How to Dig your Pond Deep Enough

The depth of your pond is critical to fish and plant health. If you have a shallow pond, your water lilies and fish will get too hot. If your pond is too shallow in colder climates, it can freeze solid and kill all occupants. Digging the sides straight down rather than with shelves for plants makes less surface for the sun to hit and therefore cuts down on algae growth.

Digging your pond

  1. Call or contact your local extension service to find the freeze line. Dig your pond deeper than your freeze line or it will freeze solid in the winter
  2. After you have marked the boundaries of your pond, start digging. Start digging in the middle and throw the soil out of the pond about 2 feet past the edge of your pond.
  3. Dig the edges last. Do not step on the edges because if they break, you will need to make them strong with roofing flashing or some other sturdy material that will hold the wall up so it does not collapse under the weight of the rocks that will go there as you complete building your pond.
  4. Measure and make sure you are deeper than your freeze line by at least a foot. Your fish will stay there in the winter, in torpor, and live through the winter with no problem. You must keep a hole open in the ice so gases can be exchanged. Your fish, even though almost in suspended animation, still need to breathe.
  5. When you reach the necessary depth, flatten the bottom, remove all sticks, shells, roots or other sharp objects from the bottom so it is as smooth as you can get it.

Things You Will Need

  • A shovel
  • • A tape measure
  • • What your freeze line is where you live.


  • If you live where it does not freeze or rarely freezes, dig your pond 18" deep. If you have koi, dig your pond at least 2 1/2' to 3' deep if you can. If you hit water, stop there.
  • Digging a sump at one end of your pond will make it easier to clean when the time comes. You can sweep all the debris into the sump and vacuum it out easily.


  • Do not dig your pond so the sides slope like a bowl. You will slip and fall in each time you try to step in the pond.


About the Author

This writer has been at the writing craft for over 50 years from long before computers or even electric typewriters. Now retired from her day job she spends retirement hours writing for online sites.