Riverdale, GA rainwater: 42,864 gallons off a roof
Rainwater from a roof in Riverdale, GA
42,864gallons a year
That is a 1,500 sq ft asphalt roof under Riverdale, GA's normal 53.9 inches of rain, about 795 gallons for every inch that falls.
In Riverdale, 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 Riverdale 3.0 Wsw station (2.8 mi away). Riverdale, GA ranks 31st wettest of the 101 cities covered in Georgia.
Month by month in Riverdale
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 4.59 | 3,648 | |
| Feb | 5.18 | 4,117 | |
| Mar | 4.88 | 3,879 | |
| Apr | 4.37 | 3,473 | |
| May | 3.66 | 2,909 | 86 |
| Jun | 5.39 | 4,284 | |
| Jul | 4.88 | 3,879 | |
| Aug | 4.56 | 3,624 | |
| Sep | 3.69 | 2,933 | 82 |
| Oct | 3.46 | 2,750 | 111 |
| Nov | 4.26 | 3,386 | |
| Dec | 5.01 | 3,982 |
Jun is the wettest month (5.39 in, 4,284 gal off the roof); Oct the driest (3.46 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 Riverdale?
Best fit: one 55-gallon barrel, which delivers about 231 gallons to the garden in a normal year (82.7% of its need).
If you set one up, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Riverdale's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 231 | 41,433 |
| 110 gal | 231 | 41,433 |
| 165 gal | 231 | 41,433 |
| 275 gal | 231 | 41,433 |
| 550 gal | 231 | 41,433 |
| 1,000 gal | 231 | 41,433 |
| 1,500 gal | 231 | 41,433 |
| 2,500 gal | 231 | 41,433 |
| 5,000 gal | 231 | 41,433 |
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