Owatonna, MN rainwater: 28,184 gallons off a roof
How much rain a roof in Owatonna, MN collects
28,184gallons a year
That is a 1,500 sq ft asphalt roof under Owatonna, MN's normal 35.5 inches of rain, about 795 gallons for every inch that falls.
In Owatonna, 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 Owatonna station (0.4 mi away). Owatonna, MN ranks 5th wettest of the 103 cities covered in Minnesota.
Month by month in Owatonna
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.87 | 691 | |
| Feb | 0.89 | 707 | |
| Mar | 1.99 | 1,582 | |
| Apr | 3.18 | 2,527 | 146 |
| May | 4.61 | 3,664 | |
| Jun | 5.28 | 4,197 | |
| Jul | 4.79 | 3,807 | |
| Aug | 4.84 | 3,847 | |
| Sep | 3.80 | 3,020 | 69 |
| Oct | 2.48 | 1,971 | 233 |
| Nov | 1.65 | 1,311 | |
| Dec | 1.08 | 858 |
Jun is the wettest month (5.28 in, 4,197 gal off the roof); Jan the driest (0.87 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 Owatonna?
Best fit: one 55-gallon barrel, which delivers about 365 gallons to the garden in a normal year (81.5% 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 Owatonna's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 365 | 26,829 |
| 110 gal | 365 | 26,829 |
| 165 gal | 365 | 26,829 |
| 275 gal | 365 | 26,829 |
| 550 gal | 365 | 26,829 |
| 1,000 gal | 365 | 26,829 |
| 1,500 gal | 365 | 26,829 |
| 2,500 gal | 365 | 26,829 |
| 5,000 gal | 365 | 26,829 |
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