Franklin, OH rainwater: 33,628 gallons off a roof
How much rain a roof in Franklin, OH collects
33,628gallons a year
That is a 1,500 sq ft asphalt roof under Franklin, OH's normal 42.3 inches of rain, about 795 gallons for every inch that falls.
In Franklin, 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 Franklin station (1.2 mi away). Franklin, OH ranks 75th wettest of the 176 cities covered in Ohio.
Month by month in Franklin
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 3.32 | 2,639 | |
| Feb | 2.54 | 2,019 | |
| Mar | 3.46 | 2,750 | |
| Apr | 4.58 | 3,640 | |
| May | 4.40 | 3,497 | |
| Jun | 4.45 | 3,537 | |
| Jul | 4.34 | 3,449 | 1 |
| Aug | 2.87 | 2,281 | 185 |
| Sep | 2.87 | 2,281 | 185 |
| Oct | 3.20 | 2,543 | 143 |
| Nov | 3.03 | 2,408 | |
| Dec | 3.25 | 2,583 |
Apr is the wettest month (4.58 in, 3,640 gal off the roof); Feb the driest (2.54 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 Franklin?
Best fit: one 55-gallon barrel, which delivers about 425 gallons to the garden in a normal year (82.7% 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 Franklin's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 425 | 32,033 |
| 110 gal | 425 | 32,033 |
| 165 gal | 425 | 32,033 |
| 275 gal | 425 | 32,033 |
| 550 gal | 425 | 32,033 |
| 1,000 gal | 425 | 32,033 |
| 1,500 gal | 425 | 32,033 |
| 2,500 gal | 425 | 32,033 |
| 5,000 gal | 425 | 32,033 |
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