The short answer
The septic system you need is determined by your perc rate (how fast water moves through your soil) and your water table depth (how close groundwater sits to the surface). Until those are measured, anyone naming a system is guessing. Here are the five we install most often in CNY.
1. Conventional gravity system
What it is: Tank to distribution box to perforated pipe in a stone-filled trench. Effluent flows by gravity, soaks into native soil.
When it fits: Sandy loam, perc rate 5 to 30 minutes per inch, water table at least 4 ft below grade, no bedrock issues.
Pros: Cheapest option. No pumps, no electric. Simple. Long-lived (25 to 40 years).
Cons: Needs decent soil. Larger footprint than chamber systems.
Cost: $8,000 to $13,000
2. Chamber system (Infiltrator)
What it is: Same gravity flow as conventional, but plastic arch chambers replace the stone-and-pipe field.
When it fits: Same soil conditions as gravity, when you want a smaller footprint or the site is hard to access for stone trucks.
Pros: 40% less trench length than stone. Faster install. Easier on tight lots.
Cons: Slightly higher material cost. Same soil dependency as gravity.
Cost: $10,000 to $15,000
3. Pressure distribution
What it is: Tank to pump chamber. Effluent is pumped in measured doses through small-diameter pipe, distributed evenly across the field.
When it fits: Marginal soils (perc 30 to 60 min/inch), level lots where gravity won't distribute evenly, or sites where the field has to be uphill of the tank.
Pros: Even loading extends field life. Works on flat sites. Can go uphill.
Cons: Pump chamber adds cost. Needs dedicated electric circuit. Pump replacement every 8 to 12 years ($600 to $1,200).
Cost: $13,000 to $19,000
4. Engineered mound
What it is: A constructed sand mound built above grade, with effluent pumped into it. The mound IS the treatment field.
When it fits: High seasonal water table (mottling within 24 inches of surface), shallow bedrock, or clay soils that won't perc.
Pros: Lets you build on otherwise unsuitable sites. Standard solution for most lakefront and clay-bound CNY properties.
Cons: Most expensive option. Large visible footprint (looks like a long raised berm). Engineer's stamp required. Pump chamber required. Cannot drive or build over it.
Cost: $22,000 to $28,000
5. Aerobic treatment unit (ATU)
What it is: A small treatment plant in your yard. Air is pumped into the tank to grow bacteria that break down waste before it ever hits the soil.
When it fits: Failed perc with no mound option, sites near surface water (lakefront under 100 ft setback), small lots that can't fit a conventional field, or where the county requires advanced treatment.
Pros: Treats effluent to near-drinking-water quality before discharge. Works on sites that fail everything else. Compact.
Cons: Annual service contract required ($300 to $500/yr). Electric blower runs 24/7 ($15 to $30/month). Most complex system to maintain.
Cost: $15,000 to $24,000
Quick decision table
| Your situation | Likely system |
|---|---|
| New build, sandy soil, country lot | Gravity or chamber |
| Tight in-town lot, decent soil | Chamber |
| Field has to go uphill of tank | Pressure |
| Lakefront, high water table | Mound or ATU |
| Clay soil, failed perc | Mound or ATU |
| Old failed system, same site | Depends on what failed (see tank replacement) |
Don't pick the system. Pick the contractor who tests first.
Any contractor naming a system before they have a perc test on your specific lot is selling you what they want to install, not what your soil needs. We run the test, show you the result, and recommend the cheapest system that will actually work on your site.