Duluth, MN rainwater: 24,703 gallons off a roof
Duluth, MN: gallons off the roof each year
24,703gallons a year
That is a 1,500 sq ft asphalt roof under Duluth, MN's normal 31.1 inches of rain, about 795 gallons for every inch that falls.
In Duluth, 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 Duluth 3.0 Ne station (4.4 mi away). Duluth, MN ranks 72nd wettest of the 103 cities covered in Minnesota.
Month by month in Duluth
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 1.02 | 811 | |
| Feb | 0.91 | 723 | |
| Mar | 1.49 | 1,184 | |
| Apr | 2.58 | 2,051 | 221 |
| May | 3.46 | 2,750 | 111 |
| Jun | 4.41 | 3,505 | |
| Jul | 4.11 | 3,267 | 30 |
| Aug | 3.42 | 2,718 | 116 |
| Sep | 3.46 | 2,750 | 111 |
| Oct | 3.03 | 2,408 | 165 |
| Nov | 1.71 | 1,359 | |
| Dec | 1.48 | 1,176 |
Jun is the wettest month (4.41 in, 3,505 gal off the roof); Feb the driest (0.91 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 Duluth
Best fit: one 55-gallon barrel, which delivers about 593 gallons to the garden in a normal year (78.7% 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 Duluth's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 593 | 23,134 |
| 110 gal | 593 | 23,134 |
| 165 gal | 593 | 23,134 |
| 275 gal | 593 | 23,134 |
| 550 gal | 593 | 23,134 |
| 1,000 gal | 593 | 23,134 |
| 1,500 gal | 593 | 23,134 |
| 2,500 gal | 593 | 23,134 |
| 5,000 gal | 593 | 23,134 |
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