Septic tank size by state / South Atlantic
Virginia septic tank size
In Virginia the minimum septic tank for a three-bedroom house is 900 gallons, rising to 1,200 gallons at four bedrooms. The figure comes from 12VAC5-610-815 (Septic tank design), Table 5.2. That is 100 gallons less than the 1,000-gallon median of the 47 states listed here.
What the Virginia rule says
The rule is 12VAC5-610-815 (Septic tank design), Table 5.2, administered by Virginia Department of Health (VDH), Office of Environmental Health Services. In its own words:
The minimum hydraulic detention time shall be 48 hours based on daily design flow. In no case shall the septic tank capacity be less than 750 gallons. Table 5.2 contains the minimum required septic tank capacities for dwelling units. Table 5.2. Septic Tank Capacities for Dwelling Units. No. of Bedrooms / Approximate Tank Volume in Gallons: 1 - 750; 2 - 750; 3 - 900; 4 - 1200; 5 - 1500
Source: 12VAC5-610-815 (Septic tank design), Table 5.2, read 2026-10-20.
- Virginia's table is labelled approximate: the governing rule is 48 hours of design flow, with a 750-gallon floor.
- The table stops at five bedrooms.
Virginia minimum tank size by bedrooms
| Bedrooms | Minimum tank | Versus the median state |
|---|---|---|
| 1 | 750 gal | −250 |
| 2 | 750 gal | — |
| 3 | 900 gal | −100 |
| 4 | 1,200 gal | same |
| 5 | 1,500 gal | same |
| 6 | See note | — |
Above 5 bedrooms the rule sizes the tank for 48 hours of design flow; the table stops at 5.
The first step up comes at 3 bedrooms, from 750 to 900 gallons. These are minimums: the permit can call for more, and a bigger tank needs pumping less often.
How Virginia compares with nearby states
Delaware requires 1,000 gallons for three bedrooms; Florida requires 900 gallons for three bedrooms; Georgia requires 1,000 gallons for three bedrooms; Maryland requires 1,000 gallons for three bedrooms; North Carolina requires 1,000 gallons for three bedrooms; South Carolina requires 1,000 gallons for three bedrooms; West Virginia requires 1,000 gallons for three bedrooms. 4 of the 47 states listed here share Virginia's three-bedroom figure.
Before you size a tank in Virginia
- 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 Virginia'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.