Johnston, SC Water Safety: 99/100 (2026)
1 ZIP code · 4 water systems · Updated 2026-06-03
Across Johnston, EPA monitoring data shows low violation rates and healthy safety margins — a pattern that places the city well above SC's average for drinking water compliance across recent reporting cycles.
How Johnston Compares
Data: EPA SDWIS Last verified: 2026-06-03
Key Facts for Johnston Residents
- Average lead level: 0.0005 mg/L.
- Homes built before 1986: 64% — older plumbing may contain lead solder.
- CDC health risk index: 14.82 — above typical levels.
Johnston's Water Providers
Johnston, SC is covered by 3 major water utilities out of 4 federally tracked systems, each managing its own pipes, treatment processes, and EPA filings. What a household gets from the tap depends on which provider's system serves that address.
Overview
We track water quality and home safety data for 1 ZIP code in Johnston, South Carolina (population ~5,375), covering 4 community water systems serving approximately 37,173 people region-wide.
No EPA violations recorded across any ZIP codes in Johnston — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Johnston: A (99/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
Johnston water systems draw from: Groundwater.
Lead & Copper
- Average lead level (90th percentile): 0.0005 mg/L (EPA action level: 0.015 mg/L)
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 3 (Low Risk)
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 29832 | A | Edgefield Company W&sa (1920001) | 29,200 |
All ZIP Codes in Johnston
- 29832 [A]
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
Johnston Community Health Snapshot
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
Johnston Infrastructure Age
With 64% of homes built before 1986, lead solder in plumbing is a potential concern. The EPA banned lead solder in 1986, but many older homes retain original plumbing.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
When more than half a city's housing predates the 1986 federal ban on lead solder, plumbing-era lead risk becomes a citywide concern rather than an exception. Johnston's median build year of 1975 places it squarely in that category.
Over half of homes in Johnston were built before 1986, when lead solder was banned. Older plumbing may leach lead into drinking water, especially with corrosive water chemistry.
Source: U.S. Census Bureau ACS B25034.
Johnston: Lead Risk & Vulnerable Populations
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
Even where utility-side monitoring meets Lead and Copper Rule requirements, the 64% pre-rule share in Johnston keeps interior-plumbing variation as a household-level question that aggregate data cannot resolve.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Deep Dive Reports
Detailed analysis for Johnston, SC