Septic System Installation in Sumter, SC

Where Sumter's city sewer ends and septic begins

The City of Sumter's Wastewater Division runs the city sewer and the Pocotaligo Wastewater Treatment Plant. The same division runs the Mayesville system, and the Town of Pinewood owns its own. Where no public sewer reaches, the Sumter 2040 plan says private septic systems are the only option.

The plan also steers where sewer goes next. It backs suburban building above two homes an acre only where water and sewer exist or can be added. In the rural planning area, it supports homes on lots of an acre or more. Public sewer will not be extended there for denser building, except within 500 feet of Mayesville and Pinewood.

Growth has moved west, away from downtown and toward Shaw Air Force Base. Many new subdivisions are annexed into the city to get its full range of services. Others still go in on septic. One 30-lot subdivision plan before the planning commission in January 2025 called for a septic system on each lot.

Sumter County soil and a high water table

The federal soil survey for Sumter County shows the problem in numbers. Its national rating calls about two thirds of the county's land very limited for septic drain fields. The reasons it cites most are slow water movement and a wet layer close to the surface. Rains, a poorly drained soil, covers more of the county than any other soil series.

In town, Swan Lake Iris Gardens began in 1927 on 30 acres of swamp. Under state rules, the standard trench system needs the wet layer at least 29 inches below the surface. On about half the county's land, the wet layer rises within 29 inches of the surface. Wetter lots may still fit one of the other designs in the same rules.

A soil map points the way, but a state inspector decides each lot with at least two soil borings. The soil's color shows how high the water rises in the wettest season. Ground soaked with wastewater over the drain field is one of the two clearest failure signs, the state says. That is where drain field repair starts.

Older homes and mobile home lots around Sumter

More than half the homes in Sumter County were built before 1990, Census figures show. About a third went up in the 1970s and 1980s. On a septic lot, a house from those years may still run its first tank and drain field. Broken baffles and crushed lines are septic system repair work, and a system past saving needs septic system replacement.

About one home in five across Sumter County is a mobile home, against about one in twenty inside the city. City-county permit records put mobile homes at about a quarter of the homes permitted in the county from 2013 on. Homes more than 20 years old may only be placed in the county, outside the city limits. Off the sewer, mobile home septic systems start with the state permit, before the home is set.

Who issues septic permits in Sumter County?

Septic permits come from the state, not the city or the county. The South Carolina Department of Environmental Services (SCDES), formerly DHEC, runs a regional septic office in Sumter. That office covers Sumter County and seven others, Clarendon and Lee among them. Applications go in online through the SCDES ePermitting portal, with a plat or deed for the land.

If the soil passes the site visit, the inspector issues a permit to construct, good for five years. We install the system to that permit and call SCDES to inspect it before it is covered. When the ground is too wet, SCDES may hold the soil evaluation until it dries out.

The rules also set the spacing. A septic system must sit at least 75 feet from a private well and 25 feet from a drainage ditch. The lot also needs a spare repair area half the size of the drain field. We call SC 811 before any machine digging, and 811 does not mark septic tanks or private lines.