Winona, MN rainwater: 27,373 gallons off a roof
Winona, MN: gallons off the roof each year
27,373gallons a year
That is a 1,500 sq ft asphalt roof under Winona, MN's normal 34.4 inches of rain, about 795 gallons for every inch that falls.
In Winona, MN 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 Winona Dam 5 A station (2.5 mi away). Winona, MN ranks 12th wettest of the 103 cities covered in Minnesota.
Month by month in Winona
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 1.06 | 842 | |
| Feb | 1.02 | 811 | |
| Mar | 1.91 | 1,518 | |
| Apr | 3.65 | 2,901 | 87 |
| May | 4.14 | 3,290 | 26 |
| Jun | 4.83 | 3,839 | |
| Jul | 4.11 | 3,267 | 30 |
| Aug | 4.55 | 3,616 | |
| Sep | 3.57 | 2,837 | 97 |
| Oct | 2.53 | 2,011 | 227 |
| Nov | 1.85 | 1,470 | |
| Dec | 1.22 | 970 |
Jun is the wettest month (4.83 in, 3,839 gal off the roof); Feb the driest (1.02 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 Winona
Best fit: one 55-gallon barrel, which delivers about 369 gallons to the garden in a normal year (78.9% 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 Winona's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 369 | 25,954 |
| 110 gal | 369 | 25,954 |
| 165 gal | 369 | 25,954 |
| 275 gal | 369 | 25,954 |
| 550 gal | 369 | 25,954 |
| 1,000 gal | 369 | 25,954 |
| 1,500 gal | 369 | 25,954 |
| 2,500 gal | 369 | 25,954 |
| 5,000 gal | 369 | 25,954 |
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 Minnesota?
No statewide rainwater harvesting regulations; check county for local incentives
From the 2015 (Pacific Northwest National Laboratory report 24347); not yet re-checked against current law, so check with your state water agency before building anything large. Source