Septic tank size by state / West South Central
Arkansas septic tank size
In Arkansas the minimum septic tank for a three-bedroom house is 1,000 gallons, rising to 1,250 gallons at four bedrooms. The figure comes from Rules Pertaining to Onsite Wastewater Systems (2024, effective Sept. 5, 2024), Section 10 and Appendix C. That matches the 1,000-gallon median of the 47 states listed here.
What the Arkansas rule says
The rule is Rules Pertaining to Onsite Wastewater Systems (2024, effective Sept. 5, 2024), Section 10 and Appendix C, administered by Arkansas Department of Health, Environmental Health Branch (Onsite Wastewater). In its own words:
Appendix C, Minimum Capacity of Septic Tanks (residential): 1, 2, and 3 bedrooms, 1000 gallons; next row, 1250 gallons. "Note: For each additional bedroom add 250 gallons." Section 10.1: "Garbage grinders are not recommended for standard onsite wastewater systems."
Source: Rules Pertaining to Onsite Wastewater Systems (2024, effective Sept. 5, 2024), Section 10 and Appendix C, read 2026-10-20.
- Arkansas does not recommend garbage grinders on standard systems; the table allows for ordinary household appliances.
- Above three bedrooms each bedroom adds 250 gallons. The rule's table prints its four-bedroom row with a '3'; read with the +250 note it is 1,250 gallons.
Arkansas minimum tank size by bedrooms
| Bedrooms | Minimum tank | Versus the median state |
|---|---|---|
| 1 | 1,000 gal | same |
| 2 | 1,000 gal | — |
| 3 | 1,000 gal | same |
| 4 | 1,250 gal | +50 |
| 5 | 1,500 gal | same |
| 6 | 1,750 gal | — |
The first step up comes at 4 bedrooms, from 1,000 to 1,250 gallons, and a six-bedroom house needs 1,750 gallons. Beyond the table the rule adds 250 gallons for each extra bedroom. These are minimums: the permit can call for more, and a bigger tank needs pumping less often.
How Arkansas compares with nearby states
Louisiana requires 1,000 gallons for three bedrooms; Oklahoma requires 1,000 gallons for three bedrooms; Texas requires 1,000 gallons for three bedrooms. 37 of the 47 states listed here share Arkansas's three-bedroom figure.
Before you size a tank in Arkansas
- Bedrooms, not people, set the size in most rules. Rooms that could be used as bedrooms are usually counted, so check how your permitting office counts a den or a finished basement.
- Garbage disposals, grinder or ejector pumps and large tubs change the answer in many states; the points above list Arkansas's adjustments.
- The tank is only half the system. The drainfield is sized separately from soil tests, and it is usually the bigger cost.
- A private well on the same lot has its own setbacks from the tank and field; the well pump and pressure tank calculators size the water side.
Figures are the state's minimum as written on 2026-10-20. Local health departments can require more; the permit issued for your property governs. See the methodology for how each state was read.