Forest Lake, MN rainwater: 26,316 gallons off a roof
Forest Lake, MN: gallons off the roof each year
26,316gallons a year
That is a 1,500 sq ft asphalt roof under Forest Lake, MN's normal 33.1 inches of rain, about 795 gallons for every inch that falls.
In Forest Lake, 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 Forest Lake 5ne station (6.5 mi away). Forest Lake, MN ranks 42nd wettest of the 103 cities covered in Minnesota.
Month by month in Forest Lake
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.88 | 699 | |
| Feb | 0.90 | 715 | |
| Mar | 1.70 | 1,351 | |
| Apr | 3.00 | 2,384 | 168 |
| May | 4.36 | 3,465 | |
| Jun | 4.48 | 3,561 | |
| Jul | 4.70 | 3,736 | |
| Aug | 4.03 | 3,203 | 40 |
| Sep | 3.18 | 2,527 | 146 |
| Oct | 2.91 | 2,313 | 180 |
| Nov | 1.80 | 1,431 | |
| Dec | 1.17 | 930 |
Jul is the wettest month (4.70 in, 3,736 gal off the roof); Jan the driest (0.88 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
What size rain barrel for Forest Lake
Best fit: one 55-gallon barrel, which delivers about 423 gallons to the garden in a normal year (79.3% of its need).
If you set one up, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Forest Lake's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 423 | 24,903 |
| 110 gal | 423 | 24,903 |
| 165 gal | 423 | 24,903 |
| 275 gal | 423 | 24,903 |
| 550 gal | 423 | 24,903 |
| 1,000 gal | 423 | 24,903 |
| 1,500 gal | 423 | 24,903 |
| 2,500 gal | 423 | 24,903 |
| 5,000 gal | 423 | 24,903 |
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