Gahanna, OH rainwater: 34,948 gallons off a roof
Rainwater from a roof in Gahanna, OH
34,948gallons a year
That is a 1,500 sq ft asphalt roof under Gahanna, OH's normal 44.0 inches of rain, about 795 gallons for every inch that falls.
In Gahanna, OH 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 Columbus-Hap Cremean Wp station (1.8 mi away). Gahanna, OH ranks 35th wettest of the 176 cities covered in Ohio.
Month by month in Gahanna
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 3.14 | 2,496 | |
| Feb | 2.38 | 1,892 | |
| Mar | 3.45 | 2,742 | |
| Apr | 4.08 | 3,243 | 34 |
| May | 4.42 | 3,513 | |
| Jun | 4.74 | 3,767 | |
| Jul | 4.89 | 3,887 | |
| Aug | 4.02 | 3,195 | 41 |
| Sep | 3.51 | 2,790 | 105 |
| Oct | 3.16 | 2,512 | 148 |
| Nov | 2.97 | 2,361 | |
| Dec | 3.21 | 2,551 |
Jul is the wettest month (4.89 in, 3,887 gal off the roof); Feb the driest (2.38 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 Gahanna?
Best fit: one 55-gallon barrel, which delivers about 260 gallons to the garden in a normal year (79.3% 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 Gahanna's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 260 | 33,397 |
| 110 gal | 260 | 33,397 |
| 165 gal | 260 | 33,397 |
| 275 gal | 260 | 33,397 |
| 550 gal | 260 | 33,397 |
| 1,000 gal | 260 | 33,397 |
| 1,500 gal | 260 | 33,397 |
| 2,500 gal | 260 | 33,397 |
| 5,000 gal | 260 | 33,397 |
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 Ohio?
Legal. Ohio regulates rainwater cisterns used as a drinking-water source as private water systems (OAC chapter 3701-28): local health department permit, continuous disinfection and filtration. No state rule restricting non-potable collection or storage size.
Checked against the current source on 2026-11-06. Source