This may be a dumb question, so I will apologize early.

When determining the amount of available water in a well, what diameter do you use for the well? Example:

I have a 260 foot deep well, pump set at 255 feet. According to the well guy's write up, static water level is at 168 feet. It is a 6" drilled well, with 250 feet of 4 inch casing.

Now, I understand that I have 87 feet of standing water in the well, but do I base the rest of my calculations off of the 4" casing diameter, or the 6" drilled well size?