Hamilton, OH rainwater: 32,921 gallons off a roof
Hamilton, OH: gallons off the roof each year
32,921gallons a year
That is a 1,500 sq ft asphalt roof under Hamilton, OH's normal 41.4 inches of rain, about 795 gallons for every inch that falls.
In Hamilton, 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 Hamilton Butler Co Rgnl Ap station (3.0 mi away). Hamilton, OH ranks 114th wettest of the 176 cities covered in Ohio.
Month by month in Hamilton
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.91 | 2,313 | |
| Feb | 2.41 | 1,915 | |
| Mar | 3.49 | 2,774 | |
| Apr | 4.63 | 3,680 | |
| May | 4.59 | 3,648 | |
| Jun | 4.06 | 3,227 | 36 |
| Jul | 3.67 | 2,917 | 85 |
| Aug | 2.95 | 2,345 | 175 |
| Sep | 3.04 | 2,416 | 163 |
| Oct | 3.17 | 2,520 | 147 |
| Nov | 3.16 | 2,512 | |
| Dec | 3.34 | 2,655 |
Apr is the wettest month (4.63 in, 3,680 gal off the roof); Feb the driest (2.41 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 Hamilton
Best fit: one 55-gallon barrel, which delivers about 491 gallons to the garden in a normal year (81.0% 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 Hamilton's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 491 | 31,230 |
| 110 gal | 491 | 31,230 |
| 165 gal | 491 | 31,230 |
| 275 gal | 491 | 31,230 |
| 550 gal | 491 | 31,230 |
| 1,000 gal | 491 | 31,230 |
| 1,500 gal | 491 | 31,230 |
| 2,500 gal | 491 | 31,230 |
| 5,000 gal | 491 | 31,230 |
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