How to Make a Septic Tank Drain Field
If you have a septic tank on your property, you will need a septic tank drain field, also known as a leach field or leach drain to complete the system and make it functional. While all septic tank drain fields require regular inspection, you can save a lot of money by digging one yourself.
Step 1 - Choose Your Site
You will want to choose a site that is away from the house, but close to the tank. The field should be at least 10 feet away from your edible garden and any water, such as a lake, river, or well.
Step 2 - Contact the Authorities
Verify if you need a permit to build the septic tank drain field or if you need to have the site inspected prior to starting work. Digging the field is a lot of hard work, but having to remove it and start over again is even worse. Verify all of the relevant laws and regulations prior to starting this project.
Step 3 - Make Sure the Soil is Appropriate
Even if it's not required, have the soil tested in the area. If the absorption capacity is too low, you will have trouble with back-ups. It's best to find this out before you dig.
Step 4 - Start Digging
You will need to dig either four 2-foot long trenches or two 50-foot trenches for a 1,000-gallon septic tank. Each trench should be 3-4 feet wide and equally deep.
Make your trenches so that they tilt downward slightly, but no more than a 1/4-inch incline for every 8 feet you have. You do not want the wastewater to pool at the bottom and rise up.
Step 5 - Place Gravel
Once the trenches are dug you will put at least 1-1 1/2 inches of gravel along the bottom of each trench. This allows for drainage under the pipe.
Step 6 - Add the Pipe
Place the pipe from the septic tank all along each trench. Use the clamps to hold the pipe in place at the septic tank drain so that it does not shift and misalign.
Step 7 - Add More Gravel
Once the entire pipe is in place, fill the trench with another 1-3 inches of gravel and let the gravel work its way down around the pipe.
Step 8 - Add the Cloth
When you have laid the pipe and gravel, drape your cloth over it. The cloth can be any type that breathes. Its function is to keep dirt and sand from blocking the drainage from the gravel.
Step 9 - More Dirt
When you are done with the pipe and gravel, your next step is to fill the rest of the trench in with dirt so that your field is level with the ground around it. You will need to wait two weeks for the ground to settle. When the ground settles, you will probably need to add more dirt to level your field.
Step 10 - Plantings (Optional)
There are several plants that will do well in the septic tank drainage field to keep it from looking like a complete eyesore. Keep in mind that you cannot aerate or till the soil. You also cannot add more than 2-3 inches of top soil. The plants you can use that require very little water and have shallow root systems include Japanese surge, carpet bugle, periwinkle, Irish moss, and some strains of wildflowers.
Many health departments require a percolation test to establish suitability of drainfield soil. Depending on your area, the law may call for a licensed professional or agency to perform this test for you. Research your local rules regarding septic tank usage.
In addition to the potential legality issues, if the septic tank drain field is installed incorrectly you will have a back-up problem in the tank.