Bloomington, MN rainwater: 27,039 gallons off a roof
Rainwater from a roof in Bloomington, MN
27,039gallons a year
That is a 1,500 sq ft asphalt roof under Bloomington, MN's normal 34.0 inches of rain, about 795 gallons for every inch that falls.
In Bloomington, 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 Edina 1.9 Sse station (2.9 mi away). Bloomington, MN ranks 18th wettest of the 103 cities covered in Minnesota.
Month by month in Bloomington
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.81 | 644 | |
| Feb | 0.77 | 612 | |
| Mar | 1.75 | 1,391 | |
| Apr | 3.06 | 2,432 | 161 |
| May | 4.46 | 3,545 | |
| Jun | 4.68 | 3,720 | |
| Jul | 4.89 | 3,887 | |
| Aug | 4.65 | 3,696 | |
| Sep | 3.44 | 2,734 | 113 |
| Oct | 2.77 | 2,202 | 197 |
| Nov | 1.57 | 1,248 | |
| Dec | 1.17 | 930 |
Jul is the wettest month (4.89 in, 3,887 gal off the roof); Feb the driest (0.77 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 Bloomington?
Best fit: one 55-gallon barrel, which delivers about 388 gallons to the garden in a normal year (82.3% 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 Bloomington's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 388 | 25,706 |
| 110 gal | 388 | 25,706 |
| 165 gal | 388 | 25,706 |
| 275 gal | 388 | 25,706 |
| 550 gal | 388 | 25,706 |
| 1,000 gal | 388 | 25,706 |
| 1,500 gal | 388 | 25,706 |
| 2,500 gal | 388 | 25,706 |
| 5,000 gal | 388 | 25,706 |
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