The drainfield is the part of a septic system that actually fails, and it's the expensive part. We'll tell you honestly whether yours can be saved or needs replacing.
A drainfield is the buried network of trenches or chambers where effluent soaks into the soil. Most septic failures are drainfield failures. Whether yours can be repaired depends on why it failed: a field clogged by carryover from a neglected tank sometimes recovers, while one that has structurally failed or simply aged out has to be replaced. The EPA notes drainfields older than 25 to 30 years commonly lose effectiveness.
Almost all of it traces back to one of four causes.
The biggest one by far. When a tank isn't pumped on schedule, or a baffle fails, solids leave the tank and clog the soil around the trenches. Once the soil's pore space is sealed, it stops accepting effluent. This is largely irreversible, which is why routine pumping is the cheapest thing you'll ever do for your system.
More water going in than the field can process. Sometimes it's a growing household, sometimes a leaking fixture, sometimes a sump or downspout routed into the system. The field never gets a chance to drain and recover.
Roots into the lines, or crushing from vehicles and equipment driven over the field. Clemson names both as the leading causes of underground pipe damage in South Carolina systems.
Fields don't last forever. Past 25 to 30 years, reduced effectiveness is normal even on a well-maintained system.
Replacing a drainfield is a permitted job, not a maintenance call. In South Carolina you have to notify SCDES before replacing a system or its components and they determine whether a new permit is required. In Georgia, all replacements require permitting and a county board of health inspection before backfill.
The new field goes in the repair area, which is the reserve space South Carolina requires you to hold back when a system is first permitted, at least 50 percent of the original system size. If your property has that space and it's usable, replacement is relatively straightforward. If it doesn't, or if the reserve area has been built over, landscaped, or paved, we're into engineered design territory.
| Work | Typical range |
|---|---|
| Drainfield replacement | $X,XXX+ |
| Partial field repair or line replacement | $XXX-$X,XXX |
| Distribution box replacement | $XXX-$X,XXX |
| Engineered replacement field, difficult lot | $XX,XXX+ |
| Yard regrading after the work | Quoted per job |
What moves the number: soil type and how much field area the evaluation requires, whether the reserve area is usable, equipment access, depth, and whether the design has to be engineered. On Piedmont clay lots north and west of the Fall Line, the required footprint is larger, which pushes the cost up.
If your field is fifteen years old and clogged because the tank went unpumped for a decade, we'll usually tell you to replace it, because patching it means doing this again in two years. If it's five years old and the problem is a crushed line where a truck drove across it, that's a repair and we'll say so. We'd rather do the right job once than the wrong job twice.
Pumping a tank that keeps filling up isn't a repair, it's a subscription. We find what's actually wrong and fix that instead....
Learn more →Clay soil, a high water table, or not enough room for a standard drainfield. If your lot was turned down, this is usually the answer, and on...
Learn more →New builds, developments and full replacements. We handle every step, from soil evaluation and permitting through final inspection, so you e...
Learn more →Tell us about the property and what it's doing. We'll come look, tell you straight what it needs, and give you a number you can plan around.