Richfield, MN rainwater: 27,484 gallons off a roof
How much rain a roof in Richfield, MN collects
27,484gallons a year
That is a 1,500 sq ft asphalt roof under Richfield, MN's normal 34.6 inches of rain, about 795 gallons for every inch that falls.
In Richfield, 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 Richfield 1.9 Wnw station (1.9 mi away). Richfield, MN ranks 11th wettest of the 103 cities covered in Minnesota.
Month by month in Richfield
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.89 | 707 | |
| Feb | 0.93 | 739 | |
| Mar | 1.78 | 1,415 | |
| Apr | 3.19 | 2,535 | 145 |
| May | 4.41 | 3,505 | |
| Jun | 4.68 | 3,720 | |
| Jul | 4.80 | 3,815 | |
| Aug | 4.68 | 3,720 | |
| Sep | 3.48 | 2,766 | 108 |
| Oct | 2.87 | 2,281 | 185 |
| Nov | 1.64 | 1,303 | |
| Dec | 1.23 | 978 |
Jul is the wettest month (4.80 in, 3,815 gal off the roof); Jan the driest (0.89 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 Richfield
Best fit: one 55-gallon barrel, which delivers about 361 gallons to the garden in a normal year (82.5% 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 Richfield's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 361 | 26,179 |
| 110 gal | 361 | 26,179 |
| 165 gal | 361 | 26,179 |
| 275 gal | 361 | 26,179 |
| 550 gal | 361 | 26,179 |
| 1,000 gal | 361 | 26,179 |
| 1,500 gal | 361 | 26,179 |
| 2,500 gal | 361 | 26,179 |
| 5,000 gal | 361 | 26,179 |
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