Delaware, OH rainwater: 33,080 gallons off a roof
Rainwater from a roof in Delaware, OH
33,080gallons a year
That is a 1,500 sq ft asphalt roof under Delaware, OH's normal 41.6 inches of rain, about 795 gallons for every inch that falls.
In Delaware, 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 Lewis Center 1.4 E station (7.9 mi away). Delaware, OH ranks 103rd wettest of the 176 cities covered in Ohio.
Month by month in Delaware
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.92 | 2,321 | |
| Feb | 2.32 | 1,844 | |
| Mar | 3.36 | 2,671 | |
| Apr | 3.97 | 3,155 | 47 |
| May | 4.65 | 3,696 | |
| Jun | 4.48 | 3,561 | |
| Jul | 4.19 | 3,330 | 20 |
| Aug | 3.52 | 2,798 | 103 |
| Sep | 2.87 | 2,281 | 185 |
| Oct | 3.09 | 2,456 | 157 |
| Nov | 2.96 | 2,353 | |
| Dec | 3.29 | 2,615 |
May is the wettest month (4.65 in, 3,696 gal off the roof); Feb the driest (2.32 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 Delaware?
Best fit: one 55-gallon barrel, which delivers about 408 gallons to the garden in a normal year (79.6% 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 Delaware's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 408 | 31,442 |
| 110 gal | 408 | 31,442 |
| 165 gal | 408 | 31,442 |
| 275 gal | 408 | 31,442 |
| 550 gal | 408 | 31,442 |
| 1,000 gal | 408 | 31,442 |
| 1,500 gal | 408 | 31,442 |
| 2,500 gal | 408 | 31,442 |
| 5,000 gal | 408 | 31,442 |
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