How Much Does Drain Field Repair Cost in South Carolina?

A targeted drain field repair in South Carolina costs about $800 to $3,500. A full drain field replacement costs about $6,000 to $15,000, and a mound system can pass $20,000. Those figures come from a South Carolina cost guide published in April 2026. National cost guides show similar spreads.

Where your job lands depends on what failed and how high the water table rises at your lot. These are market numbers, not our price list. Need drain field repair around Summerton? We look at the field first and put the quote in writing.

What does drain field repair cost compared with replacement?

The table splits the work the way the cost guides do. Some guides say leach field instead of drain field, and it is the same part.

The national column spans four national guides updated between January 2025 and June 2026. They name the same cost drivers: how much of the field failed, the soil, site access and the permit. One national guide adds about $1,500 to $5,000 when the tank is replaced at the same time.

What are the signs of a failed drain field?

The South Carolina Department of Environmental Services (SCDES, formerly DHEC) names the two most obvious signs of septic failure. Sewage backs up into the house, or the ground over the drain field stays soaked with wastewater. EPA septic guidance lists more warning signs:

• Tubs and sinks drain slowly.
• Pipes gurgle when water goes down.
• Damp spots or standing water sit over the field.
• Sewage smells hang near the tank or the field.
• Bright green, spongy grass grows over the field, even in dry weather.

SCDES adds that grass outlining the field points to a leak or another problem. A wet stripe over one line can point to the distribution box rather than the whole field. SCDES lists missed maintenance as a likely cause, since solids built up in the tank get forced into the field. Pumping is a job for a pumping company, and we repair and replace the field.

Why do Coastal Plain soils and water tables decide the fix?

A conventional drain field needs dry soil under it. The state rule requires the zone of saturation, where groundwater soaks the soil, to sit at least 29 inches down. SCDES reads that depth from soil color, which shows how high the water table climbs in the wettest months.

That is a hard target in the low, flat ground around Lake Marion. Federal soil survey data show a seasonal water table within 29 inches on about two-thirds of Clarendon County’s land. SCDES still decides each lot from its own borings.

Lynchburg loamy sand, the county’s most widespread mapped soil, can be wet 6 inches down from November through April. Fuquay fine sand, nearly as common, keeps its wet layer about 4 feet down.

Sand helps in one way. The state’s sizing table lets sandy soil take about 1 gallon a day per square foot of trench bottom. Heavy clay may take a tenth of that, so clay needs a much bigger field.

When the water sits high, the rule turns to other designs. Shallow trenches under a fill cap can work with saturation 12 inches down. A mounded system can work with it 6 inches down, on sandy or loamy topsoil. Each step adds fill and cost.

The same South Carolina guide shows the spread. It prices a full replacement at $3,000 to $8,000 in the Sandhills and Midlands. In the Lowcountry, where it says most replacements need a mound or a treatment unit, it lists $10,000 to $22,000.

What does the state repair permit involve?

Septic work in South Carolina follows Regulation 61-56, which SCDES enforces. Before a drain field is relocated or replaced, the rule says the owner must notify SCDES. The agency then decides whether the job needs a permit.

When it does, the permit works like one for a new system. An evaluator checks the soil at the site. SCDES says backhoe pits are not required below the Fall Line, in the Coastal Plain. Our guide to the state soil evaluation and permit walks through each step.

The rule sets a $150 fee to evaluate a site for a permit. Ask the regional office whether your repair needs one. Wet ground can push an evaluation back until the soil dries. Permitted work gets a final inspection before it is covered.

Two more rules shape a repair. Your county or town decides whether public sewer is available to a lot. Where it is, the rule does not allow a failing system to be repaired or replaced.

A permit under today’s rule also marks a repair area at least half the size of the original system. Keep buildings and paving off that ground.

SCDES’s Sumter office handles Clarendon, Sumter, Kershaw and Lee counties. Orangeburg County goes to the Orangeburg office. Berkeley and Dorchester go to the Charleston office, and Florence and Williamsburg to the Florence office.

When is a repair enough, and when does the field need replacing?

A repair fits when one part failed and the soil still takes water. A crushed line or a cracked distribution box can be fixed in place. Roots in one trench may need only that line replaced. Those jobs sit at the low end of the table.

Replacement fits when the soil itself stops taking water. EPA guidance says solids pushed from the tank thicken the biomat, a bacteria layer on the trench bottom and sides. Flood silt can clog a field too, and SCDES says a silted field may need a new system.

A house can also outgrow its field. SCDES sizes a field at about 120 gallons a day per bedroom. A three-bedroom home needs room for about 360 gallons a day. More people than the design allows can push a field to failure.

Trouble at the tank, such as broken baffles or lids, is septic system repair work. When the tank and the field both have to go, the job becomes a full septic system replacement.

How do you get a firm number for your drain field?

Every field fails for its own reasons, so a firm number starts with a look at the ground. We find what failed and match the fix to your soil. Then we put the quote in writing.

See how our drain field repair work runs, or call or text (803) 478-2620 for a free estimate. Summerton sits at the center of our service area. The area reaches about 50 miles around Summerton, on the east side of South Carolina.