How to Construct the Concrete Base of a Garden Pond

Stake off the area where the pond will be installed by driving stakes in around the perimeter and trying them off with string.

Excavate the ground inside the marked off area, going about 6 inches deeper than the depth of the pond. For a project this size, you'll probably want to rent an excavator rather than dig this by hand.

Dig a trench all the way around the perimeter of the hole that's about 4 inches deep and 8 inches across.

Mix up a batch of concrete, following the directions on the package. Pour the concrete into the trench until it's full, then allow it to cure (usually about 4 days).

Level out the soil inside the hole and tamp it down so that it's even with the top of the concrete foundation inside the trench.

Mix up another batch of concrete, and spread it out over the entire surface of the pond hole (including the previously poured concrete foundation) so that it's now 3 inches thick. Allow it about 4 days to cure.

Place galvanized mesh rebar on top of the concrete, then add another 3-inch layer of concrete. Allow the concrete to cure.

Mix up another batch of concrete, this time with reinforcing fibers in it, and spread a half-inch layer over the previously poured concrete. The reinforcing fibers will help prevent the base from cracking and leaking. Allow the concrete to dry.

Install concrete block walls around the perimeter of the pond, going high enough that you can add a layer or two of bricks on top of the concrete blocks so that they'll be level with the surrounding ground. Stagger each row of blocks to increase the strength of the wall.

Pour concrete into the holes inside the blocks, as well as in the spaces between the blocks. Allow the concrete to cure, then add the layer of bricks on top of the concrete, cementing them in place. Allow at least 48 hours for the concrete to set.

Dampen the walls slightly, then cover them with a half-inch layer of concrete that contains the reinforcing fibers. Allow it to dry.

Add a layer of finishing bricks or stone on top of the walls, using mortar to keep them in place.

Paint the inside of the pond with a waterproof sealant.