Troy, OH rainwater: 32,380 gallons off a roof
Troy, OH: gallons off the roof each year
32,380gallons a year
That is a 1,500 sq ft asphalt roof under Troy, OH's normal 40.7 inches of rain, about 795 gallons for every inch that falls.
In Troy, 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 Piqua Wwtp station (6.3 mi away). Troy, OH ranks 134th wettest of the 176 cities covered in Ohio.
Month by month in Troy
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.97 | 2,361 | |
| Feb | 2.32 | 1,844 | |
| Mar | 3.18 | 2,527 | |
| Apr | 3.88 | 3,084 | 59 |
| May | 4.38 | 3,481 | |
| Jun | 4.18 | 3,322 | 21 |
| Jul | 4.19 | 3,330 | 20 |
| Aug | 3.58 | 2,845 | 96 |
| Sep | 2.98 | 2,369 | 171 |
| Oct | 2.86 | 2,273 | 186 |
| Nov | 3.23 | 2,567 | |
| Dec | 2.99 | 2,376 |
May is the wettest month (4.38 in, 3,481 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.
Which tank size is worth it in Troy
Best fit: one 55-gallon barrel, which delivers about 437 gallons to the garden in a normal year (79.1% 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 Troy's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 437 | 30,683 |
| 110 gal | 437 | 30,683 |
| 165 gal | 437 | 30,683 |
| 275 gal | 437 | 30,683 |
| 550 gal | 437 | 30,683 |
| 1,000 gal | 437 | 30,683 |
| 1,500 gal | 437 | 30,683 |
| 2,500 gal | 437 | 30,683 |
| 5,000 gal | 437 | 30,683 |
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