bdog,

Based on your estimated size, the volume of water in your pond will be 561,000 gallons. If you have good clay and use it to cover the pond bottom, then the pond should hold water without the need of a liner or bentonite.

Depending on where you live, your rainfall rates, and the amount of sunshine which drives evaporation rates, you may or may not need your household well to keep it full. In all probability, you will need the household well only in dry summer months of August and maybe July....and then only to keep it full. If you are willing to accept some fluctuation in water depths in summer, again depending on those other factors mentioned, you may not even need the household well.