Westerville, OH rainwater: 33,565 gallons off a roof
Rainwater from a roof in Westerville, OH
33,565gallons a year
That is a 1,500 sq ft asphalt roof under Westerville, OH's normal 42.2 inches of rain, about 795 gallons for every inch that falls.
In Westerville, 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 Westerville station (1.6 mi away). Westerville, OH ranks 79th wettest of the 176 cities covered in Ohio.
Month by month in Westerville
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.93 | 2,329 | |
| Feb | 2.36 | 1,876 | |
| Mar | 3.42 | 2,718 | |
| Apr | 3.91 | 3,108 | 55 |
| May | 4.22 | 3,354 | 16 |
| Jun | 5.02 | 3,990 | |
| Jul | 4.56 | 3,624 | |
| Aug | 3.64 | 2,893 | 89 |
| Sep | 3.29 | 2,615 | 132 |
| Oct | 2.95 | 2,345 | 175 |
| Nov | 2.88 | 2,289 | |
| Dec | 3.05 | 2,424 |
Jun is the wettest month (5.02 in, 3,990 gal off the roof); Feb the driest (2.36 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 Westerville
Best fit: one 55-gallon barrel, which delivers about 361 gallons to the garden in a normal year (77.4% 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 Westerville's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 361 | 31,899 |
| 110 gal | 361 | 31,899 |
| 165 gal | 361 | 31,899 |
| 275 gal | 361 | 31,899 |
| 550 gal | 361 | 31,899 |
| 1,000 gal | 361 | 31,899 |
| 1,500 gal | 361 | 31,899 |
| 2,500 gal | 361 | 31,899 |
| 5,000 gal | 361 | 31,899 |
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