How to Build Your Own Septic Tank

Building a home made sewage or septic tank is probably not the best idea that you can get. However, there are times when it may become necessary to manufacture your own sewage tank instead of buying one from the local dealer. Some reasons why you may need to build your own tank would be that the location makes it difficult to import a ready made tank, you may need an odd sized or extra large tank to handle your needs, or you may not be able to fit a standard shaped tank into the space that you have available. When the need to build your own tank arises, you should find that it is not a really tough task to accomplish.

Check local codes regarding septic tank capacity for the residence it will serve.

This will usually be in the form of how many gallons of water the tank will hold. You can compute the dimensions of the tank from this information. For example, if the tank needs to hold 1,000 gallons, you can construct a tank that has an interior space that is five feet wide by five feet high by 6 feet long. This will give you 150 cubic feet of storage. Since one cubic foot holds approximately 7.5 gallons of water, this will net you a tank that can hold roughly 1,125 gallons of water. Because you have a little air space at the top of the tank, this extra capacity will assure that you do not build a tank that is too small.

You will need to open up a hole large enough to accommodate the sewage tank.

This hole needs to be somewhat bigger than the dimensions of the tank that you plan to build. The reason for this is that you will require space to build forms for the foundation and room to work as you build the tank. It is best to allow at least three feet on each side of the perimeter of the sewage tank. The hole will need to be deep enough to allow the tank sit with all but the top foot of the tank’s walls to be below the level of your outgoing sewer line.

Drive stakes into the place where the corners of your new tank will be.

Make sure that these corners are square. It is just as important to build this sewage tank to exact precision as it is for your house. Since you plan to bury this tank and never see it again, you need it to be well-built so that it will last for as long as you need it. Fill the area where the bottom of the tank will rest with six inches of one inch rock. Cover this rock with plastic sheeting to form a moisture barrier.

Build forms around the perimeter of the tank’s foundation to hold the concrete.

Follow the local building codes for adding in the proper amount of steel rods to reinforce the concrete. Around the edges of the foundation, you will need upright steel rods to help secure the walls to the foundation when you pour them. Pour the foundation six inches thick with concrete and allow it to harden for 24 hours.

Use the same type of forms that are used for pouring basement walls to shape the walls of the sewage tank.

Make sure the forms are well braced. Insert the rest of the upright steel bars to reinforce the walls. Insert the elbows that will form your inlet and outlet ports through the forms before you pour the concrete. Pour the concrete to the desired height. Allow the concrete to cure inside the forms until they are sufficiently hardened to allow you to remove the forms.

Near the tank on a small piece of level ground, place a six inch bed of sand to use to form and pour the tank top.

Build the forms around the perimeter. Also build forms inside the top where you want to position your access hole to the septic tank. Fill the area between the forms with steel rods. If you plan to lift the lid with some type of crane or boom, insert steel loops into the corners of the lid to use for lifting it. Pour the lid to a thickness of four inches of concrete. After the concrete has hardened, remove the forms.

Coat the tops of the walls of the tank with tar or some type of sealant.

Move the lid over the tank until is rests in the correct position. Install any type of pump or stirring device that you may need to use with the septic tank. Make sure that the inlet and outlet pipes are still in proper position. Lengthen them to the length prescribed by the local codes. Have the tank inspected before covering it. Add risers over the access hole to bring it to ground level. Carefully refill around and over the tank after the septic lines have been attached to it.