Rochester, MN rainwater: 29,376 gallons off a roof
Rochester, MN: gallons off the roof each year
29,376gallons a year
That is a 1,500 sq ft asphalt roof under Rochester, MN's normal 37.0 inches of rain, about 795 gallons for every inch that falls.
In Rochester, 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 Rochester 2.6 Ne station (2.7 mi away). Rochester, MN ranks 1st wettest of the 103 cities covered in Minnesota.
Month by month in Rochester
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.97 | 771 | |
| Feb | 1.05 | 835 | |
| Mar | 2.05 | 1,629 | |
| Apr | 3.52 | 2,798 | 103 |
| May | 4.66 | 3,704 | |
| Jun | 5.35 | 4,252 | |
| Jul | 4.86 | 3,863 | |
| Aug | 4.84 | 3,847 | |
| Sep | 4.04 | 3,211 | 39 |
| Oct | 2.51 | 1,995 | 229 |
| Nov | 1.87 | 1,486 | |
| Dec | 1.24 | 986 |
Jun is the wettest month (5.35 in, 4,252 gal off the roof); Jan the driest (0.97 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
What size rain barrel for Rochester
Best fit: one 55-gallon barrel, which delivers about 306 gallons to the garden in a normal year (82.4% of its need).
Before you buy, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Rochester's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 306 | 28,125 |
| 110 gal | 306 | 28,125 |
| 165 gal | 306 | 28,125 |
| 275 gal | 306 | 28,125 |
| 550 gal | 306 | 28,125 |
| 1,000 gal | 306 | 28,125 |
| 1,500 gal | 306 | 28,125 |
| 2,500 gal | 306 | 28,125 |
| 5,000 gal | 306 | 28,125 |
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