What is a Percolation Test? Why is it Important for Septic Systems?
If you are buying a property or installing a septic system, you need to know the concept of the percolation test. The percolation test is a litmus test for determining the suitability of the land for your septic system. This blog will familiarize you with the perc test and why it is important.
What is a Percolation Test?
A percolation test measures the amount of water that the soil in a specific area can absorb. This information is essential for constructing septic systems and other drainage infrastructures. The drainage system relies on the soil to absorb and filter water for treating waste. If the soil can’t absorb water and allows it to flow through it, the drainage system can overload and be damaged. Drainage system damage can lead to environmental hazards and expensive repairs.
Understanding Percolation Tests
Perc tests are a reflection of the condition of the drainage system. Wastewater flows into the septic tank, where the solids settle at the bottom and the scums float. The remaining liquid then flows through the drain pipes and is filtered by the soil. A percolation test determines the soil's ability to filter the effluent liquid. Perc rates differ depending on soil type, density, and groundwater levels. A good perc rate signifies that the water is treated effectively and does not contaminate the ground or surface water.
Step-by-Step Guide to Conducting a Perc Test
Digging the Hole: Dig several holes with the size of the drain system and the pipes. This size enables better testing. Ensure the sides are smooth and straight.
Pre-Soaking: Fill the holes with water and let them soak for the whole day to saturate the soil. This would ensure more accurate test results.
Measuring the Drop: After the pre-soaking stage, fill the soil with water up to a specific level. Measure the drop in the water level at regular intervals, most preferably at 30 minutes.
Calculating the Percolation Rate: The percolation rate is calculated by dividing the time interval by the drop in water level. This calculation determines the time soil to absorb water by inch. The standard unit of measurement for a percolation rate is minutes per inch.
Repeat: Repeat the process several times to collect more data. Use this data to calculate the average percolation rate of the area. The more data you have, the better and more accurate the test results will be.
Interpreting Perc Test Results
Too Slow (e.g., > 5 minutes/inch):
Indication of a poor quality drainage system
Likely to have high clay content
Not suitable for building a drainage system
A percolation rate below 5 minutes per inch is considered to be too slow. A slow percolation rate indicates a poor drainage system. This means the soil has high clay content and thus does not allow the water to flow through easily and filter. This can lead to effluent pooling and cause wastewater to pollute surface and groundwater. Water contamination will cause health hazards and unsanitary conditions for living. Suitable modifications are needed to make such areas appropriate for a drainage system, such as a mound system.
Ideal (e.g., 5 minutes/inch):
Adequate drainage system
Suitable for a typical septic system
The ideal percolation rate for the soil is between 5 and 15 minutes. The rate indicates that the soil is suitable for building a proper drainage system. A rate within this range indicates that the soil will filter wastewater adequately to prevent environmental contamination. The ideal range can vary from location to location.
Too Fast (e.g., < 15 minutes/inch):
Indicates fast drain
Does not adequately drain the wastewater
High likelihood of contamination
If the percolation rate is over 15 minutes, it means the soil is draining the water too fast. So, it won’t filter the wastewater before it reaches groundwater, causing contamination. It will pose environmental risks and a drinking water crisis. You may have enhanced filters to purify the wastewater.
Conclusion
Understanding the percolation rate and how to conduct a test is the key to installing a septic system. While some DIY methods can help you understand the basic capabilities of a perc rate of soil, perc tests should be done by professionals. Conducting a perc test can determine whether a home needs modification or not, and save people money on expensive repairs and environmental hazards.
FAQs
How long does a perc test remain valid?
A perc test remains valid for 2 to 5 years before it is conducted again.
Can I conduct a perc test myself?
It is recommended that you hire a professional septic system expert to handle the testing
