How to calculate the optimal septic drain field size for ontario properties: a comprehensive guide
What To Know
- A septic drain field is an essential component of a septic system that receives treated wastewater from the septic tank and distributes it into the surrounding soil.
- The number of bedrooms in a dwelling determines the wastewater flow rate and the size of the drain field required.
- Calculating the septic drain field size in Ontario is a critical step in designing and installing a functional and compliant septic system.
Determining the appropriate septic drain field size in Ontario is crucial for ensuring the efficient and environmentally sound operation of your septic system. This blog post will guide you through the steps involved in calculating the drain field size, ensuring your system meets the requirements set by the Ontario Building Code.
Understanding the Role of a Drain Field
A septic drain field is an essential component of a septic system that receives treated wastewater from the septic tank and distributes it into the surrounding soil. The soil acts as a natural filter, removing harmful contaminants before the water seeps into the groundwater. The size of the drain field is determined by various factors, including the number of bedrooms in the dwelling, soil conditions, and local regulations.
Factors Affecting Drain Field Size
Several factors influence the size of a septic drain field, including:
- Number of Bedrooms: The number of bedrooms in a dwelling determines the wastewater flow rate and the size of the drain field required.
- Soil Conditions: The permeability of the soil is a critical factor. Highly permeable soils allow for faster infiltration, reducing the drain field size.
- Local Regulations: Municipalities in Ontario have specific regulations governing septic system design and installation. These regulations often include minimum drain field size requirements.
Ontario Building Code Requirements
The Ontario Building Code (OBC) sets minimum drain field size requirements based on soil permeability and the number of bedrooms. The following table provides a summary of these requirements:
| Soil Permeability | Bedrooms | Drain Field Area (m²) |
| — | — | — |
| High | 2 | 110 |
| High | 3 | 130 |
| High | 4 | 150 |
| High | 5+ | 170 |
| Medium | 2 | 130 |
| Medium | 3 | 150 |
| Medium | 4 | 170 |
| Medium | 5+ | 190 |
| Low | 2 | 150 |
| Low | 3 | 170 |
| Low | 4 | 190 |
| Low | 5+ | 210 |
Step-by-Step Calculation
1. Determine the Number of Bedrooms: Count the number of bedrooms in the dwelling.
2. Assess Soil Permeability: Conduct a soil permeability test to determine the rate at which water infiltrates into the soil. This test can be performed by a qualified professional.
3. Refer to OBC Requirements: Based on the number of bedrooms and soil permeability, refer to the OBC table to find the minimum required drain field area.
4. Adjust for Local Regulations: Check with your local municipality to determine if there are any additional regulations that may affect the drain field size.
Additional Considerations
- Slope: The drain field should be installed on land with a slope of less than 12%.
- Depth: The drain field should be installed at a depth of 60-90 cm.
- Spacing: Trenches within the drain field should be spaced at least 1.5 meters apart.
- Materials: The drain field should be constructed using approved materials, such as perforated pipes and gravel.
Importance of Accurate Calculations
Properly calculating the septic drain field size is essential for several reasons:
- Ensures System Efficiency: An undersized drain field can lead to wastewater backup and system failure.
- Protects the Environment: An oversized drain field can result in excessive water discharge, potentially contaminating groundwater and surface water.
- Complies with Regulations: Meeting the OBC requirements ensures that your septic system meets the minimum standards for health and environmental protection.
Wrapping Up
Calculating the septic drain field size in Ontario is a critical step in designing and installing a functional and compliant septic system. By following the steps outlined in this blog post and considering the factors discussed, you can ensure that your drain field meets the required standards and provides reliable wastewater treatment for your property.
FAQs
Q: What is the minimum drain field size for a 3-bedroom house in Ontario with high soil permeability?
A: 130 m²
Q: How often should I have my septic drain field inspected?
A: Every 3-5 years
Q: What are the signs of a failing septic drain field?
