431,001 people (2024 Census estimate, +5.1% since 2020)
918 square miles of land · 469 people per square mile
“Highest” and “lowest” are just order, not grades: a high rank for poverty or hazard losses means more of it. Each figure's source is in its section below.
15 active community water systems list Charleston County in the area they serve, reporting 428,625 people served in all (a system that crosses county lines counts its whole population).
| CHARLESTON WATER SYSTEM (SC1010001) surface water · local government · SC1010001 | 278,771 served |
| MT PLEASANT WATERWORKS (SC1010002) buys surface water · local government · SC1010002 | 91,500 served |
| ST JOHN'S WATER (SC1020002) buys surface water · private · SC1020002 | 22,592 served |
| KIAWAH ISLAND UTILITY (SC1010008) buys surface water · local government · SC1010008 | 9,550 served |
| ISLE OF PALMS W/S COMM (SC1010004) buys surface water · local government · SC1010004 | 9,530 served |
| SEABROOK ISLAND TOWN OF (1010009) buys surface water · private · SC1010009 | 5,939 served |
| FOLLY BEACH CITY OF (1010005) buys surface water · local government · SC1010005 | 5,086 served |
| SULLIVANS ISLAND TOWN OF (1010003) buys surface water · local government · SC1010003 | 2,521 served |
Source: U.S. EPA Safe Drinking Water Information System (SDWIS), active community systems, . Look up any system's violations and test results with EPA's search using its ID.
About 1,078 people were held in Charleston County's jail, in Vera's latest figure (2024), or 388 per 100,000 residents ages 15–64. In 2019 it was about 1,060.
Source: Vera Institute of Justice, Incarceration Trends (built from federal Bureau of Justice Statistics jail surveys). Counties without their own jail, or that share one, may show no figure.
1 school district has its office in Charleston County. School taxes are usually the largest part of a property tax bill.
Spent $1.2 billion — $915.6 million to run schools, about $18,338 per student, plus $177.4 million on buildings and equipment. Money in: $777.3 million local (mostly property tax), $365.9 million state, $183.3 million federal. Long-term debt: $699.9 million.
Source: U.S. Census Bureau, 2023 Annual Survey of School System Finances. Districts are listed by the county of their main office; some serve neighboring counties too.
Source: County Health Rankings & Roadmaps 2025 (University of Wisconsin Population Health Institute), which gathers federal data (CDC, Census, and others); measures cover different recent years. Blank lines aren't reported for small counties.
Overall risk: Relatively High compared with other U.S. counties. FEMA estimates natural hazards cost Charleston County about $499.8 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Very High; social vulnerability: Relatively Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
339 bridges in Charleston County: 141 in good condition, 189 fair, and 9 poor (2.7%). “Poor” means a main part — the deck, the beams, or the supports — is rated 4 or lower on the federal 0–9 scale. It doesn't mean unsafe to drive; unsafe bridges are closed.
| I-26 over RR CSXT · built 1963 | 94,100 vehicles a day |
| SC 7 over ASHLEY RIVER · built 1953 | 47,800 vehicles a day |
| US 17 NB over ASHLEY RIVER · built 1961 | 38,250 vehicles a day |
| SC 703 over SHEM CREEK · built 1947 | 37,500 vehicles a day |
| S-10-97 over TIDAL STREAM · built 1972 | 18,100 vehicles a day |
| S-390/TOOGOODOO RD over SWINTON CREEK · built 1975 | 1,750 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $603.8 million of work in Charleston County in fiscal 2025, about $1,479 per resident — to the county, cities, schools, hospitals, nonprofits and others.
Source: USAspending.gov, grants by place of performance, fiscal 2025 (Oct. 2024 to Sept. 2025). Search it by county to see each award.
From Grants.gov: posted grants listing county governments as eligible, soonest deadline first; research-only and overseas programs left out; list updated 2026-10-13, refreshed weekly. 62 are open in all. Cities, towns, school districts and nonprofits have their own lists there.
Registration deadlines, early voting and polling places for South Carolina are on the federal site vote.gov, which links to the state's official election office.
The budget, property tax rates, audits, local officials and offices for Charleston County come from the county's own records, which we haven't gathered — not gathered, never hidden. See what a full county site looks like, or ask to have Charleston County built: brayden.ozark@gmail.com.
More of South Carolina: the state government and every county in South Carolina.
Nearby counties: Berkeley County (28 mi) · Dorchester County (33 mi) · Colleton County (42 mi) · Beaufort County (53 mi) · Georgetown County (57 mi) · Williamsburg County (58 mi).