St. Peter, MN rainwater: 25,768 gallons off a roof
Rainwater from a roof in St. Peter, MN
25,768gallons a year
That is a 1,500 sq ft asphalt roof under St. Peter, MN's normal 32.4 inches of rain, about 795 gallons for every inch that falls.
In St. Peter, 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 St Peter station (0.5 mi away). St. Peter, MN ranks 63rd wettest of the 103 cities covered in Minnesota.
Month by month in St. Peter
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.96 | 763 | |
| Feb | 0.96 | 763 | |
| Mar | 1.79 | 1,423 | |
| Apr | 3.06 | 2,432 | 161 |
| May | 4.04 | 3,211 | 39 |
| Jun | 5.13 | 4,077 | |
| Jul | 4.41 | 3,505 | |
| Aug | 3.56 | 2,830 | 98 |
| Sep | 3.16 | 2,512 | 148 |
| Oct | 2.50 | 1,987 | 231 |
| Nov | 1.68 | 1,335 | |
| Dec | 1.17 | 930 |
Jun is the wettest month (5.13 in, 4,077 gal off the roof); Jan the driest (0.96 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 St. Peter?
Best fit: one 55-gallon barrel, which delivers about 555 gallons to the garden in a normal year (82.0% 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 St. Peter's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 555 | 24,297 |
| 110 gal | 555 | 24,297 |
| 165 gal | 555 | 24,297 |
| 275 gal | 555 | 24,297 |
| 550 gal | 555 | 24,297 |
| 1,000 gal | 555 | 24,297 |
| 1,500 gal | 555 | 24,297 |
| 2,500 gal | 555 | 24,297 |
| 5,000 gal | 555 | 24,297 |
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