Your property failed the perc test – or the county says you need an engineered system. That does not mean you cannot build. Septic Tank Guru provides engineered septic system design for properties across Metro Atlanta with difficult soil, steep slopes, high water tables, and tight lots. We work with licensed Professional Engineers and certified soil classifiers to produce county-ready drawings in 7-10 business days – then we build the system after approval. One contractor from design to final inspection. See our full range of septic services across Metro Atlanta or call for a free engineering consultation.
Georgia-licensed Professional Engineers produce sealed drawings that your county will accept.
Serving for over 13 years.
We design the system and install it. No handoff between firms, no finger-pointing if something does not match.
Georgia DPH Rule 511-3-1 allows conventional gravity systems when the soil, slope, and lot size all pass standard requirements. When any of those fail, you need an engineered septic design. Here are the most common reasons Metro Atlanta properties require engineering:
Metro Atlanta’s Piedmont red clay dominates Fulton, Gwinnett, Cobb, and DeKalb counties. When a perc test shows drainage rates below the minimum – common on properties along Peachtree Industrial Boulevard, in Buckhead, and across South Forsyth – a conventional drainfield will not work. An engineered system design uses alternative dispersal methods that work with the soil you have, not against it. If your soil testing and septic permit results came back marginal, call us before assuming you cannot build. For a detailed breakdown of what that initial test costs across each county, see perc test costs in Metro Atlanta counties.
A failed perc test is the single most common reason properties in Metro Atlanta need an engineered design. If the soil classifier report shows your lot cannot support a conventional gravity drainfield, you still have options – mound systems, LPP, drip dispersal, and ATUs are all engineered alternatives designed for exactly this situation. We walk through every option with costs and timelines in our guide to what to do when your soil fails the perc test in Metro Atlanta.
Properties in Gwinnett County near the Chattahoochee corridor, low-lying areas of Forsyth County around Lake Lanier, and floodplain-adjacent lots across DeKalb County often have seasonal water tables too high for gravity drainfields. Engineered mound systems or low-pressure pipe designs solve this by raising the treatment zone above the water table.
Lots along the Chattahoochee hills, ridgeline properties in North Fulton, and sloped parcels in Forsyth County frequently exceed the maximum grade for standard trenches. Pressure-dosed and drip dispersal systems distribute effluent evenly across the contour instead of fighting gravity.
When you replace a failed system on an existing lot, the county often requires a new design review. If the original system was permitted decades ago under older standards, the replacement may need to meet current code – which can trigger an engineered design requirement. If your existing system is showing signs of needing full replacement, start with a call so we can assess whether engineering is needed before you commit to a path.
Not sure if your property needs engineering? Call 404-694-3060 and describe your situation. We can usually tell you over the phone whether a conventional system or an engineered design is the right starting point.
The right system depends on your soil, slope, water table, and lot size. Here are the four engineered system types we design and install across Metro Atlanta.
Built for high water tables or shallow bedrock. Effluent is pumped into a raised sand-and-gravel mound that provides the vertical separation your soil cannot. Common on properties near Buckhead, South Forsyth, and Gwinnett County floodplain-adjacent lots. Our drainfield installation service handles the full mound construction after design approval. Installed cost for mound systems in Metro Atlanta typically runs $12,000-$25,000 depending on fill volume and site access. Mound systems require ongoing monitoring and regular septic maintenance to keep the dosing pump and distribution network performing correctly.
ATUs aerate wastewater to produce cleaner effluent before it reaches the dispersal field. Required on tight lots or environmentally sensitive areas where a standard septic tank cannot provide enough treatment. ATU systems need ongoing maintenance – quarterly inspections and annual service – so choosing a reliable pumping and maintenance provider is critical for long-term performance. Many properties along the GA-400 corridor and in older Cobb County subdivisions near the Chattahoochee use ATU-based designs. Installed cost: $10,000-$20,000.
Sewage surfacing in your yard, backup into the house, or a system that stopped working overnight – we dispatch emergency drainfield repair the same day across the Atlanta metro area. Call now. We answer and dispatch – no callback window, no hold queue.
Emergency service available in: Acworth, Vinings, Buckhead, Stone Mountain, Lilburn, Douglasville, Fayetteville, Jonesboro, Smyrna, Decatur, Sandy Springs + all Atlanta metro areas.
Engineered septic design costs depend on site complexity, system type, and flow volume. Here are typical ranges for engineering and design fees in Metro Atlanta – installation costs are separate.
| Service | Typical Cost Range | What It Covers |
|---|---|---|
| Standard residential system design | $800 – $1,500 | Conventional gravity system on acceptable soil – site plan, sizing, county submission |
| Engineered alternative system design (mound, LPP, drip, ATU) | $1,500 – $3,000 | Hydraulic calculations, PE-sealed drawings, pump selection, county coordination |
| Complex or commercial design (flows over 2,000 gpd) | $3,000 – $7,500+ | Multiple design iterations, advanced pretreatment, modeling, multi-agency coordination |
| Third-party soil survey (not a Septic Tank Guru fee) | $400 – $800 | Certified soil classifier evaluation – required by Georgia DPH for every new system |
| Mound system – installed | $12,000 – $25,000 | Engineered fill, pump station, pressure distribution, final inspection |
| ATU system – installed | $10,000 – $20,000 | Aerobic treatment unit, dispersal field, controls, startup |
| LPP system – installed | $8,000 – $15,000 | Low-pressure pipe network, dosing tank, pump, distribution laterals |
| Drip dispersal system – installed | $15,000 – $30,000 | Filtration, drip tubing, pressure-compensating emitters, flush system |
Every property is different. Call 404-694-3060 to discuss your soil report and get a site-specific quote. If you are still in the early stages and need a septic inspection to understand what you are working with, we can start there.
Our pricing promise: We give you an exact written quote after the on-site inspection. You approve it before we start. No hidden fees, no surprise charges after the job. If scope changes during repair, we tell you before we proceed.
Answers to the questions Metro Atlanta property owners ask most often about engineered septic system design, costs, and timelines.
Georgia’s Georgia DPH On-Site Sewage Management program requires engineered design when daily flows exceed 2,000 gallons, when alternative system types are used (mound, ATU, LPP, drip), or when the site does not meet standard soil and separation criteria in DPH Rule 511-3-1. All engineered designs must be sealed by a Georgia-licensed Professional Engineer. The state also requires a certified soil classifier report for every new system – we coordinate that step as part of our engineering process. For a complete overview of permit types, fees, and timelines across all 9 counties, see our guide to septic system permits in Metro Atlanta.
Fulton County Environmental Health requires PE-sealed drawings for any alternative or non-standard system. Septic load evaluations in Fulton County are common for commercial properties and multi-family developments with higher daily flows. Fulton typically reviews engineered designs within 2-3 weeks of submission. Properties in Buckhead, Sandy Springs, and Alpharetta frequently need engineered designs due to steep terrain and proximity to the Chattahoochee River corridor. For step-by-step instructions on the Fulton County application process specifically, see our Fulton County septic permit guide.
Gwinnett County places strong emphasis on soil classification accuracy and setback compliance – expect thorough review of separation distances on your engineering drawings. Cobb County processes permits through the Cobb and Douglas Public Health office, which handles both conventional and engineered system approvals. DeKalb County’s older neighborhoods often trigger engineered designs because original lots were platted before current setback standards existed. We submit to all 9 Metro Atlanta counties regularly and know each office’s review preferences. After the engineering phase, our septic installation team handles the full build on the same contract.
Ready to book? We schedule fast to keep your timeline on track.
Licensed PEs and Certified Soil Classifiers
We know Metro Atlanta's soils, county codes, and failure patterns.
We submit engineered designs to Fulton, Gwinnett, Cobb, DeKalb, Forsyth, Rockdale, Douglas, Clayton, and Fayette counties. We know each county's review process and requirements.
If your property can use a conventional system, we will tell you - and save you the engineering fee. We run an inspection before recommending the design path so you only pay for what your site actually needs.
Every repair we perform is backed by our 1-year warranty.
Every engineered design starts with a site-specific problem. These are recent projects where standard systems were not an option.
The field lines in most Atlanta homes run 50-150 feet long. A standard 3-bedroom home on an average lot requires approximately 300-450 linear feet of drain field. Larger homes or homes on dense clay lots may need more.
We provide engineered septic system design across all 9 Metro Atlanta counties. Call 404-694-3060 to confirm we cover your property.
Sandy Springs · Buckhead · Alpharetta · Roswell · Fairburn · East Point
Lawrenceville · Lilburn · Snellville · Norcross · Duluth · Buford
Marietta · Smyrna · Kennesaw · Acworth · Powder Springs
Decatur · Stone Mountain · Tucker · Lithonia · Clarkston
Engineered system design is one part of a larger project. Most engineering clients also need septic installation in Metro Atlanta after the design phase, and properties replacing failed systems often start with a full septic inspection to document the existing system’s condition. If the issue is a failing drainfield rather than a full system replacement, our drainfield repair service may solve the problem without a full engineering redesign. For properties where the existing tank is sound but the field has failed, drainfield installation paired with an engineered replacement design is the most common path forward.
If you suspect your tank itself has structural issues – cracks, baffle failure, or inlet/outlet damage – our septic tank repair service can address the tank component while we handle the drainfield engineering separately. And once your engineered system is installed, regular septic tank pumping keeps the system running at the performance level the engineer designed it for.
Not sure which service you need? Call 404-694-3060 and describe the situation. We will point you to the right starting point.
Not sure if we cover your area? Call us now — we'll confirm in 30 seconds.
An engineered septic system is a custom-designed wastewater system created by a licensed Professional Engineer for properties where a standard gravity drainfield will not work. This includes properties with clay-heavy soil, high water tables, steep slopes, shallow bedrock, or lots too small for conventional trenches. Common engineered system types in Georgia include mound systems, aerobic treatment units, low-pressure pipe systems, and drip dispersal. The engineer designs the system to match your specific soil and site conditions, then produces PE-sealed drawings your county health department requires for permit approval.
Not always. Georgia DPH allows conventional gravity systems designed by a certified installer when the soil passes a standard perc test, the lot has adequate area, and daily flow stays under 2,000 gallons. You need a licensed engineer when the soil fails the perc test, the water table is too high, the site has steep slopes, daily flow exceeds 2,000 gallons, or the county requires an alternative system type. Most Metro Atlanta counties require PE-sealed drawings for any non-standard system. If your property is borderline, call 404-694-3060 and we can tell you which path makes sense.
Conventional septic systems can be designed by certified installers or designers. Engineered and alternative systems must be designed by a Georgia-licensed PE with on-site wastewater experience. The design process starts with a state-certified soil classifier testing the site. Septic Tank Guru works with licensed PEs and certified soil classifiers to handle the full process. If you are buying a property and want to confirm what the existing system needs, start with a pre-purchase septic inspection to understand the current system before committing to design work. A typical septic inspection takes 2-3 hours and gives you the full picture of tank condition, drainfield status, and whether engineering will be required.
Soil test review and site evaluation take 1-2 days. Custom system design with the PE takes 3-5 days. County-ready sealed drawings are delivered by day 7-10. County permit review adds 2-4 weeks depending on the county. Fulton and Gwinnett typically process permits faster than smaller counties. We handle the permit submission and health department coordination so you do not have to chase paperwork.
Poor soil and high water tables are exactly what engineered systems solve. Metro Atlanta’s heavy Piedmont clay often fails standard perc tests, but that does not mean you cannot build. A mound system raises the treatment zone above the water table. LPP systems distribute effluent evenly across marginal soils. Drip dispersal works on tight lots where trenches will not fit. We evaluate your soil report and design the system type your county will approve.
Engineering and design fees for residential engineered systems typically range from $1,500 to $3,000. Standard residential designs on acceptable soil run $800-$1,500. Complex or commercial designs may run $3,000-$7,500+. These fees cover soil test review, custom design by a licensed PE, and county-ready sealed drawings. Installation costs are separate and vary by system type. Call 404-694-3060 for a site-specific quote based on your soil report and property layout.
Engineered systems need more attention than conventional gravity systems. ATUs require quarterly inspections and annual service to keep the aerator and controls working. Mound systems and LPP systems have dosing pumps that need periodic checks. Drip systems require filter cleaning and flushing. All engineered systems still need regular septic tank pumping – typically every 3-5 years, though ATU systems may need more frequent attention. We provide maintenance plans for every engineered system we install.
A third-party soil survey and perc test in Metro Atlanta typically costs $400-$800, depending on the county and the soil classifier’s rates. This is not a Septic Tank Guru fee – the soil classifier is an independent, state-certified professional required by Georgia DPH. We coordinate the scheduling and review the results as part of our engineering process. For a full county-by-county cost breakdown, see our guide to perc test costs in Metro Atlanta.
Licensed PE-sealed drawings. County-ready in 7-10 days. Design and installation under one contractor. Serving all 9 Metro Atlanta counties.
Serving Atlanta, GA – Acworth – Vinings – Decatur – Stone Mountain – Lilburn – Douglasville – Fayetteville – Smyrna – Sandy Springs – Buckhead – and 20+ more cities.
