Greenville, OH rainwater: 31,999 gallons off a roof
Greenville, OH: gallons off the roof each year
31,999gallons a year
That is a 1,500 sq ft asphalt roof under Greenville, OH's normal 40.3 inches of rain, about 795 gallons for every inch that falls.
In Greenville, 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 Greenville Wtp station (1.5 mi away). Greenville, OH ranks 142nd wettest of the 176 cities covered in Ohio.
Month by month in Greenville
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.84 | 2,257 | |
| Feb | 2.23 | 1,772 | |
| Mar | 3.23 | 2,567 | |
| Apr | 4.18 | 3,322 | 21 |
| May | 4.31 | 3,426 | 5 |
| Jun | 4.42 | 3,513 | |
| Jul | 3.95 | 3,139 | 50 |
| Aug | 3.40 | 2,702 | 118 |
| Sep | 2.75 | 2,186 | 199 |
| Oct | 2.90 | 2,305 | 181 |
| Nov | 3.17 | 2,520 | |
| Dec | 2.88 | 2,289 |
Jun is the wettest month (4.42 in, 3,513 gal off the roof); Feb the driest (2.23 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 Greenville
Best fit: one 55-gallon barrel, which delivers about 471 gallons to the garden in a normal year (81.9% 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 Greenville's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 471 | 30,373 |
| 110 gal | 471 | 30,373 |
| 165 gal | 471 | 30,373 |
| 275 gal | 471 | 30,373 |
| 550 gal | 471 | 30,373 |
| 1,000 gal | 471 | 30,373 |
| 1,500 gal | 471 | 30,373 |
| 2,500 gal | 471 | 30,373 |
| 5,000 gal | 471 | 30,373 |
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