Pennsylvania · Title 25 Pennsylvania Code Chapter 73
Pennsylvania DEP writes Chapter 73 and municipalities administer it through a Sewage Enforcement Officer, under Act 537 planning.
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.
Limestone valleys with karst in the centre and southeast, shale and sandstone ridges, glaciated till in the northwest, and shallow rock across much of the state. Perched water tables are common.
Conventional trenches where soil depth allows. Elevated sand mounds are extremely common in Pennsylvania because of shallow limiting zones, and at-grade beds and drip irrigation are used on constrained sites.
| 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 |
Pennsylvania's Sewage Enforcement Officer is the key figure — a certified individual employed by or contracted to the municipality, who performs soil testing, reviews the design and issues the permit. Act 537 planning also governs whether a lot can be served at all.
The state sets a floor. These Pennsylvania counties are where the largest septic populations sit, and where local requirements most often exceed it.
| County | What makes it different |
|---|---|
| Chester | Limestone valleys with karst, high land values |
| Bucks | Suburban development, mixed soils |
| Lancaster | Limestone and karst, agricultural setting |
| York | Growth on shale and limestone |
| Monroe | Poconos; shallow rock, seasonal homes |
| Westmoreland | Western Pennsylvania till and shale |
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.
Many municipalities have adopted mandatory pumping ordinances on a three-year cycle. Use the pump schedule calculator to work out the interval for your tank size and household.
Regional labour and permit costs in Pennsylvania run about 108% of the national baseline. Here is what typical installations land at for a three-bedroom home:
| System type | Typical installed cost in Pennsylvania | When it applies |
|---|---|---|
| Conventional gravity | $9,700 – $17,300 | Good soil, adequate depth to water |
| Chamber system | $10,700 – $19,900 | Alternative to gravel trenches |
| Mound system | $18,400 – $36,300 | Shallow water table or thin soil |
| Aerobic treatment | $15,500 – $31,100 | Clay soil or small lots |
| Tank pump-out (service) | $350 – $700 | 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 Title 25 Pennsylvania Code Chapter 73, Standards for Onlot Sewage Treatment Facilities. County and health district rules routinely exceed them, code text changes, and only Pennsylvania DEP — Sewage Facilities Program or your local health department can confirm what applies to your parcel.
Send your sizing numbers to installers who work under Pennsylvania rules every day.