Wilmington, OH rainwater: 35,528 gallons off a roof
Rainwater from a roof in Wilmington, OH
35,528gallons a year
That is a 1,500 sq ft asphalt roof under Wilmington, OH's normal 44.7 inches of rain, about 795 gallons for every inch that falls.
In Wilmington, 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 Wfo Wilmington station (0.6 mi away). Wilmington, OH ranks 15th wettest of the 176 cities covered in Ohio.
Month by month in Wilmington
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 3.25 | 2,583 | |
| Feb | 2.94 | 2,337 | |
| Mar | 4.05 | 3,219 | |
| Apr | 4.47 | 3,553 | |
| May | 4.81 | 3,823 | |
| Jun | 4.53 | 3,600 | |
| Jul | 4.13 | 3,283 | 27 |
| Aug | 3.42 | 2,718 | 116 |
| Sep | 3.03 | 2,408 | 165 |
| Oct | 3.36 | 2,671 | 123 |
| Nov | 3.28 | 2,607 | |
| Dec | 3.43 | 2,726 |
May is the wettest month (4.81 in, 3,823 gal off the roof); Feb the driest (2.94 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 Wilmington
Best fit: one 55-gallon barrel, which delivers about 351 gallons to the garden in a normal year (81.4% of its need).
Before you buy, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Wilmington's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 351 | 33,871 |
| 110 gal | 351 | 33,871 |
| 165 gal | 351 | 33,871 |
| 275 gal | 351 | 33,871 |
| 550 gal | 351 | 33,871 |
| 1,000 gal | 351 | 33,871 |
| 1,500 gal | 351 | 33,871 |
| 2,500 gal | 351 | 33,871 |
| 5,000 gal | 351 | 33,871 |
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