Oklahoma · Oklahoma Administrative Code Title 252
Oklahoma DEQ administers the program directly through its environmental complaints and local services division.
Minimum tank
One to three bedroom dwelling.
Design flow
Held two days for settling.
Cost index
Regional labour and permits.
Sets the design flow and the legal minimum.
Code sizes on bedrooms, not people.
Used to size the matching drainfield. Unsure? Sandy loam is the common default.
Red clay across central Oklahoma with slow percolation, sandy soils in parts of the west and along river valleys, and rocky ground in the east through the Ouachitas and Ozarks.
Conventional trenches on suitable soil. Aerobic treatment units with spray irrigation are extremely common in Oklahoma clay areas — the state has one of the higher rates of aerobic system use in the country. Lagoons appear on rural acreages.
| Dwelling | Design flow | Minimum tank | With disposal |
|---|---|---|---|
| 1 bedroom | 300 gpd | 1,000 gal | 1,250 gal |
| 2 bedrooms | 300 gpd | 1,000 gal | 1,250 gal |
| 3 bedrooms | 450 gpd | 1,000 gal | 1,250 gal |
| 4 bedrooms | 600 gpd | 1,250 gal | 1,500 gal |
| 5 bedrooms | 750 gpd | 1,500 gal | 1,750 gal |
Oklahoma DEQ licenses installers and requires soil profile evaluation. Aerobic spray systems require a maintenance contract with a certified service provider for the first two years, and continuing service thereafter.
The state sets a floor. These Oklahoma counties are where the largest septic populations sit, and where local requirements most often exceed it.
| County | What makes it different |
|---|---|
| Oklahoma | OKC fringe; red clay |
| Tulsa | Eastern metro with mixed soils |
| Cleveland | Norman area, heavy septic population |
| Canadian | Fast suburban growth west of OKC |
| Rogers | Rural acreage development |
| Wagoner | Lake area development |
A three-bedroom home at 150 gallons per bedroom produces 450 gallons per day of design flow. On sandy loam that needs roughly 750 square feet of absorption area. On clay loam it rises to about 2,250 square feet, and on clay a conventional field is usually not permitted at all. Run your own soil class through the drainfield calculator.
Aerobic units require a service contract and periodic reporting. Use the pump schedule calculator to work out the interval for your tank size and household.
Regional labour and permit costs in Oklahoma run about 88% of the national baseline. Here is what typical installations land at for a three-bedroom home:
| System type | Typical installed cost in Oklahoma | When it applies |
|---|---|---|
| Conventional gravity | $7,900 – $14,100 | Good soil, adequate depth to water |
| Chamber system | $8,700 – $16,200 | Alternative to gravel trenches |
| Mound system | $15,000 – $29,600 | Shallow water table or thin soil |
| Aerobic treatment | $12,600 – $25,400 | Clay soil or small lots |
| Tank pump-out (service) | $280 – $570 | Every 3–5 years |
Replacing an existing system costs more than these figures — old-system removal and re-permitting add to every line. The replacement cost calculator covers that case, and the cost estimator adjusts all of the above for your bedroom count and soil.
Verify before you build. The figures above are state minimums compiled for planning, drawn from Oklahoma Administrative Code Title 252, Chapter 641, Individual and Small Public On-Site Sewage Disposal Systems. County and health district rules routinely exceed them, code text changes, and only Oklahoma DEQ — Individual Sewage Disposal or your local health department can confirm what applies to your parcel.
Send your sizing numbers to installers who work under Oklahoma rules every day.