Savannah is one of America's most celebrated historic cities, but beneath the Spanish moss and antebellum squares lies some of the most challenging septic terrain on the East Coast. Chatham County's flat Coastal Plain topography, sandy soils, and a water table that hovers close to the surface throughout much of the county make on-site septic installation complex and costly. While the historic core of Savannah is served by municipal sewer, the fast-growing suburban and exurban communities of unincorporated Chatham County, Pooler, Bloomingdale, and Garden City rely on private systems. Coastal development pressure, combined with strict environmental protections for Savannah's tidal marshes and estuaries, means septic system design and permitting in this area involves multiple regulatory agencies and demands careful site evaluation.
Soil Conditions
Lakeland and Troup soil series — deep, excessively drained fine sands with percolation rates of 2–8 minutes per inch. The Coastal Plain geology produces soils that drain extremely fast, but the shallow depth to the seasonal high water table is the primary constraint for conventional drain field placement in most of Chatham County.
The dominant Lakeland series soils are fine sands with negligible clay — fast-draining but with no treatment capacity for pathogens when the water table rises within 18 inches of the drain field. Georgia requires a minimum of 18 inches of unsaturated soil above SHWT for conventional drain fields; much of low-lying Chatham County fails this test during wet seasons. Troup series soils on slight rises are preferred for conventional systems. In transitional areas near the maritime forest, Leon series soils with a spodic horizon (cemented sand layer) can create a confining layer that mimics a high water table effect even in drier months.
Water Table: Seasonal high water table (SHWT) is a critical factor in Savannah — in much of Chatham County it ranges from 12 to 24 inches below the surface during winter and spring wet seasons, and tidal influence near the marshes and rivers can push it even shallower. Even in drier summer months, SHWT rarely exceeds 36 inches in low-lying coastal areas.
Local Regulations
Chatham County Environmental Health administers GA DPH on-site sewage rules with additional coastal overlays. Properties within 50 feet of a marsh, wetland, or tidal creek require DNR Coastal Resources Division review. The Georgia Coastal Marshlands Protection Act restricts any fill or construction in jurisdictional marshlands. For new subdivisions near the coast, engineered low-pressure dose (LPD) systems or drip irrigation systems are frequently required to manage effluent at the shallow seasonal water table depths typical of Chatham County.
The Chatham County Environmental Health Division issues all on-site sewage permits under Georgia DPH authority. Due to the coastal geography and tidal influence, Chatham County applies strict additional review for properties near marshes, wetlands, and tidal creeks — often triggering coordination with the Georgia DNR Coastal Resources Division and the Army Corps of Engineers for wetland delineation. Permit fees run $300–$500 for standard evaluations. Historic district properties in the City of Savannah are almost entirely on municipal sewer, but outer Chatham County and unincorporated areas rely heavily on septic. SHWT assessments are mandatory for all permits.