Atlanta, GA rainwater: 41,171 gallons off a roof
How much rain a roof in Atlanta, GA collects
41,171gallons a year
That is a 1,500 sq ft asphalt roof under Atlanta, GA's normal 51.8 inches of rain, about 795 gallons for every inch that falls.
In Atlanta, 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 Atlanta 2.3 Ne station (2.3 mi away). Atlanta, GA ranks 61st wettest of the 101 cities covered in Georgia.
Month by month in Atlanta
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 4.68 | 3,720 | |
| Feb | 4.25 | 3,378 | |
| Mar | 4.80 | 3,815 | |
| Apr | 4.02 | 3,195 | 41 |
| May | 4.23 | 3,362 | 15 |
| Jun | 4.55 | 3,616 | |
| Jul | 5.06 | 4,022 | |
| Aug | 4.48 | 3,561 | |
| Sep | 3.92 | 3,116 | 54 |
| Oct | 3.51 | 2,790 | 105 |
| Nov | 4.09 | 3,251 | |
| Dec | 4.21 | 3,346 |
Jul is the wettest month (5.06 in, 4,022 gal off the roof); Oct the driest (3.51 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
Which tank size is worth it in Atlanta
Best fit: one 55-gallon barrel, which delivers about 180 gallons to the garden in a normal year (83.9% 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 Atlanta's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 180 | 39,866 |
| 110 gal | 180 | 39,866 |
| 165 gal | 180 | 39,866 |
| 275 gal | 180 | 39,866 |
| 550 gal | 180 | 39,866 |
| 1,000 gal | 180 | 39,866 |
| 1,500 gal | 180 | 39,866 |
| 2,500 gal | 180 | 39,866 |
| 5,000 gal | 180 | 39,866 |
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