Portsmouth, OH rainwater: 35,870 gallons off a roof
How much rain a roof in Portsmouth, OH collects
35,870gallons a year
That is a 1,500 sq ft asphalt roof under Portsmouth, OH's normal 45.1 inches of rain, about 795 gallons for every inch that falls.
In Portsmouth, 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 Rosemount 0.3 W station (2.8 mi away). Portsmouth, OH ranks 12th wettest of the 176 cities covered in Ohio.
Month by month in Portsmouth
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 3.31 | 2,631 | |
| Feb | 3.32 | 2,639 | |
| Mar | 4.35 | 3,457 | |
| Apr | 4.00 | 3,179 | 44 |
| May | 4.83 | 3,839 | |
| Jun | 4.24 | 3,370 | 14 |
| Jul | 4.90 | 3,895 | |
| Aug | 3.19 | 2,535 | 145 |
| Sep | 3.25 | 2,583 | 137 |
| Oct | 3.16 | 2,512 | 148 |
| Nov | 2.91 | 2,313 | |
| Dec | 3.67 | 2,917 |
Jul is the wettest month (4.90 in, 3,895 gal off the roof); Nov the driest (2.91 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 Portsmouth?
Best fit: one 55-gallon barrel, which delivers about 393 gallons to the garden in a normal year (80.6% 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 Portsmouth's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 393 | 34,232 |
| 110 gal | 393 | 34,232 |
| 165 gal | 393 | 34,232 |
| 275 gal | 393 | 34,232 |
| 550 gal | 393 | 34,232 |
| 1,000 gal | 393 | 34,232 |
| 1,500 gal | 393 | 34,232 |
| 2,500 gal | 393 | 34,232 |
| 5,000 gal | 393 | 34,232 |
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