When people refer to sewage treatment, they almost always refer to all of them as septic tanks. While this is usually incorrect, septic tank and field line systems are still the preferred method of sewage treatment in areas conducive for that type of treatment. For clarity, field lines refer to drain fields and leach fields since some people refer to them that way. Septic tank and field line sewer systems work best in areas of sandy soils and in this article we will describe the method of properly installing one.
Apply for a permit. In Grandpa's time, he and his brothers dug their own holes and trenches with shovels. I must say, some people knew what they were doing without government guidance, but most did not and inadvertently polluted the environment. To make sure it will be done correctly and legal, apply for your permit to install a septic tank and field line sewer system with your local health department.
Run a percolation test. The health department will guide you through the steps. A percolation test will indicate the porosity of the soil and how many feet of field lines will need to be installed. The actual tank size usually depends on the number of bedrooms and the percolation test has no bearing on it. Be sure to bring in legal documents showing ownership and property dimensions.
Get an approved tank and field line material. Believe it or not, sewage treatment is a highly regulated endeavor since so many people have screwed it up for so long. Make sure you purchase materials approved by the State. In many areas of the country, a homeowner can still install their own septic tank and field line system. If your hire a licensed installer, he would probably already be aware of approved materials.
Dig your holes and make sure you have your proper grades. It seems easy, but most people think that you just dig a hole for the tank and lay the field lines in trenches. Be sure your field lines are not sloped too much as this will cause premature failure. You will also need to have the proper grades for the pipes coming from the home. In Louisiana, the last 10' from the home to the septic tank cannot exceed ¼" per foot and prior to that they must be not be less than 1/8" per foot. The grades are very important so be sure to follow the guidelines. You also do not want to install the field lines too deep underground as they will not work correctly. A depth of 18"-30" is usually required.
Decide on the type of field line material. Conventional field lines, which is perforated pipe with gravel on top and bottom was once the only type of field lines you could install. These days there are new materials which require no gravel, and actually allow for a reduction in the amount of field lines.
Cover everything up and fill the septic tank with water. Be sure to cover your field lines with slightly mounded dirt over the field lines. You do not want all the water in your yard draining into your field lines. Fill the septic tank with a hose to prevent it from popping up in the event a downpour occurs before you can fill it with normal household usage.