Vermont · Vermont Wastewater System and Potable Water Supply Rules
Vermont DEC administers the program directly statewide, with no municipal permitting layer for wastewater.
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.
Glacial till over bedrock with ledge at shallow depth across much of the state, steep slopes, and seasonal high groundwater. Clay soils in the Champlain valley.
Conventional trenches where soil depth allows. Mounds and at-grade systems are common. Vermont permits innovative and alternative technologies through a specific approval pathway.
| Dwelling | Design flow | Minimum tank | With disposal |
|---|---|---|---|
| 1 bedroom | 280 gpd | 1,000 gal | 1,250 gal |
| 2 bedrooms | 280 gpd | 1,000 gal | 1,250 gal |
| 3 bedrooms | 420 gpd | 1,000 gal | 1,250 gal |
| 4 bedrooms | 560 gpd | 1,250 gal | 1,500 gal |
| 5 bedrooms | 700 gpd | 1,500 gal | 1,750 gal |
Vermont requires a licensed designer and issues a combined Wastewater System and Potable Water Supply Permit — the water supply and wastewater approvals are handled together, which differs from most states. Design flow is calculated at a lower rate per bedroom than the national norm.
The state sets a floor. These Vermont counties are where the largest septic populations sit, and where local requirements most often exceed it.
| County | What makes it different |
|---|---|
| Chittenden | Burlington area; clay soils and growth pressure |
| Rutland | Mixed valley and upland soils |
| Windsor | Rural with ledge and slope |
| Washington | Central Vermont hill sites |
| Addison | Champlain valley clay |
A three-bedroom home at 140 gallons per bedroom produces 420 gallons per day of design flow. On sandy loam that needs roughly 700 square feet of absorption area. On clay loam it rises to about 2,100 square feet, and on clay a conventional field is usually not permitted at all. Run your own soil class through the drainfield calculator.
No mandated statewide interval; designers commonly recommend three to four years. Use the pump schedule calculator to work out the interval for your tank size and household.
Regional labour and permit costs in Vermont run about 118% of the national baseline. Here is what typical installations land at for a three-bedroom home:
| System type | Typical installed cost in Vermont | When it applies |
|---|---|---|
| Conventional gravity | $10,600 – $18,900 | Good soil, adequate depth to water |
| Chamber system | $11,700 – $21,700 | Alternative to gravel trenches |
| Mound system | $20,100 – $39,700 | Shallow water table or thin soil |
| Aerobic treatment | $17,000 – $34,000 | Clay soil or small lots |
| Tank pump-out (service) | $380 – $770 | 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 Vermont Wastewater System and Potable Water Supply Rules. County and health district rules routinely exceed them, code text changes, and only Vermont DEC — Drinking Water and Groundwater Protection or your local health department can confirm what applies to your parcel.
Send your sizing numbers to installers who work under Vermont rules every day.