Griffin, GA rainwater: 43,070 gallons off a roof
Rainwater from a roof in Griffin, GA
43,070gallons a year
That is a 1,500 sq ft asphalt roof under Griffin, GA's normal 54.2 inches of rain, about 795 gallons for every inch that falls.
In Griffin, GA a single barrel does most of the work. Storms come often enough that a small tank refills before it runs dry, and a bigger one would mostly sit full.
Rainfall: NOAA 1991-2020 climate normals, the Experiment station (1.5 mi away). Griffin, GA ranks 27th wettest of the 101 cities covered in Georgia.
Month by month in Griffin
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 5.27 | 4,189 | |
| Feb | 4.32 | 3,434 | |
| Mar | 5.08 | 4,038 | |
| Apr | 4.04 | 3,211 | 39 |
| May | 3.71 | 2,949 | 80 |
| Jun | 4.91 | 3,902 | |
| Jul | 5.07 | 4,030 | |
| Aug | 5.08 | 4,038 | |
| Sep | 4.39 | 3,489 | |
| Oct | 3.31 | 2,631 | 130 |
| Nov | 4.01 | 3,187 | |
| Dec | 5.00 | 3,974 |
Jan is the wettest month (5.27 in, 4,189 gal off the roof); Oct the driest (3.31 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
Barrel or cistern in Griffin?
Best fit: one 55-gallon barrel, which delivers about 204 gallons to the garden in a normal year (82.2% of its need).
Before you buy, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Griffin's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 204 | 41,651 |
| 110 gal | 204 | 41,651 |
| 165 gal | 204 | 41,651 |
| 275 gal | 204 | 41,651 |
| 550 gal | 204 | 41,651 |
| 1,000 gal | 204 | 41,651 |
| 1,500 gal | 204 | 41,651 |
| 2,500 gal | 204 | 41,651 |
| 5,000 gal | 204 | 41,651 |
Simulated storm by storm through a normal year using the station's count of days with 0.1 in or more of rain each month.
Is rainwater collection legal in Georgia?
Legal. Outdoor irrigation use is unrestricted; indoor non-potable systems must follow Appendix I 'Rainwater Recycling Systems' of the Georgia amendments to the state plumbing code. No state storage cap; potable use depends on local rules.
Checked against the current source on 2026-11-06. Source