Lilburn, GA rainwater: 42,546 gallons off a roof
Rainwater from a roof in Lilburn, GA
42,546gallons a year
That is a 1,500 sq ft asphalt roof under Lilburn, GA's normal 53.5 inches of rain, about 795 gallons for every inch that falls.
In Lilburn, 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 Lawrenceville 4.2 Sw station (5.9 mi away). Lilburn, GA ranks 38th wettest of the 101 cities covered in Georgia.
Month by month in Lilburn
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 4.83 | 3,839 | |
| Feb | 4.66 | 3,704 | |
| Mar | 4.91 | 3,902 | |
| Apr | 3.96 | 3,147 | 49 |
| May | 3.90 | 3,100 | 56 |
| Jun | 4.70 | 3,736 | |
| Jul | 4.63 | 3,680 | |
| Aug | 5.05 | 4,014 | |
| Sep | 4.37 | 3,473 | |
| Oct | 3.54 | 2,814 | 101 |
| Nov | 4.13 | 3,283 | |
| Dec | 4.85 | 3,855 |
Aug is the wettest month (5.05 in, 4,014 gal off the roof); Oct the driest (3.54 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
What size rain barrel for Lilburn
Best fit: one 55-gallon barrel, which delivers about 170 gallons to the garden in a normal year (82.6% of its need).
If you buy one, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Lilburn's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 170 | 41,146 |
| 110 gal | 170 | 41,146 |
| 165 gal | 170 | 41,146 |
| 275 gal | 170 | 41,146 |
| 550 gal | 170 | 41,146 |
| 1,000 gal | 170 | 41,146 |
| 1,500 gal | 170 | 41,146 |
| 2,500 gal | 170 | 41,146 |
| 5,000 gal | 170 | 41,146 |
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