Septic Replacement Design in Central NY
Failed field or tank? Find out if it is a repair in kind or needs a stamped design, which county permit applies, and whether grant money covers part of it.
Repair. Redesign. Permit.
When a failed septic system needs an engineer and when it does not.
Not always. NYS DOH Fact Sheet #1 says in kind or like for like replacement of components may not need a licensed design professional. A design professional is required when the absorption field is moved or extended to a spot not previously approved, when a new subsurface system goes in at the same location, or when the repair uses a raised system, mound, sand filter or other alternative or innovative design.
Yes, in the counties we checked. Cayuga County says repairs must be reviewed and accepted by the Health Department before the work is done. Cortland County charges $65 for a tank replacement or repair in kind and $200 for a sewage disposal permit. Onondaga County has an Application for Repair of Sewage Disposal System, and the owner agrees to call for an inspection before the work is covered.
Onondaga County's repair application has a line where the owner states they chose not to hire a design professional. The form says it is valid only where there is no change in total usage of the property, and the work must be inspected before it is covered.
The NYS DOH design handbook says required separation distances are sometimes impossible to meet when repairing or replacing a failing system. It says specific waivers are not required for replacement systems unless the health department or watershed runs its own replacement approval program, though health departments may choose to issue them. Cortland County's sanitary code says waivers are not required for replacement systems where the official recognizes the need to fix a health or nuisance condition.
The NYS Septic System Replacement Fund reimburses up to 50 percent of eligible costs, up to $10,000 per property, for systems within 250 feet of listed waterbodies in participating counties. Design costs are eligible in part, and new construction is not. The award has to be accepted before the owner hires the design professional.
The NYS DOH design handbook groups the causes into poor siting, design or construction; overloading; and maintenance. It lists items to check, including depth to high groundwater, soil percolation, septic tank baffles, distribution box condition, surface grading toward the field, trench depth and level, plumbing leaks, sump pump discharges and pumping records.
It varies by county. Cayuga County says plan approval may take up to 4 to 6 weeks. Madison County asks for alternative system plans at least 30 days before construction. Cortland County permits are valid for 12 months once issued.
In the Owasco Lake and Little Sodus Bay watersheds, yes: Cayuga County's repair application says a licensed Professional Engineer or Registered Architect must prepare the plans. Elsewhere in the county, its sanitary code lets contractors who have held a county business permit for at least three years perform site evaluations and plans.
Septic replacement design for a failed system
When a septic system in Central New York fails, the fix is either a repair in kind (same type, same spot) or a new design. The rules split on that line. A broken tank swapped for a new tank often needs only a county repair permit. A field that has to move, grow, or become a raised bed or mound needs a stamped design from a licensed Professional Engineer and county approval before work starts.
This page covers the design and permit side of a replacement. For the install side in Syracuse, see septic system replacement.
Repair in kind vs. a new design: the state rule
NYS DOH Fact Sheet #1, "Need for Licensed Design Professionals," reviewed with the State Education Department, draws the line this way:
- In kind or like for like repair or replacement of components may not require a licensed design professional.
- Relocating or extending an absorption field to a location not previously approved for it does require a licensed design professional.
- A new subsurface treatment system at the same location requires a licensed design professional.
- An alternative system (raised system, mound or sand filter) or an innovative design or technology requires a licensed design professional.
The same fact sheet says local governments, watershed agencies and other agencies may add their own rules. In Central New York several of them do.
What each county asks for on a replacement
Onondaga County. The county's Application for Repair of Sewage Disposal System lets the owner state they chose not to hire a design professional. The form is valid only where there is no change in total usage of the property. The owner agrees to contact the Division of Environmental Health for an inspection before the work is covered. The county fee page lists a $62 repair inspection fee. A replacement that changes use, adds bedrooms or needs an engineered system goes through plan review instead: $310 for systems under 1,000 gallons per day under Local Law 11 of 2025. In the Skaneateles Lake watershed, 10 NYCRR 131.1 requires any alteration, addition or repair to conform to Appendix 75-A, with notice to the health department and the City of Syracuse, and every site and soil appraisal witnessed by a City watershed inspector.
Cayuga County (8 Dill St., Auburn). Repairs must be reviewed and accepted by the Health Department before the work is done. The owner or contractor may dig up parts of the system to diagnose the problem before getting approval. The Application to Modify/Replace an Existing Septic System (rev. 1/7/2025) carries a $100 review fee for conventional trench systems and $150 for other types. A tank-only replacement has no fee. In the Owasco Lake and Little Sodus Bay watersheds, a licensed PE or Registered Architect must prepare the plans.
Cortland County (60 Central Ave., Cortland). An engineer design is required for all replacement systems, full or leach field only. An engineer is not needed for a tank replacement only. The 2026 fee schedule lists $65 for a tank replacement or repair in kind and $200 for a sewage disposal permit. The sanitary code says no part of a system may be covered until a New York licensed PE inspects it.
Oswego County (70 Bunner St., Oswego). New residential systems must be designed by a licensed professional engineer or architect, and plans are reviewed for $125 under the 2026 schedule. Under the county's septic replacement grant program, replacements must be approved by the Health Department, designed by a licensed engineer, and covered by a local building permit.
Oneida County (185 Genesee St., Utica). Under the county's replacement funding program, all replacements and upgrades must be approved by the Oneida County Health Department, designed by a licensed engineer, and approved by local codes. The county plan review schedule lists $500 for an individual sewage system.
Madison County (138 N. Court St., Wampsville). The county reviews alternative system designs and asks for at least 2 copies of an engineer's design at least 30 days before construction, with a $125 review and inspection fee. Ordinary systems are permitted by the town. The Town of Madison, for example, requires a code enforcement permit to install or replace a septic system and says a New York PE must design and certify the plans.
Replacement vs. new construction: what changes
| Issue | New construction | Replacement of a failing system |
|---|---|---|
| Design standard | Appendix 75-A is the minimum statewide standard for all new residential systems | Handbook: separation distances are sometimes impossible to meet, so well and site data are weighed before any reduction |
| Design flow | 110 gallons per day per bedroom | Handbook Table 1: 130 gpd per bedroom with pre-1994 fixtures, 150 gpd with pre-1980 fixtures |
| Setbacks the lot cannot meet | Needs a specific waiver | Handbook: specific waivers not required unless the health department or watershed has a replacement approval program |
| Grant eligibility | Not eligible for the State Septic System Replacement Fund | Eligible within 250 feet of listed waterbodies |
The handbook is plain that a replacement still needs good judgment on wells. It says that when separation distances cannot be met, the well depth, casing depth, grouting, water quality, depth to the aquifer and local geology should all be weighed before reducing a distance. It also warns that a "created" hardship, like tearing down a house known to have a substandard system without talking to the health department first, is at the owner's risk.
How a replacement design works
- Find out why it failed. Handbook Table 11 lists what to evaluate: perc retest, unsaturated soil depth, depth to high groundwater, surface grading toward the field, daily flow, tank baffles and size, field size, distribution box, trench depth and level, plumbing leaks, sump pump discharges, water treatment backwash, garbage grinder use, home business discharges, and pumping records.
- Test the new area. If the field is moving or being rebuilt, a deep hole test and perc tests are run in the new area, plus the reserve area where there is room.
- Pick the system the site supports. Old fields often failed because the soil depth to groundwater or rock was never there. If the new area has under 4 feet of useable soil, the design moves to shallow trenches, a raised system, a mound or enhanced treatment.
- Fix the water problems. Handbook Table 11 lists surface water diversion (regrading, filling, ditching) and groundwater control such as curtain drains as corrections. Roof, footing, garage and cellar drainage must be kept out of the system under Appendix 75-A.
- Stamp and submit. The PE prepares the plan and Backwell files it with the county, the town, or the watershed agency that has jurisdiction.
- Install and inspect before backfill. Inspection steps vary by county. See the septic engineering process page.
Signs the field, not the tank, is the problem
Sewage surfacing over the field, soggy ground in dry weather and backups that come back right after a pump-out usually point at the absorption area. The handbook's failure table splits causes into siting, design and construction; overloading; and maintenance. A tank that was never pumped can push solids into the field and clog the soil, so a new tank alone may not fix a field that is already sealed. See septic failing or backing up.
Grant money for replacements
The NYS Septic System Replacement Fund, run by DEC with the Environmental Facilities Corporation through participating counties, reimburses up to 50 percent of eligible costs, up to $10,000 per property (DEC program outline, June 2026). The property must be within 250 feet of an eligible waterbody. Design costs are eligible when limited to the work needed for an approved design, including site investigation, as-built drawings and inspections. Permit fees, sales tax and pump-outs are not. The owner must accept the award letter before hiring the design professional, so apply first.
DEC's 2026 eligible waterbody lists include Skaneateles, Otisco and Owasco lakes, Jamesville Reservoir, Cazenovia Lake, the Lake Ontario shoreline in Oswego and Cayuga counties, and Hinckley, Delta and Rome reservoirs in Oneida County. Oneida County says its program ends March 31, 2027.
Timeline
A tank-only swap with a county repair permit is the short path. A relocated or engineered field adds soil testing, design and plan review. Cayuga County says approval may take up to 4 to 6 weeks, and Madison County wants alternative system plans 30 days before construction. The DOH handbook does not allow perc testing in frozen ground, so a field that fails in winter may not be tested until the frost is out.
What Backwell does
Backwell digs the test pits, coordinates the stamped replacement design, files the repair application or plan review, and installs the approved system. The cost side is on the septic engineer cost page.
Designs are prepared and stamped by a New York licensed Professional Engineer (PE). Backwell coordinates the design, the health department submittal, and the install.
Sources
- NYS DOH, Residential Onsite Wastewater Treatment Systems Design Handbook (includes Appendix 75-A and Fact Sheet #1)
- NYS DOH, 10 NYCRR Appendix 75-A, Wastewater Treatment Standards: Residential Onsite Systems
- Onondaga County, Application for Repair of Sewage Disposal System
- Onondaga County Health Department, Fee Schedule
- Onondaga County Local Law 11 of 2025, Health Department fees (effective 1/1/2026)
- 10 NYCRR 131.1, Skaneateles Lake watershed rules and regulations
- Cayuga County Health Department, Instructions for Modifying or Repairing a Septic System
- Cayuga County, Application to Modify/Replace an Existing Septic System (rev. 1/7/2025)
- Cayuga County Sanitary Code
- Cortland County Health Department, Sewage Systems
- Cortland County Health Department, Fee Schedule effective April 1, 2026
- Cortland County Sanitary Code (April 1, 2026)
- Oswego County Health Department, Water Supply Protection
- Oswego County Health Department, 2026 Plan Review Fee Schedule
- Oswego County, Septic System Replacement Program application
- Oneida County Health Department, Septic System Replacement Funding
- Oneida County Health Department, Plan Review Fee Schedule (rev. 3/2022)
- Madison County Public Health, Water and Septic: Individual Systems
- Madison County, Alternative Household Wastewater Treatment System Application
- Town of Madison, building and septic fee schedule
- NYS DEC, State Septic System Replacement Fund program outline (June 2026)
- NYS DEC, Septic System Replacement Fund participating counties and priority waterbodies
