Adrian, MI rainwater: 29,153 gallons off a roof

Rainwater from a roof in Adrian, MI

29,153gallons a year

That is a 1,500 sq ft asphalt roof under Adrian, MI's normal 36.7 inches of rain, about 795 gallons for every inch that falls.

In Adrian, MI 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 Adrian 2 Nne station (1.9 mi away). Adrian, MI ranks 20th wettest of the 90 cities covered in Michigan.

Month by month in Adrian

Month	Rain (in)	Off the roof (gal)	Garden shortfall (gal)
Jan	2.24	1,780
Feb	1.99	1,582
Mar	2.49	1,979
Apr	3.49	2,774	107
May	3.99	3,171	45
Jun	4.10	3,259	31
Jul	3.40	2,702	118
Aug	3.63	2,885	90
Sep	3.29	2,615	132
Oct	2.95	2,345	175
Nov	2.82	2,241
Dec	2.29	1,820

Jun is the wettest month (4.10 in, 3,259 gal off the roof); Feb the driest (1.99 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 Adrian?

Best fit: one 55-gallon barrel, which delivers about 549 gallons to the garden in a normal year (78.6% 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 Adrian's roof water will pass straight through it.

Tank	Water used (gal/yr)	Spills over (gal/yr)
55 gal	549	27,450
110 gal	549	27,450
165 gal	549	27,450
275 gal	549	27,450
550 gal	549	27,450
1,000 gal	549	27,450
1,500 gal	549	27,450
2,500 gal	549	27,450
5,000 gal	549	27,450

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 Michigan?

No rainwater harvesting regulations

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