
| Hazardous-waste site proximity | 82 | below the reference |
| Underground storage tanks | 132 | moderately above the reference |
| NPDES wastewater proximity | 121 | moderately above the reference |
| Drinking-water non-compliance | 5 | well below the reference |
Source: Census ACS 2018-2022 (5-year) + USEPA-clone EJ blockgroup stats (raw indicators + EJ disparity mirror).
Source. EPA Safe Drinking Water Information System · retrieved 2026-05-07. Reporting period 2020-01-01 → 2026-05-07.
What this is not. SDWIS records compliance against federal MCLs — not a direct readout of tap-water concentrations. Active health-based violations are not the same as a current crisis; we link to the EPA record so you can verify return-to-compliance status before forming a conclusion.