Plymouth, MN rainwater: 27,564 gallons off a roof
How much rain a roof in Plymouth, MN collects
27,564gallons a year
That is a 1,500 sq ft asphalt roof under Plymouth, MN's normal 34.7 inches of rain, about 795 gallons for every inch that falls.
In Plymouth, 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 New Hope station (4.2 mi away). Plymouth, MN ranks 9th wettest of the 103 cities covered in Minnesota.
Month by month in Plymouth
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.95 | 755 | |
| Feb | 1.02 | 811 | |
| Mar | 1.88 | 1,494 | |
| Apr | 3.31 | 2,631 | 130 |
| May | 4.49 | 3,569 | |
| Jun | 4.64 | 3,688 | |
| Jul | 4.51 | 3,585 | |
| Aug | 4.18 | 3,322 | 21 |
| Sep | 3.45 | 2,742 | 112 |
| Oct | 2.98 | 2,369 | 171 |
| Nov | 1.87 | 1,486 | |
| Dec | 1.40 | 1,113 |
Jun is the wettest month (4.64 in, 3,688 gal off the roof); Jan the driest (0.95 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 Plymouth?
Best fit: one 55-gallon barrel, which delivers about 344 gallons to the garden in a normal year (79.3% 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 Plymouth's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 344 | 26,215 |
| 110 gal | 344 | 26,215 |
| 165 gal | 344 | 26,215 |
| 275 gal | 344 | 26,215 |
| 550 gal | 344 | 26,215 |
| 1,000 gal | 344 | 26,215 |
| 1,500 gal | 344 | 26,215 |
| 2,500 gal | 344 | 26,215 |
| 5,000 gal | 344 | 26,215 |
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