Small Septic System Cost Guide

On February 16, 2025 By newsroom Topic: Home Services

A small septic system is ideal for properties with minimal wastewater needs, like a guest house, garage apartment, or a one-to-two-bedroom home. Here's a detailed breakdown of costs and considerations.

Average Cost Ranges

| System Component | Cost Range |
|--------------------------------|---------------------------|
| Small Septic Tank | $500–$1,500 |
| Complete System (500–1,000 gal) | $3,000–$18,600 |
| Leach Field Installation | $1,000–$5,000 |
| Excavation | $200–$1,800 |
| Perc Test | $750–$1,300 |
| Building Permits | $400–$2,000 |

Costs by Tank Size

| Tank Size (Gallons) | Household Size | System Cost (Installed) |
|--------------------------|--------------------|-----------------------------|
| 500 | 1 bedroom | $875–$1,150 |
| 750 | 1–2 bedrooms | $2,910–$13,900 |
| 1,000 | 2–4 bedrooms | $4,030–$18,600 |

Costs by Tank Material

| Material | 750-Gallon Cost | 1,000-Gallon Cost |
|---------------|---------------------|-----------------------|
| Concrete | $2,860–$13,900 | $3,830–$18,600 |
| Plastic | $2,660–$13,900 | $3,630–$18,600 |
| Fiberglass| $3,360–$13,900 | $4,330–$18,300 |

Costs by System Type

| System Type | Cost Range |
|----------------------------|------------------------|
| Anaerobic System | $3,000–$8,000 |
| Aerobic System | $10,000–$18,600 |

Anaerobic Systems: Most common and budget-friendly, using bacteria without oxygen to process waste.
Aerobic Systems: More expensive but highly efficient, using oxygen to break down waste.

Breakdown of Key Components

Septic Tank:
Size and type of material impact costs significantly.
500-gallon tanks: $500–$900; 1,000-gallon tanks: $900–$1,500.
Leach Field:
Filters wastewater naturally through soil, sand, and gravel.
Costs $1,000–$5,000, depending on soil composition and field size.
Excavation:
Required to bury the tank and piping.
Costs $200–$1,800, based on the land’s conditions.
Perc Test:
Assesses soil’s water absorption ability.
Costs $750–$1,300, necessary for code compliance.
Permits:
Required in most municipalities to meet regulations.
Fees range $400–$2,000.

Factors Influencing Cost

Tank Size: Larger tanks cost more but accommodate higher capacity.
Soil Composition: Rocky or clay-heavy soil increases excavation and leach field costs.
Labor Costs: Varies by region; urban areas often have higher rates.
Building Code Requirements: Stricter local codes may increase overall expenses.

DIY vs. Hiring a Professional

| DIY Installation | Professional Installation |
|---------------------------------|------------------------------------|
| Cost: Materials only ($500–$2,000). | Cost: $3,000–$18,600 (all-inclusive). |
| Risk: Fines for non-compliance, improper installation. | Benefit: Code-compliant and professionally insured work. |

Recommendation: Always hire a certified pro for septic system installations to ensure safety and legal compliance.

Ways to Save Money

Compare Quotes: Get estimates from multiple contractors.
Choose Anaerobic Systems: Opt for these if you don’t need high-efficiency processing.
Schedule Off-Season Installations: Prices may be lower when demand is less.
Maintain the System Regularly: Regular pumping ($290–$530) prevents costly repairs.

Septic System Lifespan

Concrete Tanks: Up to 40 years with proper care.
Plastic Tanks: Up to 50 years but vulnerable during installation.
Fiberglass Tanks: 20–30 years; strong but may shift in certain soils.

With regular maintenance and proper installation, your small septic system can serve your property reliably for decades.