Marion, OH rainwater: 31,339 gallons off a roof
How much rain a roof in Marion, OH collects
31,339gallons a year
That is a 1,500 sq ft asphalt roof under Marion, OH's normal 39.4 inches of rain, about 795 gallons for every inch that falls.
In Marion, 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 Marion 2 N station (1.5 mi away). Marion, OH ranks 146th wettest of the 176 cities covered in Ohio.
Month by month in Marion
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.73 | 2,170 | |
| Feb | 1.96 | 1,558 | |
| Mar | 2.71 | 2,154 | |
| Apr | 3.83 | 3,044 | 65 |
| May | 4.20 | 3,338 | 19 |
| Jun | 4.39 | 3,489 | |
| Jul | 4.26 | 3,386 | 11 |
| Aug | 3.30 | 2,623 | 131 |
| Sep | 3.33 | 2,647 | 127 |
| Oct | 3.00 | 2,384 | 168 |
| Nov | 3.01 | 2,392 | |
| Dec | 2.71 | 2,154 |
Jun is the wettest month (4.39 in, 3,489 gal off the roof); Feb the driest (1.96 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 Marion?
Best fit: one 55-gallon barrel, which delivers about 410 gallons to the garden in a normal year (78.7% 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 Marion's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 410 | 29,699 |
| 110 gal | 410 | 29,699 |
| 165 gal | 410 | 29,699 |
| 275 gal | 410 | 29,699 |
| 550 gal | 410 | 29,699 |
| 1,000 gal | 410 | 29,699 |
| 1,500 gal | 410 | 29,699 |
| 2,500 gal | 410 | 29,699 |
| 5,000 gal | 410 | 29,699 |
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