Moorhead, MN rainwater: 20,736 gallons off a roof
Moorhead, MN: gallons off the roof each year
20,736gallons a year
That is a 1,500 sq ft asphalt roof under Moorhead, MN's normal 26.1 inches of rain, about 795 gallons for every inch that falls.
In Moorhead, 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 Moorhead station (1.6 mi away). Moorhead, MN ranks 101st wettest of the 103 cities covered in Minnesota.
Month by month in Moorhead
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.73 | 580 | |
| Feb | 0.72 | 572 | |
| Mar | 1.33 | 1,057 | |
| Apr | 1.72 | 1,367 | 328 |
| May | 3.40 | 2,702 | 118 |
| Jun | 4.66 | 3,704 | |
| Jul | 3.37 | 2,678 | 122 |
| Aug | 2.74 | 2,178 | 201 |
| Sep | 2.94 | 2,337 | 176 |
| Oct | 2.51 | 1,995 | 229 |
| Nov | 1.05 | 835 | |
| Dec | 0.92 | 731 |
Jun is the wettest month (4.66 in, 3,704 gal off the roof); Feb the driest (0.72 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 Moorhead
Best fit: one 55-gallon barrel, which delivers about 932 gallons to the garden in a normal year (79.4% 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 Moorhead's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 932 | 19,025 |
| 110 gal | 985 | 18,971 |
| 165 gal | 985 | 18,971 |
| 275 gal | 985 | 18,971 |
| 550 gal | 985 | 18,971 |
| 1,000 gal | 985 | 18,971 |
| 1,500 gal | 985 | 18,971 |
| 2,500 gal | 985 | 18,971 |
| 5,000 gal | 985 | 18,971 |
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