How to Build an Underground Cistern

An underground cistern is a structure that allows water to flow away from a building's foundation and your home. Cisterns have been around since ancient times, and underground cisterns have been a part of many cultures and societies. Building an underground cistern for your home is an easy project that can be accomplished by any level of do-it-yourselfer. Building an underground cistern involves digging a trench, filling it with concrete and tile, and allowing it to set up.

To build an underground cistern for your home, you need to acquire some materials and tools and follow these steps explained in this how-to article.

Step 1 - Dig a Trench

To build an underground cistern for your yard, you will need to dig a trench. The trench will need to be graded so that water flows downward away from the home's foundation. It is best to rent a trench digger, but you can also dig the trench needed for your underground cistern by hand with shovels. The trench digger will allow you to save time and be more efficient in constructing your underground cistern.

Use a level to determine the rise and run relative to your trench's slope to grade the trench. As you remove dirt from the yard, check the grading periodically to ensure that you do not remove too much dirt.

Step 2 - Pour Concrete in the Trench

Once you have removed the dirt to form the trench and have leveled the ground out, you need to pour concrete into the trench. Use a cement mixer to mix the concrete to pour it into the trench. Follow the instructions on the bag for the concrete to make sure that you properly mix the concrete.

Lay 2x4 wood inside the trench at equal distances to form breaks for the concrete. As the concrete cures and hardens, it will need a place to expand and contract. If you do not create the gaps in the concrete as it is being poured, the base of the cistern will crack, and you will need to rip the concrete out and start over.

Step 3 - Create the Terra Cotta Walls

After the concrete has been poured into the trench, allow some time for it to dry before proceeding with your build. You should lay concrete into the sides of the trench after the base has completely cured to set the terra cotta tile for your underground cistern. Complete one side of the cistern and wait for it to set up to make sure that the tiles are correctly placed before working on the opposing side of the cistern.

Step 4 - Complete the Cistern

With the tile walls set in place, allow the concrete on the opposing wall to cure. Once dried, your underground cistern should be complete and ready to move water away from the house.