Cisterns

Capacity of Cisterns
For Each 10 inches in Depth

Twenty-five feet in diameter holds.. . . .3059 gallons
Twenty feet in diameter holds . . . . . . . .1958 gallons
Fifteen feet in diameter holds . . . . . . . . 1101 gallons
Fourteen feet in diameter holds . . . . . . .959 gallons
Thirteen feet in diameter holds . . . . . . . 827 gallons
Twelve feet in diameter holds . . . . . . . . 705 gallons
Eleven feet in diameter holds . . . . . . . . .592 gallons
Ten feet in diameter holds . . . . . . . . . . .489 gallons
Nine feet in diameter holds . . . . . . . . . . 396 gallons
Eight feet in diameter holds . . . . . . . . . . 313 gallons
Seven feet in diameter holds . . . . . . . . . .239 gallons
Six and one-half feet in diameter holds . . . .175 gallons
Five feet in diameter holds . . . . . . . . . . . . . .122 gallons
Four and one-half in diameter holds . . . . . . .99 gallons
Three feet in diameter holds . . . . . . . . . . . . .44 gallons
Two and one-half feet in diameter holds . . . 30 gallons
Two feet in diameter holds . . . . . . . . . . . . . .19 gallons
From page 37 of Houghtaling's Handbook

Growing up on Martha's Vineyard I never really thought much about cisterns. The Vineyard has plenty of underground water and my family and I drilled our own well. When I was researching Key West for a series of novels I set there, I discovered the small island had been on many pirates maps of the area. It was one of the few Islands (The Florida Keys) that actually had it's own fresh water supply. Here's the rub, once people decided to settle there, the underground spring could not support them all. When the Navy in 1823 came to the Island, they made huge cisterns to capture the rainwater.

Cisterns were used in the expansion of the West as well.

If you're a writer research your area see if they were used. Who knows you might be able to make use of this historical tidbit in your story. I did when my heroine from the North, fully garbed in a woolen dress, all the undergarments a proper woman would wear at that time, and Key West heat over took the poor gal. Naturally, she ended up in the cistern to cool down her body temp from the heat stroke she was suffering from. It was a fun scene to write and quite frankly there have been days in the hot Florida sun I would have loved to cool off in the cool waters of a cistern. Of course, you wouldn't want to drink that water but that's another story.