Septic tanks are large underground tanks that are usually installed in rural areas where there is no underground sewer system, as a means to treat sewage and household waste. Solid matter sinks to the bottom of the tank and liquid waste flows off to a designated area where it's absorbed into the soil [source: Hygnstrom, Skipton, Woldt]. Septic tanks should be pumped out from time to time. How often this is necessary depends on how many people are using the septic tank on a regular basis [source: Bounds]. Building a septic tank from start to finish is not a job for an amateur. Indeed some states require septic tanks to be installed by a certified installer [source: Hygnstrom, Skipton, Woldt]. We will now learn something about a septic tank and what you can do in its construction.
- Determine the capacity The size of a septic tank depends on the number of people in the house. You will have to consult with your installer to determine what size tank you need.
- Decide what type of tank to buy Septic tanks can be made of steel, fiberglass, or reinforced concrete. Discuss these options with your installer and decide what's best for you.
- Determine the location Your septic tank should be located somewhat downhill from the house. This will allow you to take advantage of gravity between the house and the tank, by having the waste flow down the pipe into the tank.
- Excavate You can dig the hole to put your tank in yourself. Calculate the dimensions and the exact position of the hole you will need to dig by consulting with your installer or with a structural engineer. You will also need to excavate an area for a pipe of at least 4 inches (10 centimeters) in diameter, running from the house to the tank, so that for every 12 inches (30.5 centimeters) of pipe length there is a drop of ¼ inch (.64 centimeters). You will also need to run a pipe from the tank to the leach area, where the liquid waste seeps into the soil [source: Bounds, Hygnstrom, Skipton, Woldt].