Rainwater calculator

[Donfini2]

Here’s how to figure out how much water you can collect from your roof.

https://water.usgs.gov/edu/activity-howmuchrain.html

 

[Donfini2]

Per state average

Avg. Total Yearly Precipitation (in.)
Alabama58.3
Alaska22.5
Arizona13.6
Arkansas50.6
California22.2
Colorado15.9
Connecticut50.3
Delaware45.7
Florida54.5
Georgia50.7
Hawaii63.7
Idaho18.9
Illinois39.2
Indiana
41.7
Iowa34
Kansas28.9
Kentucky48.9
Louisiana60.1
Maine42.2
Maryland44.5
Massachusetts47.7
Michigan32.8
Minnesota27.3
Mississippi59
Missouri42.2
Montana15.3
Nebraska
23.6
Nevada9.5
New Hampshire43.4
New Jersey47.1
New Mexico14.6
New York50.3
North Carolina17.8
North Dakota17.8
Ohio39.1
Oklahoma36.5
Oregon27.4
Pennsylvania42.9
Rhode Island
47.9
South Carolina49.8
South Dakota20.1
Tennessee54.2
Texas28.9
Utah12.2
Vermont42.7
Virginia44.3
Washington38.4
West Virginia45.2
Wisconsin32.6
Wyoming12.9

 

[Red dog]

Another quick method is find the square footage of the collection area, divide by 100 then multiply by 60. This will give you gallons per inch of rainfall.