Most homeowners pay $3,500–$12,500 to install a new septic tank and leach field together. Conventional gravity systems sit at the low end, while mound and other engineered fields push the total to $20,000 or more (Angi, HomeGuide and Bob Vila data, as of October 2026).
Updated October 8, 2026. Source: Angi + 4 more. National US estimates.
The leach field (also called a drain field) is where wastewater from the tank soaks into the soil and gets treated. It is usually the largest and most variable part of a septic job, because its size and design depend on your soil and household size.
This guide covers combined tank-and-field prices, costs by field type and what happens when a failed field has to be replaced. For tank-only prices and system types, see our septic tank installation cost guide.
Average cost
Installed prices for a new septic tank plus leach field, national averages as of October 2026:
| Scenario | Typical range | Notes |
|---|---|---|
| Conventional tank and gravel or chamber field | $3,500–$8,500 | Good soil, 3-bedroom home |
| Tank plus aerobic or evapotranspiration field | $10,000–$18,000 | Extra treatment or dry climates |
| Tank plus mound or engineered field | $10,000–$20,000+ | Shallow soil, high water table or poor perc |
Leach field cost by type
| Field type | Installed cost | Angi average |
|---|---|---|
| Conventional (anaerobic) | $2,000–$6,000 | About $5,000 |
| Aerobic | $7,000–$10,000 | About $7,000 |
| Evapotranspiration | $8,000–$15,000 | About $8,000 |
| Mound | $10,000–$20,000 | About $12,000 |
Unit prices for tank and field work
| Item | Typical cost |
|---|---|
| Leach lines | $20–$45 per linear foot |
| New septic line from house to tank | $40–$180 per linear foot |
| Excavating an old field | $1–$5 per sq. ft. |
| Perc test | $600–$2,000 |
| Sod after installation | $1–$2 per sq. ft. |
Cost breakdown: materials, labor, permits and extras
Line-item estimate for installing a 1,000-gallon tank and a conventional gravity leach field for a 3-bedroom home. Ranges are national, as of October 8, 2026.
| Cost item | Typical range | What it covers |
|---|---|---|
| Septic tank (1,000 gallons) | $1,000–$1,500 | Concrete or plastic tank, delivered |
| Leach field (pipe, gravel or chambers, D-box, labor) | $1,000–$2,500 | Conventional field sized to the perc results |
| Tank installation labor & excavation | $700–$2,000 | Setting the tank, house line, backfill |
| Perc test | $250–$1,000 | Required before design approval |
| Permits & inspections | $300–$1,000 | Most counties require at least two inspections |
| Contingency (about 10%) | $250–$500 | Rock, roots, extra fill or regrading |
| Estimated total | $3,500–$8,500 | Before any discounts or rebates |
Labor is often around 60% of a tank-and-field project, so site conditions matter more than the parts.
What affects the price
- Field size, which depends on household size and soil. Fields are sized from household size (usually bedrooms) and the soil's absorption rate. Leach lines cost about $20–$45 per linear foot, so a larger home or slower soil means a longer, pricier field.
- Soil percolation results. A perc test costs about $600–$2,000. Fast, even absorption allows a compact conventional field; slow or saturated soil may require a mound or engineered design.
- System design (gravity, pressure distribution, mound). Gravity fields are the cheapest, at about $2,000–$6,000 for the field. Pressure-dosed and drip designs need pumps and controls, and mound fields run about $10,000–$20,000.
- Permits and engineering. Drain field permits run about $450–$2,000, engineers bill around $125–$200 per hour for designs, and each required inspection can cost $200–$900.
- Excavation and access. Excavation costs about $1–$5 per sq. ft.; rock, slopes, trees and tight access raise the price. Tree or root removal can add $200–$2,000, and regrading $1,000–$3,300.
- Replacement of an existing failed field. Replacing a failed field adds removal or abandonment of the old one: excavating it costs $1–$5 per sq. ft. and an abandonment permit $100–$250. HomeGuide puts a full field replacement at $3,000–$15,000, about $7,900 on average.
Ways to save
- Order the perc test early. Knowing the soil's limits before you design the house or buy the lot can save thousands on the system.
- If only the field has failed, ask whether rejuvenation or repair ($1,000–$5,000) is possible before replacing it, and whether the existing tank can be reused.
- Collect at least three bids based on the same approved design, and confirm that permits, inspections, backfill and seeding are included.
- Keep the field close to the house and accessible, and avoid sites that need major clearing or regrading.
- Protect the new field: pump the tank every 3–5 years and keep cars, structures and trees off the field. See our septic tank pumping cost guide for maintenance prices.
How to get an accurate quote
Get written quotes from at least three licensed septic installers. Provide each one with:
- The perc test or soil evaluation and, if available, the approved system design.
- The number of bedrooms and any plans to add bedrooms later.
- A site plan showing the house, well, slopes, property lines and access for excavators.
- Whether an existing tank or field must be pumped, abandoned or removed, and ask what permits, inspections and restoration are included.
FAQ
How long does a leach field last?
A well-maintained field can last decades, and the EPA notes that fields older than 25–30 years may need attention. Skipping pumping lets solids clog the field and shortens its life.
Can I replace only the leach field and keep the tank?
Often yes, if an inspection shows the tank is sound. Angi reports drain field replacement alone averages about $7,000, versus $3,500–$8,500 for tank and field together.
How big does a leach field need to be?
It depends on household size and perc results, and your county sets the sizing rules. The designer or installer will size it from the soil evaluation.
For the big picture, start with our complete septic tank installation cost guide.
Related cost guides
Sources
- Angi — How Much Does It Cost to Replace a Septic Tank and Drain Field? [2026 Data] (updated Jul 8, 2026). Checked October 8, 2026.
- HomeGuide — How Much Does a Leach or Drain Field Replacement Cost? (2026) (Dec 22, 2025). Checked October 8, 2026.
- HomeGuide — How Much Does a Septic Tank System Cost? (2026) (Sep 22, 2025). Checked October 8, 2026.
- Bob Vila — How Much Does It Cost to Replace a Septic Tank and Drain Field? (updated Dec 12, 2023). Checked October 8, 2026.
- US EPA — Why Maintain Your Septic System (accessed Oct 2026). Checked October 8, 2026.
Prices are estimates and vary by location and provider. See our methodology and editorial policy. Browse all foundation & water cost guides.