Cumming, GA rainwater: 44,803 gallons off a roof
Rainwater from a roof in Cumming, GA
44,803gallons a year
That is a 1,500 sq ft asphalt roof under Cumming, GA's normal 56.4 inches of rain, about 795 gallons for every inch that falls.
In Cumming, 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 Cumming 2n station (1.6 mi away). Cumming, GA ranks 7th wettest of the 101 cities covered in Georgia.
Month by month in Cumming
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 5.39 | 4,284 | |
| Feb | 5.15 | 4,093 | |
| Mar | 5.16 | 4,101 | |
| Apr | 4.32 | 3,434 | 4 |
| May | 4.23 | 3,362 | 15 |
| Jun | 4.69 | 3,728 | |
| Jul | 4.89 | 3,887 | |
| Aug | 4.92 | 3,910 | |
| Sep | 4.03 | 3,203 | 40 |
| Oct | 3.97 | 3,155 | 47 |
| Nov | 4.42 | 3,513 | |
| Dec | 5.20 | 4,133 |
Jan is the wettest month (5.39 in, 4,284 gal off the roof); Oct the driest (3.97 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 Cumming?
Best fit: one 55-gallon barrel, which delivers about 87 gallons to the garden in a normal year (82.1% 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 Cumming's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 87 | 43,426 |
| 110 gal | 87 | 43,426 |
| 165 gal | 87 | 43,426 |
| 275 gal | 87 | 43,426 |
| 550 gal | 87 | 43,426 |
| 1,000 gal | 87 | 43,426 |
| 1,500 gal | 87 | 43,426 |
| 2,500 gal | 87 | 43,426 |
| 5,000 gal | 87 | 43,426 |
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