Chanhassen, MN rainwater: 26,078 gallons off a roof

Chanhassen, MN: gallons off the roof each year

In Chanhassen, 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 Chanhassen Wsfo station (0.3 mi away). Chanhassen, MN ranks 56th wettest of the 103 cities covered in Minnesota.

Month by month in Chanhassen

Aug is the wettest month (4.76 in, 3,783 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.

Which tank size is worth it in Chanhassen

Best fit: one 55-gallon barrel, which delivers about 454 gallons to the garden in a normal year (82.4% 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 Chanhassen's roof water will pass straight through it.

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