Northfield, MN rainwater: 28,176 gallons off a roof
Rainwater from a roof in Northfield, MN
28,176gallons a year
That is a 1,500 sq ft asphalt roof under Northfield, MN's normal 35.5 inches of rain, about 795 gallons for every inch that falls.
In Northfield, 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 Faribault station (11.2 mi away). Northfield, MN ranks 7th wettest of the 103 cities covered in Minnesota.
Month by month in Northfield
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.97 | 771 | |
| Feb | 1.00 | 795 | |
| Mar | 1.92 | 1,526 | |
| Apr | 3.13 | 2,488 | 152 |
| May | 4.37 | 3,473 | |
| Jun | 5.57 | 4,427 | |
| Jul | 4.64 | 3,688 | |
| Aug | 4.66 | 3,704 | |
| Sep | 3.68 | 2,925 | 84 |
| Oct | 2.60 | 2,066 | 218 |
| Nov | 1.67 | 1,327 | |
| Dec | 1.24 | 986 |
Jun is the wettest month (5.57 in, 4,427 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.
Barrel or cistern in Northfield?
Best fit: one 55-gallon barrel, which delivers about 369 gallons to the garden in a normal year (81.3% 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 Northfield's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 369 | 26,817 |
| 110 gal | 369 | 26,817 |
| 165 gal | 369 | 26,817 |
| 275 gal | 369 | 26,817 |
| 550 gal | 369 | 26,817 |
| 1,000 gal | 369 | 26,817 |
| 1,500 gal | 369 | 26,817 |
| 2,500 gal | 369 | 26,817 |
| 5,000 gal | 369 | 26,817 |
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