Kentucky · 902 KAR 10:085
Septic system requirements in Kentucky
Tank sizes, drainfield rules, setbacks, permits, and real costs — pulled from Kentucky's own code rather than a national average.
- 3-bedroom tank
- 1,000 gal
- Design flow
- 110 gpd/BR
- Typical install
- $6,500–$17,000
- Permit fee
- $150–$500
- Well setback
- 70 ft
- Permitted by
- County / local
Septic tank sizes required in Kentucky
Kentucky sizes systems on a design flow of 110 gallons per day per bedroom. The tank must meet both the bedroom table below and a 2× daily-flow detention requirement — whichever produces the larger number governs.
| Bedrooms | Design flow | Code minimum | Recommended | With garbage disposal |
|---|---|---|---|---|
| 1 bedroom | 110 gpd | 1,000 gal | 1,000 gal | 1,250 gal |
| 2 bedrooms | 220 gpd | 1,000 gal | 1,000 gal | 1,250 gal |
| 3 bedrooms | 330 gpd | 1,000 gal | 1,000 gal | 1,250 gal |
| 4 bedrooms | 440 gpd | 1,250 gal | 1,250 gal | 1,563 gal |
| 5 bedrooms | 550 gpd | 1,500 gal | 1,500 gal | 1,875 gal |
| 6 bedrooms | 660 gpd | 1,750 gal | 2,000 gal | 2,188 gal |
Source: 902 KAR 10:085. The recommended column rounds the governing requirement up to a tank size manufacturers actually stock.Run your own numbers →
Drainfield size and cost by soil type
For a three-bedroom home in Kentucky at 330 gpd. This single table explains most of the variation between quotes — the area scales inversely with how fast your soil accepts water, and the drainfield is the largest line item in the job.
| Soil | Loading rate | Absorption area | With reserve | Typical total install |
|---|---|---|---|---|
| Medium sand | 0.8 gpd/ft² | 413 ft² | 826 ft² | $8,900 |
| Sandy loam | 0.5 gpd/ft² | 660 ft² | 1,320 ft² | $10,900 |
| Loam | 0.4 gpd/ft² | 825 ft² | 1,650 ft² | $12,300 |
| Silt loam | 0.3 gpd/ft² | 1,100 ft² | 2,200 ft² | $14,500 |
| Clay loam | 0.2 gpd/ft² | 1,650 ft² | 3,300 ft² | $18,900 |
Estimates use Kentucky's cost index of 0.90× the national average. Build a line-item estimate →
Permits and who issues them
Local health departments issue permits under 902 KAR 10:085, the statewide on-site sewage rule administered by the Department for Public Health.
| Permit required | Yes |
|---|---|
| Typical fee | $150 – $500 |
| Soil evaluation | Required before permit |
| Licensed installer | Required |
| Turnaround | 2–5 weeks |
| Ongoing inspection | Not mandated statewide |
| Reserve area | 100% replacement area required |
Minimum setback distances
Measured horizontally from the drainfield unless noted. Local rules are frequently stricter, and on a small lot these numbers — not the soil — often decide the layout.
| Private water well | 70 ft |
|---|---|
| Well (septic tank) | 50 ft |
| Property line | 5 ft |
| Surface water | 50 ft |
| Building foundation | 10 ft |
Regulatory contact
Kentucky Department for Public Health — Onsite Sewage Program
www.chfs.ky.gov · 502-564-4856
What makes septic hard in Kentucky
Kentucky has some of the most extensive karst terrain in the country. Sinkholes, caves, and losing streams create direct routes to groundwater and severely restrict siting.
Eastern Kentucky mountain hollows offer steep slopes and almost no usable soil depth.
Bluegrass region soils sit on limestone with shallow, rocky profiles.
Things that catch people out
- Kentucky publishes explicit with-and-without garbage disposal tank tables — a disposal adds 250 gallons of required capacity.
- The well setback is 70 feet, an unusual figure that catches designers used to the 50 or 100 foot norms.
Kentucky septic questions
What size septic tank do I need in Kentucky?
A three-bedroom home in Kentucky requires a minimum 1,000 gallon tank under 902 KAR 10:085. Design flow is 110 gallons per day per bedroom, and the tank must also hold 2 times daily flow, so the practical recommendation is 1,000 gallons.
Do I need a permit for a septic system in Kentucky?
Yes. Local health departments issue permits under 902 KAR 10:085, the statewide on-site sewage rule administered by the Department for Public Health. Fees typically run $150 to $500, with a turnaround of about 2–5 weeks. A soil evaluation or percolation test is required before a permit is issued.
How much does a septic system cost in Kentucky?
A conventional system for a three-bedroom home typically runs $6,500 to $17,000 installed. Soil quality moves this more than anything else — on tight clay requiring a mound, budget two to three times the low end.
How far must a Kentucky drainfield be from a well?
70 feet from a private water well, with the septic tank itself allowed at 50 feet. Local rules can be stricter.
Sources
Every figure on this page traces to one of these documents.
- 902 KAR 10:085 — Kentucky on-site sewage disposal systems · verified 2026-09-18
- 902 KAR 10:085 Table 2 — Minimum septic tank capacities · verified 2026-09-18