Understanding Septic Tanks and Perc Tests for Home Building

Introduction

When building a home, especially in rural areas, understanding septic systems and percolation (perc) tests is crucial. These systems handle wastewater disposal where public sewers are unavailable. This guide walks you through the essentials of septic tanks and perc tests, helping you navigate this critical aspect of home building.

Key Takeaways

• Purchase land only if it passes a perc test and permit requirements.

• A failed perc test is not the end; alternative septic systems are available.

• Proper placement and design of septic systems are essential for functionality.

• Local installers and experts are invaluable resources.

Background on Septic Systems

A septic system consists of an underground pipe that channels wastewater from your home into a septic tank, typically located 10-15 feet from the house. The tank separates solids from the effluent, which then flows into a drain field. This system relies on gravity and natural bacterial processes.

Regulations and Professional Assistance

Septic system design, permitting, and installation are governed by local health or building departments. Engaging a local installer who understands these regulations can streamline the process.

Placement Considerations

Septic Tank

• Typically located 10-15 feet from the house.

• Positioned in an area free from landscaping or hardscaping.

• Accessible for regular maintenance.

Drain Field

The drain field location is complex and should meet the following criteria:

• Lower Elevation: Ideally, the drain field should be lower than the tank for gravity flow. If not, a pumped solution may be needed.

• Clear of Vegetation: Choose an already clear, level site to avoid future development conflicts.

• Optimal Soils and Drainage: Sandy soils are best; clay soils may require larger or alternative drain fields.

• Water Buffer: Maintain a buffer zone from potable water sources, typically 50-200 feet.

• Wetland Buffer: Avoid placing within buffer zones to surface water bodies.

• Ground Water Levels: Ensure sufficient vertical distance from groundwater to prevent contamination.

The Perc Test

A perc test assesses soil permeability to determine the suitability of a drain field. Land purchase offers should be contingent on a successful perc test. The process involves digging test holes, filling them with water, and measuring infiltration rates.

Cost

Perc tests generally cost between $750 and $1,750, with additional regulatory fees possible.

Failed Perc Test

If a conventional system fails, consider alternative septic systems depending on local regulations:

• Chamber System: Uses plastic chambers instead of gravel.

• Recirculating Sand Filter: Filters effluent through sand before reaching the drain field.

• Evapotranspiration: Effluent evaporates rather than infiltrates, suitable for dry climates.

• Aerobic Systems: Small-scale sewage treatment reducing effluent volume.

• Mound/Drip Systems: Engineered systems for challenging soil or bedrock conditions.

• Holding Tanks: Regularly pumped tanks as a last resort.

Conclusion

Understanding septic systems and perc tests is essential for rural home building. Proper planning, placement, and professional guidance ensure a functional and compliant wastewater disposal system. With this knowledge, you can confidently navigate the challenges and make informed decisions.