Tiffin, OH rainwater: 30,751 gallons off a roof
Rainwater from a roof in Tiffin, OH
30,751gallons a year
That is a 1,500 sq ft asphalt roof under Tiffin, OH's normal 38.7 inches of rain, about 795 gallons for every inch that falls.
In Tiffin, 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 Tiffin station (0.7 mi away). Tiffin, OH ranks 149th wettest of the 176 cities covered in Ohio.
Month by month in Tiffin
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.57 | 2,043 | |
| Feb | 2.24 | 1,780 | |
| Mar | 2.73 | 2,170 | |
| Apr | 3.82 | 3,036 | 66 |
| May | 4.10 | 3,259 | 31 |
| Jun | 4.20 | 3,338 | 19 |
| Jul | 3.91 | 3,108 | 55 |
| Aug | 3.54 | 2,814 | 101 |
| Sep | 3.32 | 2,639 | 128 |
| Oct | 2.76 | 2,194 | 198 |
| Nov | 2.89 | 2,297 | |
| Dec | 2.61 | 2,074 |
Jun is the wettest month (4.20 in, 3,338 gal off the roof); Feb the driest (2.24 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 Tiffin?
Best fit: one 55-gallon barrel, which delivers about 472 gallons to the garden in a normal year (78.9% 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 Tiffin's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 472 | 29,124 |
| 110 gal | 472 | 29,124 |
| 165 gal | 472 | 29,124 |
| 275 gal | 472 | 29,124 |
| 550 gal | 472 | 29,124 |
| 1,000 gal | 472 | 29,124 |
| 1,500 gal | 472 | 29,124 |
| 2,500 gal | 472 | 29,124 |
| 5,000 gal | 472 | 29,124 |
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