Septic Tank Installation Cost Calculator
* Includes tank, installation labor, and drain field. Final costs vary by soil conditions, site access, and local regulations.
Disclaimer: Estimates are for budgeting purposes only. Actual costs vary by location, contractor, material availability, and project complexity. Always get professional quotes for exact pricing.
Septic System Cost by Type
| System Type | System Cost | With Drain Field (100 lf) |
|---|---|---|
| Conventional | $3,500 – $8,500 | $4,500 – $11,500 |
| Chamber | $4,000 – $9,000 | $5,000 – $12,000 |
| Aerobic | $10,000 – $20,000 | $11,000 – $23,000 |
| Mound | $10,000 – $25,000 | $11,000 – $28,000 |
* Costs include tank, installation, and drain field. Add $200–$500 for perc test and $200–$1,000 for permits.
How We Calculate
Our septic tank installation cost calculator estimates total project costs based on system type, tank size, and drain field length. Pricing includes the septic tank, professional installation, and drain field construction.
How the math works: System cost = base cost for system type + tank size upcharge. Drain field = length x $10–$30 per linear foot. Add-ons: perc test ($200–$500) and permit ($200–$1,000). Total = system + drain field + add-ons.
System Types
Conventional ($3,500–$8,500): Gravity-fed system with septic tank and gravel drain field. Most common and affordable option. Works well with adequate soil drainage (passing perc test). Tank separates solids from liquid, effluent flows to drain field for soil treatment. Requires 1% slope for gravity flow.
Chamber ($4,000–$9,000): Uses plastic leaching chambers instead of gravel in the drain field. Easier installation, no gravel hauling required. Better performance in areas with variable drainage. Chambers provide more storage capacity during peak usage. 30% lighter to install than gravel systems.
Aerobic ($10,000–$20,000): Uses oxygen injection to accelerate bacterial decomposition. Produces cleaner effluent (suitable for surface discharge in some areas). Required when soil drainage is poor or lot size is small. Needs electricity and annual maintenance contract ($200–$400/year). More complex but more effective treatment.
Mound ($10,000–$25,000): Raised drain field built above grade for properties with high water tables, shallow bedrock, or poor soil. Sand mound constructed 2–4 feet above natural grade. Requires pump to lift effluent to mound. Most expensive option but solves difficult site conditions.
Tank Sizes
750 Gallon (base price): Suitable for 1–2 bedroom homes with low water usage. Minimum code requirement in many areas. Holds approximately 2 days of wastewater for a 2-person household.
1,000 Gallon (+$500–$800): Standard for 3-bedroom homes. Most common residential size. Recommended for families of 3–4 people. Provides adequate capacity for daily laundry, dishwasher, and shower use.
1,500 Gallon (+$1,000–$1,500): Required for 4+ bedroom homes or high water usage households. Provides buffer capacity for large families, frequent entertaining, or homes with hot tubs. Some counties require this size for homes over 3,500 sq ft.
Data Sources
Pricing from HomeAdvisor, Angi, and licensed septic installers. System requirements per EPA and state health department guidelines. We review and update costs regularly.
Last updated: 2026-02-11
Frequently Asked Questions
How much does it cost to install a septic tank? +
Septic tank installation costs $4,500–$25,000 depending on system type and tank size. A conventional system with a 750-gallon tank averages $3,500–$8,500 for the tank and installation. Add $1,000–$3,000 for the drain field (100 linear feet at $10–$30/lf). Perc test ($200–$500) and permits ($200–$1,000) are additional. Total average project for a 3-bedroom home runs $5,000–$13,000.
What are the different types of septic systems? +
The four main septic system types are conventional (gravity-fed, $3,500–$8,500), chamber ($4,000–$9,000, uses plastic chambers instead of gravel), aerobic ($10,000–$20,000, uses oxygen to treat waste for higher-quality effluent), and mound ($10,000–$25,000, raised drain field for high water tables or poor soil). Conventional systems work for most homes with adequate soil drainage. Aerobic and mound systems are required when soil percolation is poor or the water table is high.
What size septic tank do I need? +
Septic tank size depends on home bedrooms and water usage. A 750-gallon tank suits 1–2 bedroom homes. A 1,000-gallon tank handles 3 bedrooms (most common residential size). A 1,500-gallon tank is for 4+ bedrooms or high water usage. Larger tanks cost $500–$1,500 more than the base 750-gallon tank. Local codes specify minimum sizes — always check with your county health department before installation.
How long does a septic system last? +
A well-maintained septic system lasts 25–30 years. Concrete tanks last 40+ years while plastic and fiberglass tanks last 20–30 years. The drain field typically needs replacement after 20–30 years. Pump the tank every 3–5 years ($300–$500 per pump) to extend system life. Avoid flushing grease, chemicals, or non-biodegradable items. Signs of failure include slow drains, sewage odors, soggy drain field, and lush grass over the drain field.
What is a perc test and do I need one? +
A percolation (perc) test measures how quickly water drains through your soil. It costs $200–$500 and is required by most counties before septic system installation. The test involves digging holes in the proposed drain field area and measuring water absorption rates. Passing results (typically 1–60 minutes per inch) determine what type of septic system your property can support. Failing a perc test may require a mound or aerobic system instead of conventional.
How long does septic tank installation take? +
Septic tank installation takes 3–7 days for a conventional system. Day 1: site preparation and excavation. Days 2–3: tank placement and drain field trenching. Days 4–5: piping, connections, and backfill. Days 6–7: inspection and final grading. Aerobic and mound systems take 5–10 days due to additional complexity. Weather delays, rocky soil, or high water table can extend timelines. Most counties require a final inspection before use.
Can I install a septic system myself? +
DIY septic installation is not recommended and is illegal in many jurisdictions. Permits require licensed installer signatures. Improper installation risks groundwater contamination, system failure, and health hazards. Even if your county allows owner-installed systems, you still need permits ($200–$1,000), perc test ($200–$500), and inspections. Excavation alone requires heavy equipment rental ($500–$1,000/day). Hire a licensed septic contractor for reliable, code-compliant installation.
What are the ongoing costs of a septic system? +
Annual septic system maintenance costs $200–$500. Pump the tank every 3–5 years ($300–$500). Annual inspection costs $100–$200. Aerobic systems require annual maintenance contracts ($200–$400/year) for the air pump and chlorinator. Septic additives are $20–$40/year but not always necessary. Budget $3,000–$7,000 for drain field replacement if needed after 20–30 years. Proper maintenance prevents costly emergency repairs ($2,000–$10,000).
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