Forest Park, GA rainwater: 40,082 gallons off a roof
How much rain a roof in Forest Park, GA collects
40,082gallons a year
That is a 1,500 sq ft asphalt roof under Forest Park, GA's normal 50.4 inches of rain, about 795 gallons for every inch that falls.
In Forest Park, 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 Hartsfield Intl Ap station (4.8 mi away). Forest Park, GA ranks 80th wettest of the 101 cities covered in Georgia.
Month by month in Forest Park
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 4.59 | 3,648 | |
| Feb | 4.55 | 3,616 | |
| Mar | 4.68 | 3,720 | |
| Apr | 3.81 | 3,028 | 67 |
| May | 3.56 | 2,830 | 98 |
| Jun | 4.54 | 3,608 | |
| Jul | 4.75 | 3,775 | |
| Aug | 4.30 | 3,418 | 6 |
| Sep | 3.82 | 3,036 | 66 |
| Oct | 3.28 | 2,607 | 133 |
| Nov | 3.98 | 3,163 | |
| Dec | 4.57 | 3,632 |
Jul is the wettest month (4.75 in, 3,775 gal off the roof); Oct the driest (3.28 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 Forest Park?
Best fit: one 55-gallon barrel, which delivers about 309 gallons to the garden in a normal year (83.2% 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 Forest Park's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 309 | 38,603 |
| 110 gal | 309 | 38,603 |
| 165 gal | 309 | 38,603 |
| 275 gal | 309 | 38,603 |
| 550 gal | 309 | 38,603 |
| 1,000 gal | 309 | 38,603 |
| 1,500 gal | 309 | 38,603 |
| 2,500 gal | 309 | 38,603 |
| 5,000 gal | 309 | 38,603 |
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